https://source.android.com/ 
/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.app;

import android.animation.Animator;
import android.annotation.CallSuper;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.StringRes;
import android.content.ComponentCallbacks2;
import android.content.Context;
import android.content.Intent;
import android.content.IntentSender;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.os.Build;
import android.os.Build.VERSION_CODES;
import android.os.Bundle;
import android.os.Looper;
import android.os.Parcel;
import android.os.Parcelable;
import android.os.UserHandle;
import android.transition.Transition;
import android.transition.TransitionInflater;
import android.transition.TransitionSet;
import android.util.AndroidRuntimeException;
import android.util.ArrayMap;
import android.util.AttributeSet;
import android.util.DebugUtils;
import android.util.SparseArray;
import android.util.SuperNotCalledException;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnCreateContextMenuListener;
import android.view.ViewGroup;
import android.widget.AdapterView;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.lang.reflect.InvocationTargetException;


A Fragment is a piece of an application's user interface or behavior that can be placed in an Activity. Interaction with fragments is done through FragmentManager, which can be obtained via Activity.getFragmentManager() and Fragment.getFragmentManager(). 
The Fragment class can be used many ways to achieve a wide variety of results. In its core, it represents a particular operation or interface that is running within a larger Activity. A Fragment is closely tied to the Activity it is in, and can not be used apart from one. Though Fragment defines its own lifecycle, that lifecycle is dependent on its activity: if the activity is stopped, no fragments inside of it can be started; when the activity is destroyed, all fragments will be destroyed. 
All subclasses of Fragment must include a public no-argument constructor.
The framework will often re-instantiate a fragment class when needed,
in particular during state restore, and needs to be able to find this
constructor to instantiate it.  If the no-argument constructor is not
available, a runtime exception will occur in some cases during state
restore.

Topics covered here:

    

  1. Older Platforms

  2. Lifecycle

  3. Layout

  4. Back Stack





Developer Guides


For more information about using fragments, read the
Fragments developer guide.





Older Platforms
 While the Fragment API was introduced in VERSION_CODES.HONEYCOMB, a version of the API at is also available for use on older platforms through FragmentActivity. See the blog post 
Fragments For All for more details.


Lifecycle


Though a Fragment's lifecycle is tied to its owning activity, it has its own wrinkle on the standard activity lifecycle. It includes basic activity lifecycle methods such as onResume, but also important are methods related to interactions with the activity and UI generation. 
The core series of lifecycle methods that are called to bring a fragment
up to resumed state (interacting with the user) are:

    

  1.  onAttach called once the fragment is associated with its activity. 
  2.  onCreate called to do initial creation of the fragment. 
  3.  onCreateView creates and returns the view hierarchy associated with the fragment. 
  4.  onActivityCreated tells the fragment that its activity has completed its own Activity.onCreate(). 
  5.  onViewStateRestored tells the fragment that all of the saved state of its view hierarchy has been restored. 
  6.  onStart makes the fragment visible to the user (based on its containing activity being started). 
  7.  onResume makes the fragment begin interacting with the user (based on its containing activity being resumed). 


As a fragment is no longer being used, it goes through a reverse
series of callbacks:

    

  1.  onPause fragment is no longer interacting with the user either because its activity is being paused or a fragment operation is modifying it in the activity. 
  2.  onStop fragment is no longer visible to the user either because its activity is being stopped or a fragment operation is modifying it in the activity. 
  3.  onDestroyView allows the fragment to clean up resources associated with its View. 
  4.  onDestroy called to do final cleanup of the fragment's state. 
  5.  onDetach called immediately prior to the fragment no longer being associated with its activity. 



Layout


Fragments can be used as part of your application's layout, allowing
you to better modularize your code and more easily adjust your user
interface to the screen it is running on.  As an example, we can look
at a simple program consisting of a list of items, and display of the
details of each item.


An activity's layout XML can include <fragment> tags
to embed fragment instances inside of the layout.  For example, here is
a simple layout that embeds one fragment:

{@sample development/samples/ApiDemos/res/layout/fragment_layout.xml layout}

The layout is installed in the activity in the normal way:

{@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
     main}

The titles fragment, showing a list of titles, is fairly simple, relying on ListFragment for most of its work. Note the implementation of clicking an item: depending on the current activity's layout, it can either create and display a new fragment to show the details in-place (more about this later), or start a new activity to show the details.

{@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
     titles}

The details fragment showing the contents of a selected item just
displays a string of text based on an index of a string array built in to
the app:

{@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
     details}

In this case when the user clicks on a title, there is no details
container in the current activity, so the titles fragment's click code will
launch a new activity to display the details fragment:

{@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
     details_activity}

However the screen may be large enough to show both the list of titles
and details about the currently selected title.  To use such a layout on
a landscape screen, this alternative layout can be placed under layout-land:

{@sample development/samples/ApiDemos/res/layout-land/fragment_layout.xml layout}

Note how the prior code will adjust to this alternative UI flow: the titles
fragment will now embed the details fragment inside of this activity, and the
details activity will finish itself if it is running in a configuration
where the details can be shown in-place.

When a configuration change causes the activity hosting these fragments to restart, its new instance may use a different layout that doesn't include the same fragments as the previous layout. In this case all of the previous fragments will still be instantiated and running in the new instance. However, any that are no longer associated with a <fragment> tag in the view hierarchy will not have their content view created and will return false from isInLayout. (The code here also shows how you can determine if a fragment placed in a container is no longer running in a layout with that container and avoid creating its view hierarchy in that case.) 
The attributes of the <fragment> tag are used to control the LayoutParams provided when attaching the fragment's view to the parent container. They can also be parsed by the fragment in onInflate as parameters. 
The fragment being instantiated must have some kind of unique identifier
so that it can be re-associated with a previous instance if the parent
activity needs to be destroyed and recreated.  This can be provided these
ways:

    

  • If nothing is explicitly supplied, the view ID of the container will
be used.

  • android:tag can be used in <fragment> to provide
a specific tag name for the fragment.

  • android:id can be used in <fragment> to provide
a specific identifier for the fragment.




Back Stack


The transaction in which fragments are modified can be placed on an
internal back-stack of the owning activity.  When the user presses back
in the activity, any transactions on the back stack are popped off before
the activity itself is finished.

For example, consider this simple fragment that is instantiated with
an integer argument and displays that in a TextView in its UI:

{@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentStack.java
     fragment}

A function that creates a new instance of the fragment, replacing
whatever current fragment instance is being shown and pushing that change
on to the back stack could be written as:
{@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentStack.java
     add_stack}

After each call to this function, a new entry is on the stack, and
pressing back will pop it to return the user to whatever previous state
the activity UI was in.

Deprecated:Use the Support Library Fragment for consistent behavior across all devices and access to Lifecycle.
/**
 * A Fragment is a piece of an application's user interface or behavior
 * that can be placed in an {@link Activity}.  Interaction with fragments
 * is done through {@link FragmentManager}, which can be obtained via
 * {@link Activity#getFragmentManager() Activity.getFragmentManager()} and
 * {@link Fragment#getFragmentManager() Fragment.getFragmentManager()}.
 *
 * <p>The Fragment class can be used many ways to achieve a wide variety of
 * results. In its core, it represents a particular operation or interface
 * that is running within a larger {@link Activity}.  A Fragment is closely
 * tied to the Activity it is in, and can not be used apart from one.  Though
 * Fragment defines its own lifecycle, that lifecycle is dependent on its
 * activity: if the activity is stopped, no fragments inside of it can be
 * started; when the activity is destroyed, all fragments will be destroyed.
 *
 * <p>All subclasses of Fragment must include a public no-argument constructor.
 * The framework will often re-instantiate a fragment class when needed,
 * in particular during state restore, and needs to be able to find this
 * constructor to instantiate it.  If the no-argument constructor is not
 * available, a runtime exception will occur in some cases during state
 * restore.
 *
 * <p>Topics covered here:
 * <ol>
 * <li><a href="#OlderPlatforms">Older Platforms</a>
 * <li><a href="#Lifecycle">Lifecycle</a>
 * <li><a href="#Layout">Layout</a>
 * <li><a href="#BackStack">Back Stack</a>
 * </ol>
 *
 * <div class="special reference">
 * <h3>Developer Guides</h3>
 * <p>For more information about using fragments, read the
 * <a href="{@docRoot}guide/components/fragments.html">Fragments</a> developer guide.</p>
 * </div>
 *
 * <a name="OlderPlatforms"></a>
 * <h3>Older Platforms</h3>
 *
 * While the Fragment API was introduced in
 * {@link android.os.Build.VERSION_CODES#HONEYCOMB}, a version of the API
 * at is also available for use on older platforms through
 * {@link android.support.v4.app.FragmentActivity}.  See the blog post
 * <a href="http://android-developers.blogspot.com/2011/03/fragments-for-all.html">
 * Fragments For All</a> for more details.
 *
 * <a name="Lifecycle"></a>
 * <h3>Lifecycle</h3>
 *
 * <p>Though a Fragment's lifecycle is tied to its owning activity, it has
 * its own wrinkle on the standard activity lifecycle.  It includes basic
 * activity lifecycle methods such as {@link #onResume}, but also important
 * are methods related to interactions with the activity and UI generation.
 *
 * <p>The core series of lifecycle methods that are called to bring a fragment
 * up to resumed state (interacting with the user) are:
 *
 * <ol>
 * <li> {@link #onAttach} called once the fragment is associated with its activity.
 * <li> {@link #onCreate} called to do initial creation of the fragment.
 * <li> {@link #onCreateView} creates and returns the view hierarchy associated
 * with the fragment.
 * <li> {@link #onActivityCreated} tells the fragment that its activity has
 * completed its own {@link Activity#onCreate Activity.onCreate()}.
 * <li> {@link #onViewStateRestored} tells the fragment that all of the saved
 * state of its view hierarchy has been restored.
 * <li> {@link #onStart} makes the fragment visible to the user (based on its
 * containing activity being started).
 * <li> {@link #onResume} makes the fragment begin interacting with the user
 * (based on its containing activity being resumed).
 * </ol>
 *
 * <p>As a fragment is no longer being used, it goes through a reverse
 * series of callbacks:
 *
 * <ol>
 * <li> {@link #onPause} fragment is no longer interacting with the user either
 * because its activity is being paused or a fragment operation is modifying it
 * in the activity.
 * <li> {@link #onStop} fragment is no longer visible to the user either
 * because its activity is being stopped or a fragment operation is modifying it
 * in the activity.
 * <li> {@link #onDestroyView} allows the fragment to clean up resources
 * associated with its View.
 * <li> {@link #onDestroy} called to do final cleanup of the fragment's state.
 * <li> {@link #onDetach} called immediately prior to the fragment no longer
 * being associated with its activity.
 * </ol>
 *
 * <a name="Layout"></a>
 * <h3>Layout</h3>
 *
 * <p>Fragments can be used as part of your application's layout, allowing
 * you to better modularize your code and more easily adjust your user
 * interface to the screen it is running on.  As an example, we can look
 * at a simple program consisting of a list of items, and display of the
 * details of each item.</p>
 *
 * <p>An activity's layout XML can include <code>&lt;fragment&gt;</code> tags
 * to embed fragment instances inside of the layout.  For example, here is
 * a simple layout that embeds one fragment:</p>
 *
 * {@sample development/samples/ApiDemos/res/layout/fragment_layout.xml layout}
 *
 * <p>The layout is installed in the activity in the normal way:</p>
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
 *      main}
 *
 * <p>The titles fragment, showing a list of titles, is fairly simple, relying
 * on {@link ListFragment} for most of its work.  Note the implementation of
 * clicking an item: depending on the current activity's layout, it can either
 * create and display a new fragment to show the details in-place (more about
 * this later), or start a new activity to show the details.</p>
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
 *      titles}
 *
 * <p>The details fragment showing the contents of a selected item just
 * displays a string of text based on an index of a string array built in to
 * the app:</p>
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
 *      details}
 *
 * <p>In this case when the user clicks on a title, there is no details
 * container in the current activity, so the titles fragment's click code will
 * launch a new activity to display the details fragment:</p>
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
 *      details_activity}
 *
 * <p>However the screen may be large enough to show both the list of titles
 * and details about the currently selected title.  To use such a layout on
 * a landscape screen, this alternative layout can be placed under layout-land:</p>
 *
 * {@sample development/samples/ApiDemos/res/layout-land/fragment_layout.xml layout}
 *
 * <p>Note how the prior code will adjust to this alternative UI flow: the titles
 * fragment will now embed the details fragment inside of this activity, and the
 * details activity will finish itself if it is running in a configuration
 * where the details can be shown in-place.
 *
 * <p>When a configuration change causes the activity hosting these fragments
 * to restart, its new instance may use a different layout that doesn't
 * include the same fragments as the previous layout.  In this case all of
 * the previous fragments will still be instantiated and running in the new
 * instance.  However, any that are no longer associated with a &lt;fragment&gt;
 * tag in the view hierarchy will not have their content view created
 * and will return false from {@link #isInLayout}.  (The code here also shows
 * how you can determine if a fragment placed in a container is no longer
 * running in a layout with that container and avoid creating its view hierarchy
 * in that case.)
 *
 * <p>The attributes of the &lt;fragment&gt; tag are used to control the
 * LayoutParams provided when attaching the fragment's view to the parent
 * container.  They can also be parsed by the fragment in {@link #onInflate}
 * as parameters.
 *
 * <p>The fragment being instantiated must have some kind of unique identifier
 * so that it can be re-associated with a previous instance if the parent
 * activity needs to be destroyed and recreated.  This can be provided these
 * ways:
 *
 * <ul>
 * <li>If nothing is explicitly supplied, the view ID of the container will
 * be used.
 * <li><code>android:tag</code> can be used in &lt;fragment&gt; to provide
 * a specific tag name for the fragment.
 * <li><code>android:id</code> can be used in &lt;fragment&gt; to provide
 * a specific identifier for the fragment.
 * </ul>
 *
 * <a name="BackStack"></a>
 * <h3>Back Stack</h3>
 *
 * <p>The transaction in which fragments are modified can be placed on an
 * internal back-stack of the owning activity.  When the user presses back
 * in the activity, any transactions on the back stack are popped off before
 * the activity itself is finished.
 *
 * <p>For example, consider this simple fragment that is instantiated with
 * an integer argument and displays that in a TextView in its UI:</p>
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentStack.java
 *      fragment}
 *
 * <p>A function that creates a new instance of the fragment, replacing
 * whatever current fragment instance is being shown and pushing that change
 * on to the back stack could be written as:
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentStack.java
 *      add_stack}
 *
 * <p>After each call to this function, a new entry is on the stack, and
 * pressing back will pop it to return the user to whatever previous state
 * the activity UI was in.
 *
 * @deprecated Use the <a href="{@docRoot}tools/extras/support-library.html">Support Library</a>
 *      {@link android.support.v4.app.Fragment} for consistent behavior across all devices
 *      and access to <a href="{@docRoot}topic/libraries/architecture/lifecycle.html">Lifecycle</a>.
 */
@Deprecated
public class Fragment implements ComponentCallbacks2, OnCreateContextMenuListener {
    private static final ArrayMap<String, Class<?>> sClassMap =
            new ArrayMap<String, Class<?>>();

    static final int INVALID_STATE = -1;   // Invalid state used as a null value.
    static final int INITIALIZING = 0;     // Not yet created.
    static final int CREATED = 1;          // Created.
    static final int ACTIVITY_CREATED = 2; // The activity has finished its creation.
    static final int STOPPED = 3;          // Fully created, not started.
    static final int STARTED = 4;          // Created and started, not resumed.
    static final int RESUMED = 5;          // Created started and resumed.

    private static final Transition USE_DEFAULT_TRANSITION = new TransitionSet();

    int mState = INITIALIZING;

    // When instantiated from saved state, this is the saved state.
    Bundle mSavedFragmentState;
    SparseArray<Parcelable> mSavedViewState;

    // Index into active fragment array.
    int mIndex = -1;

    // Internal unique name for this fragment;
    String mWho;

    // Construction arguments;
    Bundle mArguments;

    // Target fragment.
    Fragment mTarget;

    // For use when retaining a fragment: this is the index of the last mTarget.
    int mTargetIndex = -1;

    // Target request code.
    int mTargetRequestCode;

    // True if the fragment is in the list of added fragments.
    boolean mAdded;

    // If set this fragment is being removed from its activity.
    boolean mRemoving;

    // Set to true if this fragment was instantiated from a layout file.
    boolean mFromLayout;

    // Set to true when the view has actually been inflated in its layout.
    boolean mInLayout;

    // True if this fragment has been restored from previously saved state.
    boolean mRestored;

    // True if performCreateView has been called and a matching call to performDestroyView
    // has not yet happened.
    boolean mPerformedCreateView;

    // Number of active back stack entries this fragment is in.
    int mBackStackNesting;

    // The fragment manager we are associated with.  Set as soon as the
    // fragment is used in a transaction; cleared after it has been removed
    // from all transactions.
    FragmentManagerImpl mFragmentManager;

    // Activity this fragment is attached to.
    FragmentHostCallback mHost;

    // Private fragment manager for child fragments inside of this one.
    FragmentManagerImpl mChildFragmentManager;

    // For use when restoring fragment state and descendant fragments are retained.
    // This state is set by FragmentState.instantiate and cleared in onCreate.
    FragmentManagerNonConfig mChildNonConfig;

    // If this Fragment is contained in another Fragment, this is that container.
    Fragment mParentFragment;

    // The optional identifier for this fragment -- either the container ID if it
    // was dynamically added to the view hierarchy, or the ID supplied in
    // layout.
    int mFragmentId;

    // When a fragment is being dynamically added to the view hierarchy, this
    // is the identifier of the parent container it is being added to.
    int mContainerId;

    // The optional named tag for this fragment -- usually used to find
    // fragments that are not part of the layout.
    String mTag;

    // Set to true when the app has requested that this fragment be hidden
    // from the user.
    boolean mHidden;

    // Set to true when the app has requested that this fragment be detached.
    boolean mDetached;

    // If set this fragment would like its instance retained across
    // configuration changes.
    boolean mRetainInstance;

    // If set this fragment is being retained across the current config change.
    boolean mRetaining;

    // If set this fragment has menu items to contribute.
    boolean mHasMenu;

    // Set to true to allow the fragment's menu to be shown.
    boolean mMenuVisible = true;

    // Used to verify that subclasses call through to super class.
    boolean mCalled;

    // The parent container of the fragment after dynamically added to UI.
    ViewGroup mContainer;

    // The View generated for this fragment.
    View mView;

    // Whether this fragment should defer starting until after other fragments
    // have been started and their loaders are finished.
    boolean mDeferStart;

    // Hint provided by the app that this fragment is currently visible to the user.
    boolean mUserVisibleHint = true;

    LoaderManagerImpl mLoaderManager;
    boolean mLoadersStarted;
    boolean mCheckedForLoaderManager;

    // The animation and transition information for the fragment. This will be null
    // unless the elements are explicitly accessed and should remain null for Fragments
    // without Views.
    AnimationInfo mAnimationInfo;

    // True if the View was added, and its animation has yet to be run. This could
    // also indicate that the fragment view hasn't been made visible, even if there is no
    // animation for this fragment.
    boolean mIsNewlyAdded;

    // True if mHidden has been changed and the animation should be scheduled.
    boolean mHiddenChanged;

    // The cached value from onGetLayoutInflater(Bundle) that will be returned from
    // getLayoutInflater()
    LayoutInflater mLayoutInflater;

    // Keep track of whether or not this Fragment has run performCreate(). Retained instance
    // fragments can have mRetaining set to true without going through creation, so we must
    // track it separately.
    boolean mIsCreated;

    
State information that has been retrieved from a fragment instance through 
FragmentManager.saveFragmentInstanceState. 
Deprecated:Use SavedState
/**
     * State information that has been retrieved from a fragment instance
     * through {@link FragmentManager#saveFragmentInstanceState(Fragment)
     * FragmentManager.saveFragmentInstanceState}.
     *
     * @deprecated Use {@link android.support.v4.app.Fragment.SavedState}
     */
    @Deprecated
    public static class SavedState implements Parcelable {
        final Bundle mState;

        SavedState(Bundle state) {
            mState = state;
        }

        SavedState(Parcel in, ClassLoader loader) {
            mState = in.readBundle();
            if (loader != null && mState != null) {
                mState.setClassLoader(loader);
            }
        }

        @Override
        public int describeContents() {
            return 0;
        }

        @Override
        public void writeToParcel(Parcel dest, int flags) {
            dest.writeBundle(mState);
        }

        public static final Parcelable.ClassLoaderCreator<SavedState> CREATOR
                = new Parcelable.ClassLoaderCreator<SavedState>() {
            public SavedState createFromParcel(Parcel in) {
                return new SavedState(in, null);
            }

            public SavedState createFromParcel(Parcel in, ClassLoader loader) {
                return new SavedState(in, loader);
            }

            public SavedState[] newArray(int size) {
                return new SavedState[size];
            }
        };
    }

    
Thrown by Fragment.instantiate(Context, String, Bundle) when there is an instantiation failure. 
Deprecated:Use InstantiationException
/**
     * Thrown by {@link Fragment#instantiate(Context, String, Bundle)} when
     * there is an instantiation failure.
     *
     * @deprecated Use {@link android.support.v4.app.Fragment.InstantiationException}
     */
    @Deprecated
    static public class InstantiationException extends AndroidRuntimeException {
        public InstantiationException(String msg, Exception cause) {
            super(msg, cause);
        }
    }

    
Default constructor.  Every fragment must have an empty constructor, so it can be instantiated when restoring its activity's state. It is strongly recommended that subclasses do not have other constructors with parameters, since these constructors will not be called when the fragment is re-instantiated; instead, arguments can be supplied by the caller with setArguments and later retrieved by the Fragment with getArguments. 
Applications should generally not implement a constructor. Prefer onAttach(Context) instead. It is the first place application code can run where the fragment is ready to be used - the point where the fragment is actually associated with its context. Some applications may also want to implement onInflate to retrieve attributes from a layout resource, although note this happens when the fragment is attached. 
/**
     * Default constructor.  <strong>Every</strong> fragment must have an
     * empty constructor, so it can be instantiated when restoring its
     * activity's state.  It is strongly recommended that subclasses do not
     * have other constructors with parameters, since these constructors
     * will not be called when the fragment is re-instantiated; instead,
     * arguments can be supplied by the caller with {@link #setArguments}
     * and later retrieved by the Fragment with {@link #getArguments}.
     *
     * <p>Applications should generally not implement a constructor. Prefer
     * {@link #onAttach(Context)} instead. It is the first place application code can run where
     * the fragment is ready to be used - the point where the fragment is actually associated with
     * its context. Some applications may also want to implement {@link #onInflate} to retrieve
     * attributes from a layout resource, although note this happens when the fragment is attached.
     */
    public Fragment() {
    }

    
Like instantiate(Context, String, Bundle) but with a null argument Bundle. 
/**
     * Like {@link #instantiate(Context, String, Bundle)} but with a null
     * argument Bundle.
     */
    public static Fragment instantiate(Context context, String fname) {
        return instantiate(context, fname, null);
    }

    
Create a new instance of a Fragment with the given class name.  This is
the same as calling its empty constructor.

Params:
  • context – The calling context being used to instantiate the fragment.
This is currently just used to get its ClassLoader.
  • fname – The class name of the fragment to instantiate.
  • args – Bundle of arguments to supply to the fragment, which it can retrieve with getArguments(). May be null.
Throws:
  • InstantiationException – If there is a failure in instantiating
the given fragment class.  This is a runtime exception; it is not
normally expected to happen.
Returns:Returns a new fragment instance.
/**
     * Create a new instance of a Fragment with the given class name.  This is
     * the same as calling its empty constructor.
     *
     * @param context The calling context being used to instantiate the fragment.
     * This is currently just used to get its ClassLoader.
     * @param fname The class name of the fragment to instantiate.
     * @param args Bundle of arguments to supply to the fragment, which it
     * can retrieve with {@link #getArguments()}.  May be null.
     * @return Returns a new fragment instance.
     * @throws InstantiationException If there is a failure in instantiating
     * the given fragment class.  This is a runtime exception; it is not
     * normally expected to happen.
     */
    public static Fragment instantiate(Context context, String fname, @Nullable Bundle args) {
        try {
            Class<?> clazz = sClassMap.get(fname);
            if (clazz == null) {
                // Class not found in the cache, see if it's real, and try to add it
                clazz = context.getClassLoader().loadClass(fname);
                if (!Fragment.class.isAssignableFrom(clazz)) {
                    throw new InstantiationException("Trying to instantiate a class " + fname
                            + " that is not a Fragment", new ClassCastException());
                }
                sClassMap.put(fname, clazz);
            }
            Fragment f = (Fragment) clazz.getConstructor().newInstance();
            if (args != null) {
                args.setClassLoader(f.getClass().getClassLoader());
                f.setArguments(args);
            }
            return f;
        } catch (ClassNotFoundException e) {
            throw new InstantiationException("Unable to instantiate fragment " + fname
                    + ": make sure class name exists, is public, and has an"
                    + " empty constructor that is public", e);
        } catch (java.lang.InstantiationException e) {
            throw new InstantiationException("Unable to instantiate fragment " + fname
                    + ": make sure class name exists, is public, and has an"
                    + " empty constructor that is public", e);
        } catch (IllegalAccessException e) {
            throw new InstantiationException("Unable to instantiate fragment " + fname
                    + ": make sure class name exists, is public, and has an"
                    + " empty constructor that is public", e);
        } catch (NoSuchMethodException e) {
            throw new InstantiationException("Unable to instantiate fragment " + fname
                    + ": could not find Fragment constructor", e);
        } catch (InvocationTargetException e) {
            throw new InstantiationException("Unable to instantiate fragment " + fname
                    + ": calling Fragment constructor caused an exception", e);
        }
    }

    final void restoreViewState(Bundle savedInstanceState) {
        if (mSavedViewState != null) {
            mView.restoreHierarchyState(mSavedViewState);
            mSavedViewState = null;
        }
        mCalled = false;
        onViewStateRestored(savedInstanceState);
        if (!mCalled) {
            throw new SuperNotCalledException("Fragment " + this
                    + " did not call through to super.onViewStateRestored()");
        }
    }

    final void setIndex(int index, Fragment parent) {
        mIndex = index;
        if (parent != null) {
            mWho = parent.mWho + ":" + mIndex;
        } else {
            mWho = "android:fragment:" + mIndex;
        }
    }

    final boolean isInBackStack() {
        return mBackStackNesting > 0;
    }

    
Subclasses can not override equals().

/**
     * Subclasses can not override equals().
     */
    @Override final public boolean equals(Object o) {
        return super.equals(o);
    }

    
Subclasses can not override hashCode().

/**
     * Subclasses can not override hashCode().
     */
    @Override final public int hashCode() {
        return super.hashCode();
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder(128);
        DebugUtils.buildShortClassTag(this, sb);
        if (mIndex >= 0) {
            sb.append(" #");
            sb.append(mIndex);
        }
        if (mFragmentId != 0) {
            sb.append(" id=0x");
            sb.append(Integer.toHexString(mFragmentId));
        }
        if (mTag != null) {
            sb.append(" ");
            sb.append(mTag);
        }
        sb.append('}');
        return sb.toString();
    }

    
Return the identifier this fragment is known by.  This is either
the android:id value supplied in a layout or the container view ID
supplied when adding the fragment.

/**
     * Return the identifier this fragment is known by.  This is either
     * the android:id value supplied in a layout or the container view ID
     * supplied when adding the fragment.
     */
    final public int getId() {
        return mFragmentId;
    }

    
Get the tag name of the fragment, if specified.

/**
     * Get the tag name of the fragment, if specified.
     */
    final public String getTag() {
        return mTag;
    }

    
Supply the construction arguments for this fragment.
The arguments supplied here will be retained across fragment destroy and
creation.

This method cannot be called if the fragment is added to a FragmentManager and if isStateSaved() would return true. Prior to VERSION_CODES.O, this method may only be called if the fragment has not yet been added to a FragmentManager. 


/**
     * Supply the construction arguments for this fragment.
     * The arguments supplied here will be retained across fragment destroy and
     * creation.
     *
     * <p>This method cannot be called if the fragment is added to a FragmentManager and
     * if {@link #isStateSaved()} would return true. Prior to {@link Build.VERSION_CODES#O},
     * this method may only be called if the fragment has not yet been added to a FragmentManager.
     * </p>
     */
    public void setArguments(Bundle args) {
        // The isStateSaved requirement below was only added in Android O and is compatible
        // because it loosens previous requirements rather than making them more strict.
        // See method javadoc.
        if (mIndex >= 0 && isStateSaved()) {
            throw new IllegalStateException("Fragment already active");
        }
        mArguments = args;
    }

    
Return the arguments supplied to setArguments, if any. 
/**
     * Return the arguments supplied to {@link #setArguments}, if any.
     */
    final public Bundle getArguments() {
        return mArguments;
    }

    
Returns true if this fragment is added and its state has already been saved by its host. Any operations that would change saved state should not be performed if this method returns true, and some operations such as setArguments(Bundle) will fail. 
Returns:true if this fragment's state has already been saved by its host
/**
     * Returns true if this fragment is added and its state has already been saved
     * by its host. Any operations that would change saved state should not be performed
     * if this method returns true, and some operations such as {@link #setArguments(Bundle)}
     * will fail.
     *
     * @return true if this fragment's state has already been saved by its host
     */
    public final boolean isStateSaved() {
        if (mFragmentManager == null) {
            return false;
        }
        return mFragmentManager.isStateSaved();
    }

    
Set the initial saved state that this Fragment should restore itself from when first being constructed, as returned by 
FragmentManager.saveFragmentInstanceState. 
Params:
  • state – The state the fragment should be restored from.
/**
     * Set the initial saved state that this Fragment should restore itself
     * from when first being constructed, as returned by
     * {@link FragmentManager#saveFragmentInstanceState(Fragment)
     * FragmentManager.saveFragmentInstanceState}.
     *
     * @param state The state the fragment should be restored from.
     */
    public void setInitialSavedState(SavedState state) {
        if (mIndex >= 0) {
            throw new IllegalStateException("Fragment already active");
        }
        mSavedFragmentState = state != null && state.mState != null
                ? state.mState : null;
    }

    
Optional target for this fragment. This may be used, for example, if this fragment is being started by another, and when done wants to give a result back to the first. The target set here is retained across instances via 
FragmentManager.putFragment(). 
Params:
  • fragment – The fragment that is the target of this one.
  • requestCode – Optional request code, for convenience if you are going to call back with onActivityResult(int, int, Intent).
/**
     * Optional target for this fragment.  This may be used, for example,
     * if this fragment is being started by another, and when done wants to
     * give a result back to the first.  The target set here is retained
     * across instances via {@link FragmentManager#putFragment
     * FragmentManager.putFragment()}.
     *
     * @param fragment The fragment that is the target of this one.
     * @param requestCode Optional request code, for convenience if you
     * are going to call back with {@link #onActivityResult(int, int, Intent)}.
     */
    public void setTargetFragment(Fragment fragment, int requestCode) {
        // Don't allow a caller to set a target fragment in another FragmentManager,
        // but there's a snag: people do set target fragments before fragments get added.
        // We'll have the FragmentManager check that for validity when we move
        // the fragments to a valid state.
        final FragmentManager mine = getFragmentManager();
        final FragmentManager theirs = fragment != null ? fragment.getFragmentManager() : null;
        if (mine != null && theirs != null && mine != theirs) {
            throw new IllegalArgumentException("Fragment " + fragment
                    + " must share the same FragmentManager to be set as a target fragment");
        }

        // Don't let someone create a cycle.
        for (Fragment check = fragment; check != null; check = check.getTargetFragment()) {
            if (check == this) {
                throw new IllegalArgumentException("Setting " + fragment + " as the target of "
                        + this + " would create a target cycle");
            }
        }
        mTarget = fragment;
        mTargetRequestCode = requestCode;
    }

    
Return the target fragment set by setTargetFragment. 
/**
     * Return the target fragment set by {@link #setTargetFragment}.
     */
    final public Fragment getTargetFragment() {
        return mTarget;
    }

    
Return the target request code set by setTargetFragment. 
/**
     * Return the target request code set by {@link #setTargetFragment}.
     */
    final public int getTargetRequestCode() {
        return mTargetRequestCode;
    }

    
Return the Context this fragment is currently associated with. 
/**
     * Return the {@link Context} this fragment is currently associated with.
     */
    public Context getContext() {
        return mHost == null ? null : mHost.getContext();
    }

    
Return the Activity this fragment is currently associated with.

/**
     * Return the Activity this fragment is currently associated with.
     */
    final public Activity getActivity() {
        return mHost == null ? null : mHost.getActivity();
    }

    
Return the host object of this fragment. May return null if the fragment isn't currently being hosted. 
/**
     * Return the host object of this fragment. May return {@code null} if the fragment
     * isn't currently being hosted.
     */
    @Nullable
    final public Object getHost() {
        return mHost == null ? null : mHost.onGetHost();
    }

    
Return getActivity().getResources().

/**
     * Return <code>getActivity().getResources()</code>.
     */
    final public Resources getResources() {
        if (mHost == null) {
            throw new IllegalStateException("Fragment " + this + " not attached to Activity");
        }
        return mHost.getContext().getResources();
    }

    
Return a localized, styled CharSequence from the application's package's
default string table.

Params:
  • resId – Resource id for the CharSequence text
/**
     * Return a localized, styled CharSequence from the application's package's
     * default string table.
     *
     * @param resId Resource id for the CharSequence text
     */
    public final CharSequence getText(@StringRes int resId) {
        return getResources().getText(resId);
    }

    
Return a localized string from the application's package's
default string table.

Params:
  • resId – Resource id for the string
/**
     * Return a localized string from the application's package's
     * default string table.
     *
     * @param resId Resource id for the string
     */
    public final String getString(@StringRes int resId) {
        return getResources().getString(resId);
    }

    
Return a localized formatted string from the application's package's default string table, substituting the format arguments as defined in Formatter and String.format. 
Params:
  • resId – Resource id for the format string
  • formatArgs – The format arguments that will be used for substitution.
/**
     * Return a localized formatted string from the application's package's
     * default string table, substituting the format arguments as defined in
     * {@link java.util.Formatter} and {@link java.lang.String#format}.
     *
     * @param resId Resource id for the format string
     * @param formatArgs The format arguments that will be used for substitution.
     */

    public final String getString(@StringRes int resId, Object... formatArgs) {
        return getResources().getString(resId, formatArgs);
    }

    
Return the FragmentManager for interacting with fragments associated with this fragment's activity. Note that this will be non-null slightly before getActivity(), during the time from when the fragment is placed in a FragmentTransaction until it is committed and attached to its activity. 
If this Fragment is a child of another Fragment, the FragmentManager returned here will be the parent's getChildFragmentManager(). 
/**
     * Return the FragmentManager for interacting with fragments associated
     * with this fragment's activity.  Note that this will be non-null slightly
     * before {@link #getActivity()}, during the time from when the fragment is
     * placed in a {@link FragmentTransaction} until it is committed and
     * attached to its activity.
     *
     * <p>If this Fragment is a child of another Fragment, the FragmentManager
     * returned here will be the parent's {@link #getChildFragmentManager()}.
     */
    final public FragmentManager getFragmentManager() {
        return mFragmentManager;
    }

    
Return a private FragmentManager for placing and managing Fragments
inside of this Fragment.

/**
     * Return a private FragmentManager for placing and managing Fragments
     * inside of this Fragment.
     */
    final public FragmentManager getChildFragmentManager() {
        if (mChildFragmentManager == null) {
            instantiateChildFragmentManager();
            if (mState >= RESUMED) {
                mChildFragmentManager.dispatchResume();
            } else if (mState >= STARTED) {
                mChildFragmentManager.dispatchStart();
            } else if (mState >= ACTIVITY_CREATED) {
                mChildFragmentManager.dispatchActivityCreated();
            } else if (mState >= CREATED) {
                mChildFragmentManager.dispatchCreate();
            }
        }
        return mChildFragmentManager;
    }

    
Returns the parent Fragment containing this Fragment.  If this Fragment
is attached directly to an Activity, returns null.

/**
     * Returns the parent Fragment containing this Fragment.  If this Fragment
     * is attached directly to an Activity, returns null.
     */
    final public Fragment getParentFragment() {
        return mParentFragment;
    }

    
Return true if the fragment is currently added to its activity.

/**
     * Return true if the fragment is currently added to its activity.
     */
    final public boolean isAdded() {
        return mHost != null && mAdded;
    }

    
Return true if the fragment has been explicitly detached from the UI. That is, 
FragmentTransaction.detach(Fragment) has been used on it. 
/**
     * Return true if the fragment has been explicitly detached from the UI.
     * That is, {@link FragmentTransaction#detach(Fragment)
     * FragmentTransaction.detach(Fragment)} has been used on it.
     */
    final public boolean isDetached() {
        return mDetached;
    }

    
Return true if this fragment is currently being removed from its
activity.  This is  not whether its activity is finishing, but
rather whether it is in the process of being removed from its activity.

/**
     * Return true if this fragment is currently being removed from its
     * activity.  This is  <em>not</em> whether its activity is finishing, but
     * rather whether it is in the process of being removed from its activity.
     */
    final public boolean isRemoving() {
        return mRemoving;
    }

    
Return true if the layout is included as part of an activity view
hierarchy via the <fragment> tag.  This will always be true when
fragments are created through the <fragment> tag, except
in the case where an old fragment is restored from a previous state and
it does not appear in the layout of the current state.

/**
     * Return true if the layout is included as part of an activity view
     * hierarchy via the &lt;fragment&gt; tag.  This will always be true when
     * fragments are created through the &lt;fragment&gt; tag, <em>except</em>
     * in the case where an old fragment is restored from a previous state and
     * it does not appear in the layout of the current state.
     */
    final public boolean isInLayout() {
        return mInLayout;
    }

    
Return true if the fragment is in the resumed state. This is true for the duration of onResume() and onPause() as well. 
/**
     * Return true if the fragment is in the resumed state.  This is true
     * for the duration of {@link #onResume()} and {@link #onPause()} as well.
     */
    final public boolean isResumed() {
        return mState >= RESUMED;
    }

    
Return true if the fragment is currently visible to the user.  This means
it: (1) has been added, (2) has its view attached to the window, and
(3) is not hidden.

/**
     * Return true if the fragment is currently visible to the user.  This means
     * it: (1) has been added, (2) has its view attached to the window, and
     * (3) is not hidden.
     */
    final public boolean isVisible() {
        return isAdded() && !isHidden() && mView != null
                && mView.getWindowToken() != null && mView.getVisibility() == View.VISIBLE;
    }

    
Return true if the fragment has been hidden. By default fragments are shown. You can find out about changes to this state with onHiddenChanged. Note that the hidden state is orthogonal to other states -- that is, to be visible to the user, a fragment must be both started and not hidden. 
/**
     * Return true if the fragment has been hidden.  By default fragments
     * are shown.  You can find out about changes to this state with
     * {@link #onHiddenChanged}.  Note that the hidden state is orthogonal
     * to other states -- that is, to be visible to the user, a fragment
     * must be both started and not hidden.
     */
    final public boolean isHidden() {
        return mHidden;
    }

    
Called when the hidden state (as returned by isHidden() of the fragment has changed. Fragments start out not hidden; this will be called whenever the fragment changes state from that. 
Params:
  • hidden – True if the fragment is now hidden, false otherwise.
/**
     * Called when the hidden state (as returned by {@link #isHidden()} of
     * the fragment has changed.  Fragments start out not hidden; this will
     * be called whenever the fragment changes state from that.
     * @param hidden True if the fragment is now hidden, false otherwise.
     */
    public void onHiddenChanged(boolean hidden) {
    }

    
Control whether a fragment instance is retained across Activity
re-creation (such as from a configuration change).  This can only
be used with fragments not in the back stack.  If set, the fragment
lifecycle will be slightly different when an activity is recreated:


/**
     * Control whether a fragment instance is retained across Activity
     * re-creation (such as from a configuration change).  This can only
     * be used with fragments not in the back stack.  If set, the fragment
     * lifecycle will be slightly different when an activity is recreated:
     * <ul>
     * <li> {@link #onDestroy()} will not be called (but {@link #onDetach()} still
     * will be, because the fragment is being detached from its current activity).
     * <li> {@link #onCreate(Bundle)} will not be called since the fragment
     * is not being re-created.
     * <li> {@link #onAttach(Activity)} and {@link #onActivityCreated(Bundle)} <b>will</b>
     * still be called.
     * </ul>
     */
    public void setRetainInstance(boolean retain) {
        mRetainInstance = retain;
    }

    final public boolean getRetainInstance() {
        return mRetainInstance;
    }

    
Report that this fragment would like to participate in populating the options menu by receiving a call to onCreateOptionsMenu and related methods. 
Params:
  • hasMenu – If true, the fragment has menu items to contribute.
/**
     * Report that this fragment would like to participate in populating
     * the options menu by receiving a call to {@link #onCreateOptionsMenu}
     * and related methods.
     *
     * @param hasMenu If true, the fragment has menu items to contribute.
     */
    public void setHasOptionsMenu(boolean hasMenu) {
        if (mHasMenu != hasMenu) {
            mHasMenu = hasMenu;
            if (isAdded() && !isHidden()) {
                mFragmentManager.invalidateOptionsMenu();
            }
        }
    }

    
Set a hint for whether this fragment's menu should be visible.  This
is useful if you know that a fragment has been placed in your view
hierarchy so that the user can not currently seen it, so any menu items
it has should also not be shown.

Params:
  • menuVisible – The default is true, meaning the fragment's menu will
be shown as usual.  If false, the user will not see the menu.
/**
     * Set a hint for whether this fragment's menu should be visible.  This
     * is useful if you know that a fragment has been placed in your view
     * hierarchy so that the user can not currently seen it, so any menu items
     * it has should also not be shown.
     *
     * @param menuVisible The default is true, meaning the fragment's menu will
     * be shown as usual.  If false, the user will not see the menu.
     */
    public void setMenuVisibility(boolean menuVisible) {
        if (mMenuVisible != menuVisible) {
            mMenuVisible = menuVisible;
            if (mHasMenu && isAdded() && !isHidden()) {
                mFragmentManager.invalidateOptionsMenu();
            }
        }
    }

    
Set a hint to the system about whether this fragment's UI is currently visible
to the user. This hint defaults to true and is persistent across fragment instance
state save and restore.

An app may set this to false to indicate that the fragment's UI is
scrolled out of visibility or is otherwise not directly visible to the user.
This may be used by the system to prioritize operations such as fragment lifecycle updates
or loader ordering behavior.


Note: This method may be called outside of the fragment lifecycle
and thus has no ordering guarantees with regard to fragment lifecycle method calls.


Note: Prior to Android N there was a platform bug that could cause
setUserVisibleHint to bring a fragment up to the started state before its
FragmentTransaction had been committed. As some apps relied on this behavior,
it is preserved for apps that declare a targetSdkVersion of 23 or lower.


Params:
  • isVisibleToUser – true if this fragment's UI is currently visible to the user (default),
                       false if it is not.
/**
     * Set a hint to the system about whether this fragment's UI is currently visible
     * to the user. This hint defaults to true and is persistent across fragment instance
     * state save and restore.
     *
     * <p>An app may set this to false to indicate that the fragment's UI is
     * scrolled out of visibility or is otherwise not directly visible to the user.
     * This may be used by the system to prioritize operations such as fragment lifecycle updates
     * or loader ordering behavior.</p>
     *
     * <p><strong>Note:</strong> This method may be called outside of the fragment lifecycle
     * and thus has no ordering guarantees with regard to fragment lifecycle method calls.</p>
     *
     * <p><strong>Note:</strong> Prior to Android N there was a platform bug that could cause
     * <code>setUserVisibleHint</code> to bring a fragment up to the started state before its
     * <code>FragmentTransaction</code> had been committed. As some apps relied on this behavior,
     * it is preserved for apps that declare a <code>targetSdkVersion</code> of 23 or lower.</p>
     *
     * @param isVisibleToUser true if this fragment's UI is currently visible to the user (default),
     *                        false if it is not.
     */
    public void setUserVisibleHint(boolean isVisibleToUser) {
        // Prior to Android N we were simply checking if this fragment had a FragmentManager
        // set before we would trigger a deferred start. Unfortunately this also gets set before
        // a fragment transaction is committed, so if setUserVisibleHint was called before a
        // transaction commit, we would start the fragment way too early. FragmentPagerAdapter
        // triggers this situation.
        // Unfortunately some apps relied on this timing in overrides of setUserVisibleHint
        // on their own fragments, and expected, however erroneously, that after a call to
        // super.setUserVisibleHint their onStart methods had been run.
        // We preserve this behavior for apps targeting old platform versions below.
        boolean useBrokenAddedCheck = false;
        Context context = getContext();
        if (mFragmentManager != null && mFragmentManager.mHost != null) {
            context = mFragmentManager.mHost.getContext();
        }
        if (context != null) {
            useBrokenAddedCheck = context.getApplicationInfo().targetSdkVersion <= VERSION_CODES.M;
        }

        final boolean performDeferredStart;
        if (useBrokenAddedCheck) {
            performDeferredStart = !mUserVisibleHint && isVisibleToUser && mState < STARTED
                    && mFragmentManager != null;
        } else {
            performDeferredStart = !mUserVisibleHint && isVisibleToUser && mState < STARTED
                    && mFragmentManager != null && isAdded();
        }

        if (performDeferredStart) {
            mFragmentManager.performPendingDeferredStart(this);
        }

        mUserVisibleHint = isVisibleToUser;
        mDeferStart = mState < STARTED && !isVisibleToUser;
    }

    
See Also:
Returns:The current value of the user-visible hint on this fragment.
/**
     * @return The current value of the user-visible hint on this fragment.
     * @see #setUserVisibleHint(boolean)
     */
    public boolean getUserVisibleHint() {
        return mUserVisibleHint;
    }

    
Return the LoaderManager for this fragment, creating it if needed.

Deprecated:Use getLoaderManager.getLoaderManager()
/**
     * Return the LoaderManager for this fragment, creating it if needed.
     *
     * @deprecated Use {@link android.support.v4.app.Fragment#getLoaderManager()}
     */
    @Deprecated
    public LoaderManager getLoaderManager() {
        if (mLoaderManager != null) {
            return mLoaderManager;
        }
        if (mHost == null) {
            throw new IllegalStateException("Fragment " + this + " not attached to Activity");
        }
        mCheckedForLoaderManager = true;
        mLoaderManager = mHost.getLoaderManager(mWho, mLoadersStarted, true);
        return mLoaderManager;
    }

    
Call Activity.startActivity(Intent) from the fragment's containing Activity. 
Params:
  • intent – The intent to start.
/**
     * Call {@link Activity#startActivity(Intent)} from the fragment's
     * containing Activity.
     *
     * @param intent The intent to start.
     */
    public void startActivity(Intent intent) {
        startActivity(intent, null);
    }

    
Call Activity.startActivity(Intent, Bundle) from the fragment's containing Activity. 
Params:
  • intent – The intent to start.
  • options – Additional options for how the Activity should be started. See Context.startActivity(Intent, Bundle) Context.startActivity(Intent, Bundle)} for more details.
/**
     * Call {@link Activity#startActivity(Intent, Bundle)} from the fragment's
     * containing Activity.
     *
     * @param intent The intent to start.
     * @param options Additional options for how the Activity should be started.
     * See {@link android.content.Context#startActivity(Intent, Bundle)}
     * Context.startActivity(Intent, Bundle)} for more details.
     */
    public void startActivity(Intent intent, Bundle options) {
        if (mHost == null) {
            throw new IllegalStateException("Fragment " + this + " not attached to Activity");
        }
        if (options != null) {
            mHost.onStartActivityFromFragment(this, intent, -1, options);
        } else {
            // Note we want to go through this call for compatibility with
            // applications that may have overridden the method.
            mHost.onStartActivityFromFragment(this, intent, -1, null /*options*/);
        }
    }

    
Call Activity.startActivityForResult(Intent, int) from the fragment's containing Activity. 
/**
     * Call {@link Activity#startActivityForResult(Intent, int)} from the fragment's
     * containing Activity.
     */
    public void startActivityForResult(Intent intent, int requestCode) {
        startActivityForResult(intent, requestCode, null);
    }

    
Call Activity.startActivityForResult(Intent, int, Bundle) from the fragment's containing Activity. 
/**
     * Call {@link Activity#startActivityForResult(Intent, int, Bundle)} from the fragment's
     * containing Activity.
     */
    public void startActivityForResult(Intent intent, int requestCode, Bundle options) {
        if (mHost == null) {
            throw new IllegalStateException("Fragment " + this + " not attached to Activity");
        }
        mHost.onStartActivityFromFragment(this, intent, requestCode, options);
    }

    
@hide Call Activity.startActivityForResultAsUser(Intent, int, UserHandle) from the fragment's containing Activity.
/**
     * @hide
     * Call {@link Activity#startActivityForResultAsUser(Intent, int, UserHandle)} from the
     * fragment's containing Activity.
     */
    public void startActivityForResultAsUser(
            Intent intent, int requestCode, Bundle options, UserHandle user) {
        if (mHost == null) {
            throw new IllegalStateException("Fragment " + this + " not attached to Activity");
        }
        mHost.onStartActivityAsUserFromFragment(this, intent, requestCode, options, user);
    }

    /**
     * Call {@link Activity#startIntentSenderForResult(IntentSender, int, Intent, int, int, int,
     * Bundle)} from the fragment's containing Activity.
     */
    public void startIntentSenderForResult(IntentSender intent, int requestCode,
            @Nullable Intent fillInIntent, int flagsMask, int flagsValues, int extraFlags,
            Bundle options) throws IntentSender.SendIntentException {
        if (mHost == null) {
            throw new IllegalStateException("Fragment " + this + " not attached to Activity");
        }
        mHost.onStartIntentSenderFromFragment(this, intent, requestCode, fillInIntent, flagsMask,
                flagsValues, extraFlags, options);
    }

    
Receive the result from a previous call to startActivityForResult(Intent, int). This follows the related Activity API as described there in Activity.onActivityResult(int, int, Intent). 
Params:
  • requestCode – The integer request code originally supplied to
                   startActivityForResult(), allowing you to identify who this
                   result came from.
  • resultCode – The integer result code returned by the child activity
                  through its setResult().
  • data – An Intent, which can return result data to the caller
              (various data can be attached to Intent "extras").
/**
     * Receive the result from a previous call to
     * {@link #startActivityForResult(Intent, int)}.  This follows the
     * related Activity API as described there in
     * {@link Activity#onActivityResult(int, int, Intent)}.
     *
     * @param requestCode The integer request code originally supplied to
     *                    startActivityForResult(), allowing you to identify who this
     *                    result came from.
     * @param resultCode The integer result code returned by the child activity
     *                   through its setResult().
     * @param data An Intent, which can return result data to the caller
     *               (various data can be attached to Intent "extras").
     */
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
    }

    
Requests permissions to be granted to this application. These permissions must be requested in your manifest, they should not be granted to your app, and they should have protection level dangerous, regardless whether they are declared by the platform or a third-party app. 
 Normal permissions PermissionInfo.PROTECTION_NORMAL are granted at install time if requested in the manifest. Signature permissions PermissionInfo.PROTECTION_SIGNATURE are granted at install time if requested in the manifest and the signature of your app matches the signature of the app declaring the permissions. 


 If your app does not have the requested permissions the user will be presented with UI for accepting them. After the user has accepted or rejected the requested permissions you will receive a callback on onRequestPermissionsResult(int, String[], int[]) reporting whether the permissions were granted or not. 



Note that requesting a permission does not guarantee it will be granted and
your app should be able to run without having this permission.



 This method may start an activity allowing the user to choose which permissions to grant and which to reject. Hence, you should be prepared that your activity may be paused and resumed. Further, granting some permissions may require a restart of you application. In such a case, the system will recreate the activity stack before delivering the result to onRequestPermissionsResult(int, String[], int[]). 


 When checking whether you have a permission you should use Context.checkSelfPermission(String). 



Calling this API for permissions already granted to your app would show UI
to the user to decide whether the app can still hold these permissions. This
can be useful if the way your app uses data guarded by the permissions
changes significantly.



 You cannot request a permission if your activity sets noHistory to true because in this case the activity would not receive result callbacks including onRequestPermissionsResult(int, String[], int[]). 



A sample permissions request looks like this:



 private void showContacts() { if (getActivity().checkSelfPermission(Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED) { requestPermissions(new String[]{Manifest.permission.READ_CONTACTS}, PERMISSIONS_REQUEST_READ_CONTACTS); } else { doShowContacts(); } } @Override public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) { if (requestCode == PERMISSIONS_REQUEST_READ_CONTACTS && grantResults[0] == PackageManager.PERMISSION_GRANTED) { doShowContacts(); } } 


Params:
See Also:
/**
     * Requests permissions to be granted to this application. These permissions
     * must be requested in your manifest, they should not be granted to your app,
     * and they should have protection level {@link android.content.pm.PermissionInfo
     * #PROTECTION_DANGEROUS dangerous}, regardless whether they are declared by
     * the platform or a third-party app.
     * <p>
     * Normal permissions {@link android.content.pm.PermissionInfo#PROTECTION_NORMAL}
     * are granted at install time if requested in the manifest. Signature permissions
     * {@link android.content.pm.PermissionInfo#PROTECTION_SIGNATURE} are granted at
     * install time if requested in the manifest and the signature of your app matches
     * the signature of the app declaring the permissions.
     * </p>
     * <p>
     * If your app does not have the requested permissions the user will be presented
     * with UI for accepting them. After the user has accepted or rejected the
     * requested permissions you will receive a callback on {@link
     * #onRequestPermissionsResult(int, String[], int[])} reporting whether the
     * permissions were granted or not.
     * </p>
     * <p>
     * Note that requesting a permission does not guarantee it will be granted and
     * your app should be able to run without having this permission.
     * </p>
     * <p>
     * This method may start an activity allowing the user to choose which permissions
     * to grant and which to reject. Hence, you should be prepared that your activity
     * may be paused and resumed. Further, granting some permissions may require
     * a restart of you application. In such a case, the system will recreate the
     * activity stack before delivering the result to {@link
     * #onRequestPermissionsResult(int, String[], int[])}.
     * </p>
     * <p>
     * When checking whether you have a permission you should use {@link
     * android.content.Context#checkSelfPermission(String)}.
     * </p>
     * <p>
     * Calling this API for permissions already granted to your app would show UI
     * to the user to decide whether the app can still hold these permissions. This
     * can be useful if the way your app uses data guarded by the permissions
     * changes significantly.
     * </p>
     * <p>
     * You cannot request a permission if your activity sets {@link
     * android.R.styleable#AndroidManifestActivity_noHistory noHistory} to
     * <code>true</code> because in this case the activity would not receive
     * result callbacks including {@link #onRequestPermissionsResult(int, String[], int[])}.
     * </p>
     * <p>
     * A sample permissions request looks like this:
     * </p>
     * <code><pre><p>
     * private void showContacts() {
     *     if (getActivity().checkSelfPermission(Manifest.permission.READ_CONTACTS)
     *             != PackageManager.PERMISSION_GRANTED) {
     *         requestPermissions(new String[]{Manifest.permission.READ_CONTACTS},
     *                 PERMISSIONS_REQUEST_READ_CONTACTS);
     *     } else {
     *         doShowContacts();
     *     }
     * }
     *
     * {@literal @}Override
     * public void onRequestPermissionsResult(int requestCode, String[] permissions,
     *         int[] grantResults) {
     *     if (requestCode == PERMISSIONS_REQUEST_READ_CONTACTS
     *             && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
     *         doShowContacts();
     *     }
     * }
     * </code></pre></p>
     *
     * @param permissions The requested permissions. Must me non-null and not empty.
     * @param requestCode Application specific request code to match with a result
     *    reported to {@link #onRequestPermissionsResult(int, String[], int[])}.
     *    Should be >= 0.
     *
     * @see #onRequestPermissionsResult(int, String[], int[])
     * @see android.content.Context#checkSelfPermission(String)
     */
    public final void requestPermissions(@NonNull String[] permissions, int requestCode) {
        if (mHost == null) {
            throw new IllegalStateException("Fragment " + this + " not attached to Activity");
        }
        mHost.onRequestPermissionsFromFragment(this, permissions,requestCode);
    }

    
Callback for the result from requesting permissions. This method is invoked for every call on requestPermissions(String[], int). 

Note: It is possible that the permissions request interaction
with the user is interrupted. In this case you will receive empty permissions
and results arrays which should be treated as a cancellation.



Params:
See Also:
/**
     * Callback for the result from requesting permissions. This method
     * is invoked for every call on {@link #requestPermissions(String[], int)}.
     * <p>
     * <strong>Note:</strong> It is possible that the permissions request interaction
     * with the user is interrupted. In this case you will receive empty permissions
     * and results arrays which should be treated as a cancellation.
     * </p>
     *
     * @param requestCode The request code passed in {@link #requestPermissions(String[], int)}.
     * @param permissions The requested permissions. Never null.
     * @param grantResults The grant results for the corresponding permissions
     *     which is either {@link android.content.pm.PackageManager#PERMISSION_GRANTED}
     *     or {@link android.content.pm.PackageManager#PERMISSION_DENIED}. Never null.
     *
     * @see #requestPermissions(String[], int)
     */
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
            @NonNull int[] grantResults) {
        /* callback - do nothing */
    }

    
Gets whether you should show UI with rationale for requesting a permission.
You should do this only if you do not have the permission and the context in
which the permission is requested does not clearly communicate to the user
what would be the benefit from granting this permission.


For example, if you write a camera app, requesting the camera permission
would be expected by the user and no rationale for why it is requested is
needed. If however, the app needs location for tagging photos then a non-tech
savvy user may wonder how location is related to taking photos. In this case
you may choose to show UI with rationale of requesting this permission.



Params:
  • permission – A permission your app wants to request.
See Also:
Returns:Whether you can show permission rationale UI.
/**
     * Gets whether you should show UI with rationale for requesting a permission.
     * You should do this only if you do not have the permission and the context in
     * which the permission is requested does not clearly communicate to the user
     * what would be the benefit from granting this permission.
     * <p>
     * For example, if you write a camera app, requesting the camera permission
     * would be expected by the user and no rationale for why it is requested is
     * needed. If however, the app needs location for tagging photos then a non-tech
     * savvy user may wonder how location is related to taking photos. In this case
     * you may choose to show UI with rationale of requesting this permission.
     * </p>
     *
     * @param permission A permission your app wants to request.
     * @return Whether you can show permission rationale UI.
     *
     * @see Context#checkSelfPermission(String)
     * @see #requestPermissions(String[], int)
     * @see #onRequestPermissionsResult(int, String[], int[])
     */
    public boolean shouldShowRequestPermissionRationale(@NonNull String permission) {
        if (mHost != null) {
            return mHost.getContext().getPackageManager()
                    .shouldShowRequestPermissionRationale(permission);
        }
        return false;
    }

    
Returns the LayoutInflater used to inflate Views of this Fragment. The default
implementation will throw an exception if the Fragment is not attached.

Returns:The LayoutInflater used to inflate Views of this Fragment.
/**
     * Returns the LayoutInflater used to inflate Views of this Fragment. The default
     * implementation will throw an exception if the Fragment is not attached.
     *
     * @return The LayoutInflater used to inflate Views of this Fragment.
     */
    public LayoutInflater onGetLayoutInflater(Bundle savedInstanceState) {
        if (mHost == null) {
            throw new IllegalStateException("onGetLayoutInflater() cannot be executed until the "
                    + "Fragment is attached to the FragmentManager.");
        }
        final LayoutInflater result = mHost.onGetLayoutInflater();
        if (mHost.onUseFragmentManagerInflaterFactory()) {
            getChildFragmentManager(); // Init if needed; use raw implementation below.
            result.setPrivateFactory(mChildFragmentManager.getLayoutInflaterFactory());
        }
        return result;
    }

    
Returns the cached LayoutInflater used to inflate Views of this Fragment. If onGetLayoutInflater(Bundle) has not been called onGetLayoutInflater(Bundle) will be called with a null argument and that value will be cached. 
 The cached LayoutInflater will be replaced immediately prior to onCreateView(LayoutInflater, ViewGroup, Bundle) and cleared immediately after onDetach(). 
Returns:The LayoutInflater used to inflate Views of this Fragment.
/**
     * Returns the cached LayoutInflater used to inflate Views of this Fragment. If
     * {@link #onGetLayoutInflater(Bundle)} has not been called {@link #onGetLayoutInflater(Bundle)}
     * will be called with a {@code null} argument and that value will be cached.
     * <p>
     * The cached LayoutInflater will be replaced immediately prior to
     * {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)} and cleared immediately after
     * {@link #onDetach()}.
     *
     * @return The LayoutInflater used to inflate Views of this Fragment.
     */
    public final LayoutInflater getLayoutInflater() {
        if (mLayoutInflater == null) {
            return performGetLayoutInflater(null);
        }
        return mLayoutInflater;
    }

    
Calls onGetLayoutInflater(Bundle) and caches the result for use by getLayoutInflater(). 
Params:
  • savedInstanceState – If the fragment is being re-created from
a previous saved state, this is the state.
Returns:The LayoutInflater used to inflate Views of this Fragment.
/**
     * Calls {@link #onGetLayoutInflater(Bundle)} and caches the result for use by
     * {@link #getLayoutInflater()}.
     *
     * @param savedInstanceState If the fragment is being re-created from
     * a previous saved state, this is the state.
     * @return The LayoutInflater used to inflate Views of this Fragment.
     */
    LayoutInflater performGetLayoutInflater(Bundle savedInstanceState) {
        LayoutInflater layoutInflater = onGetLayoutInflater(savedInstanceState);
        mLayoutInflater = layoutInflater;
        return mLayoutInflater;
    }

    
Deprecated:Use onInflate(Context, AttributeSet, Bundle) instead.
/**
     * @deprecated Use {@link #onInflate(Context, AttributeSet, Bundle)} instead.
     */
    @Deprecated
    @CallSuper
    public void onInflate(AttributeSet attrs, Bundle savedInstanceState) {
        mCalled = true;
    }

    
Called when a fragment is being created as part of a view layout
inflation, typically from setting the content view of an activity.  This
may be called immediately after the fragment is created from a 
tag in a layout file.  Note this is before the fragment's onAttach(Activity) has been called; all you should do here is parse the attributes and save them away. 
This is called every time the fragment is inflated, even if it is
being inflated into a new instance with saved state.  It typically makes
sense to re-parse the parameters each time, to allow them to change with
different configurations.


Here is a typical implementation of a fragment that can take parameters both through attributes supplied here as well from getArguments():

{@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentArguments.java
     fragment}

Note that parsing the XML attributes uses a "styleable" resource.  The
declaration for the styleable used here is:

{@sample development/samples/ApiDemos/res/values/attrs.xml fragment_arguments}

The fragment can then be declared within its activity's content layout
through a tag like this:

{@sample development/samples/ApiDemos/res/layout/fragment_arguments.xml from_attributes}

This fragment can also be created dynamically from arguments given
at runtime in the arguments Bundle; here is an example of doing so at
creation of the containing activity:

{@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentArguments.java
     create}

Params:
  • context – The Context that is inflating this fragment.
  • attrs – The attributes at the tag where the fragment is
being created.
  • savedInstanceState – If the fragment is being re-created from
a previous saved state, this is the state.
/**
     * Called when a fragment is being created as part of a view layout
     * inflation, typically from setting the content view of an activity.  This
     * may be called immediately after the fragment is created from a <fragment>
     * tag in a layout file.  Note this is <em>before</em> the fragment's
     * {@link #onAttach(Activity)} has been called; all you should do here is
     * parse the attributes and save them away.
     *
     * <p>This is called every time the fragment is inflated, even if it is
     * being inflated into a new instance with saved state.  It typically makes
     * sense to re-parse the parameters each time, to allow them to change with
     * different configurations.</p>
     *
     * <p>Here is a typical implementation of a fragment that can take parameters
     * both through attributes supplied here as well from {@link #getArguments()}:</p>
     *
     * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentArguments.java
     *      fragment}
     *
     * <p>Note that parsing the XML attributes uses a "styleable" resource.  The
     * declaration for the styleable used here is:</p>
     *
     * {@sample development/samples/ApiDemos/res/values/attrs.xml fragment_arguments}
     *
     * <p>The fragment can then be declared within its activity's content layout
     * through a tag like this:</p>
     *
     * {@sample development/samples/ApiDemos/res/layout/fragment_arguments.xml from_attributes}
     *
     * <p>This fragment can also be created dynamically from arguments given
     * at runtime in the arguments Bundle; here is an example of doing so at
     * creation of the containing activity:</p>
     *
     * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentArguments.java
     *      create}
     *
     * @param context The Context that is inflating this fragment.
     * @param attrs The attributes at the tag where the fragment is
     * being created.
     * @param savedInstanceState If the fragment is being re-created from
     * a previous saved state, this is the state.
     */
    @CallSuper
    public void onInflate(Context context, AttributeSet attrs, Bundle savedInstanceState) {
        onInflate(attrs, savedInstanceState);
        mCalled = true;

        TypedArray a = context.obtainStyledAttributes(attrs,
                com.android.internal.R.styleable.Fragment);
        setEnterTransition(loadTransition(context, a, getEnterTransition(), null,
                com.android.internal.R.styleable.Fragment_fragmentEnterTransition));
        setReturnTransition(loadTransition(context, a, getReturnTransition(),
                USE_DEFAULT_TRANSITION,
                com.android.internal.R.styleable.Fragment_fragmentReturnTransition));
        setExitTransition(loadTransition(context, a, getExitTransition(), null,
                com.android.internal.R.styleable.Fragment_fragmentExitTransition));

        setReenterTransition(loadTransition(context, a, getReenterTransition(),
                USE_DEFAULT_TRANSITION,
                com.android.internal.R.styleable.Fragment_fragmentReenterTransition));
        setSharedElementEnterTransition(loadTransition(context, a,
                getSharedElementEnterTransition(), null,
                com.android.internal.R.styleable.Fragment_fragmentSharedElementEnterTransition));
        setSharedElementReturnTransition(loadTransition(context, a,
                getSharedElementReturnTransition(), USE_DEFAULT_TRANSITION,
                com.android.internal.R.styleable.Fragment_fragmentSharedElementReturnTransition));
        boolean isEnterSet;
        boolean isReturnSet;
        if (mAnimationInfo == null) {
            isEnterSet = false;
            isReturnSet = false;
        } else {
            isEnterSet = mAnimationInfo.mAllowEnterTransitionOverlap != null;
            isReturnSet = mAnimationInfo.mAllowReturnTransitionOverlap != null;
        }
        if (!isEnterSet) {
            setAllowEnterTransitionOverlap(a.getBoolean(
                    com.android.internal.R.styleable.Fragment_fragmentAllowEnterTransitionOverlap,
                    true));
        }
        if (!isReturnSet) {
            setAllowReturnTransitionOverlap(a.getBoolean(
                    com.android.internal.R.styleable.Fragment_fragmentAllowReturnTransitionOverlap,
                    true));
        }
        a.recycle();

        final Activity hostActivity = mHost == null ? null : mHost.getActivity();
        if (hostActivity != null) {
            mCalled = false;
            onInflate(hostActivity, attrs, savedInstanceState);
        }
    }

    
Deprecated:Use onInflate(Context, AttributeSet, Bundle) instead.
/**
     * @deprecated Use {@link #onInflate(Context, AttributeSet, Bundle)} instead.
     */
    @Deprecated
    @CallSuper
    public void onInflate(Activity activity, AttributeSet attrs, Bundle savedInstanceState) {
        mCalled = true;
    }

    
Called when a fragment is attached as a child of this fragment.

This is called after the attached fragment's onAttach and before
the attached fragment's onCreate if the fragment has not yet had a previous
call to onCreate.


Params:
  • childFragment – child fragment being attached
/**
     * Called when a fragment is attached as a child of this fragment.
     *
     * <p>This is called after the attached fragment's <code>onAttach</code> and before
     * the attached fragment's <code>onCreate</code> if the fragment has not yet had a previous
     * call to <code>onCreate</code>.</p>
     *
     * @param childFragment child fragment being attached
     */
    public void onAttachFragment(Fragment childFragment) {
    }

    
Called when a fragment is first attached to its context. onCreate(Bundle) will be called after this. 
/**
     * Called when a fragment is first attached to its context.
     * {@link #onCreate(Bundle)} will be called after this.
     */
    @CallSuper
    public void onAttach(Context context) {
        mCalled = true;
        final Activity hostActivity = mHost == null ? null : mHost.getActivity();
        if (hostActivity != null) {
            mCalled = false;
            onAttach(hostActivity);
        }
    }

    
Deprecated:Use onAttach(Context) instead.
/**
     * @deprecated Use {@link #onAttach(Context)} instead.
     */
    @Deprecated
    @CallSuper
    public void onAttach(Activity activity) {
        mCalled = true;
    }

    
Called when a fragment loads an animation.

/**
     * Called when a fragment loads an animation.
     */
    public Animator onCreateAnimator(int transit, boolean enter, int nextAnim) {
        return null;
    }

    
Called to do initial creation of a fragment. This is called after onAttach(Activity) and before onCreateView(LayoutInflater, ViewGroup, Bundle), but is not called if the fragment instance is retained across Activity re-creation (see setRetainInstance(boolean)). 
Note that this can be called while the fragment's activity is still in the process of being created. As such, you can not rely on things like the activity's content view hierarchy being initialized at this point. If you want to do work once the activity itself is created, see onActivityCreated(Bundle). 
If your app's targetSdkVersion is VERSION_CODES.M or lower, child fragments being restored from the savedInstanceState are restored after onCreate returns. When targeting VERSION_CODES.N or above and running on an N or newer platform version they are restored by Fragment.onCreate.


Params:
  • savedInstanceState – If the fragment is being re-created from
a previous saved state, this is the state.
/**
     * Called to do initial creation of a fragment.  This is called after
     * {@link #onAttach(Activity)} and before
     * {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}, but is not called if the fragment
     * instance is retained across Activity re-creation (see {@link #setRetainInstance(boolean)}).
     *
     * <p>Note that this can be called while the fragment's activity is
     * still in the process of being created.  As such, you can not rely
     * on things like the activity's content view hierarchy being initialized
     * at this point.  If you want to do work once the activity itself is
     * created, see {@link #onActivityCreated(Bundle)}.
     *
     * <p>If your app's <code>targetSdkVersion</code> is {@link android.os.Build.VERSION_CODES#M}
     * or lower, child fragments being restored from the savedInstanceState are restored after
     * <code>onCreate</code> returns. When targeting {@link android.os.Build.VERSION_CODES#N} or
     * above and running on an N or newer platform version
     * they are restored by <code>Fragment.onCreate</code>.</p>
     *
     * @param savedInstanceState If the fragment is being re-created from
     * a previous saved state, this is the state.
     */
    @CallSuper
    public void onCreate(@Nullable Bundle savedInstanceState) {
        mCalled = true;
        final Context context = getContext();
        final int version = context != null ? context.getApplicationInfo().targetSdkVersion : 0;
        if (version >= Build.VERSION_CODES.N) {
            restoreChildFragmentState(savedInstanceState, true);
            if (mChildFragmentManager != null
                    && !mChildFragmentManager.isStateAtLeast(Fragment.CREATED)) {
                mChildFragmentManager.dispatchCreate();
            }
        }
    }

    void restoreChildFragmentState(@Nullable Bundle savedInstanceState, boolean provideNonConfig) {
        if (savedInstanceState != null) {
            Parcelable p = savedInstanceState.getParcelable(Activity.FRAGMENTS_TAG);
            if (p != null) {
                if (mChildFragmentManager == null) {
                    instantiateChildFragmentManager();
                }
                mChildFragmentManager.restoreAllState(p, provideNonConfig ? mChildNonConfig : null);
                mChildNonConfig = null;
                mChildFragmentManager.dispatchCreate();
            }
        }
    }

    
Called to have the fragment instantiate its user interface view. This is optional, and non-graphical fragments can return null (which is the default implementation). This will be called between onCreate(Bundle) and onActivityCreated(Bundle). 
If you return a View from here, you will later be called in onDestroyView when the view is being released. 
Params:
  • inflater – The LayoutInflater object that can be used to inflate
any views in the fragment,
  • container – If non-null, this is the parent view that the fragment's
UI should be attached to.  The fragment should not add the view itself,
but this can be used to generate the LayoutParams of the view.
  • savedInstanceState – If non-null, this fragment is being re-constructed
from a previous saved state as given here.
Returns:Return the View for the fragment's UI, or null.
/**
     * Called to have the fragment instantiate its user interface view.
     * This is optional, and non-graphical fragments can return null (which
     * is the default implementation).  This will be called between
     * {@link #onCreate(Bundle)} and {@link #onActivityCreated(Bundle)}.
     *
     * <p>If you return a View from here, you will later be called in
     * {@link #onDestroyView} when the view is being released.
     *
     * @param inflater The LayoutInflater object that can be used to inflate
     * any views in the fragment,
     * @param container If non-null, this is the parent view that the fragment's
     * UI should be attached to.  The fragment should not add the view itself,
     * but this can be used to generate the LayoutParams of the view.
     * @param savedInstanceState If non-null, this fragment is being re-constructed
     * from a previous saved state as given here.
     *
     * @return Return the View for the fragment's UI, or null.
     */
    @Nullable
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
            Bundle savedInstanceState) {
        return null;
    }

    
Called immediately after onCreateView(LayoutInflater, ViewGroup, Bundle) has returned, but before any saved state has been restored in to the view. This gives subclasses a chance to initialize themselves once they know their view hierarchy has been completely created. The fragment's view hierarchy is not however attached to its parent at this point. 
Params:
/**
     * Called immediately after {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}
     * has returned, but before any saved state has been restored in to the view.
     * This gives subclasses a chance to initialize themselves once
     * they know their view hierarchy has been completely created.  The fragment's
     * view hierarchy is not however attached to its parent at this point.
     * @param view The View returned by {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}.
     * @param savedInstanceState If non-null, this fragment is being re-constructed
     * from a previous saved state as given here.
     */
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    }

    
Get the root view for the fragment's layout (the one returned by onCreateView), if provided. 
Returns:The fragment's root view, or null if it has no layout.
/**
     * Get the root view for the fragment's layout (the one returned by {@link #onCreateView}),
     * if provided.
     *
     * @return The fragment's root view, or null if it has no layout.
     */
    @Nullable
    public View getView() {
        return mView;
    }

    
Called when the fragment's activity has been created and this fragment's view hierarchy instantiated. It can be used to do final initialization once these pieces are in place, such as retrieving views or restoring state. It is also useful for fragments that use setRetainInstance(boolean) to retain their instance, as this callback tells the fragment when it is fully associated with the new activity instance. This is called after onCreateView and before onViewStateRestored(Bundle). 
Params:
  • savedInstanceState – If the fragment is being re-created from
a previous saved state, this is the state.
/**
     * Called when the fragment's activity has been created and this
     * fragment's view hierarchy instantiated.  It can be used to do final
     * initialization once these pieces are in place, such as retrieving
     * views or restoring state.  It is also useful for fragments that use
     * {@link #setRetainInstance(boolean)} to retain their instance,
     * as this callback tells the fragment when it is fully associated with
     * the new activity instance.  This is called after {@link #onCreateView}
     * and before {@link #onViewStateRestored(Bundle)}.
     *
     * @param savedInstanceState If the fragment is being re-created from
     * a previous saved state, this is the state.
     */
    @CallSuper
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        mCalled = true;
    }

    
Called when all saved state has been restored into the view hierarchy of the fragment. This can be used to do initialization based on saved state that you are letting the view hierarchy track itself, such as whether check box widgets are currently checked. This is called after onActivityCreated(Bundle) and before onStart(). 
Params:
  • savedInstanceState – If the fragment is being re-created from
a previous saved state, this is the state.
/**
     * Called when all saved state has been restored into the view hierarchy
     * of the fragment.  This can be used to do initialization based on saved
     * state that you are letting the view hierarchy track itself, such as
     * whether check box widgets are currently checked.  This is called
     * after {@link #onActivityCreated(Bundle)} and before
     * {@link #onStart()}.
     *
     * @param savedInstanceState If the fragment is being re-created from
     * a previous saved state, this is the state.
     */
    @CallSuper
    public void onViewStateRestored(Bundle savedInstanceState) {
        mCalled = true;
    }

    
Called when the Fragment is visible to the user. This is generally tied to Activity.onStart of the containing Activity's lifecycle. 
/**
     * Called when the Fragment is visible to the user.  This is generally
     * tied to {@link Activity#onStart() Activity.onStart} of the containing
     * Activity's lifecycle.
     */
    @CallSuper
    public void onStart() {
        mCalled = true;

        if (!mLoadersStarted) {
            mLoadersStarted = true;
            if (!mCheckedForLoaderManager) {
                mCheckedForLoaderManager = true;
                mLoaderManager = mHost.getLoaderManager(mWho, mLoadersStarted, false);
            } else if (mLoaderManager != null) {
                mLoaderManager.doStart();
            }
        }
    }

    
Called when the fragment is visible to the user and actively running. This is generally tied to Activity.onResume of the containing Activity's lifecycle. 
/**
     * Called when the fragment is visible to the user and actively running.
     * This is generally
     * tied to {@link Activity#onResume() Activity.onResume} of the containing
     * Activity's lifecycle.
     */
    @CallSuper
    public void onResume() {
        mCalled = true;
    }

    
Called to ask the fragment to save its current dynamic state, so it can later be reconstructed in a new instance of its process is restarted. If a new instance of the fragment later needs to be created, the data you place in the Bundle here will be available in the Bundle given to onCreate(Bundle), onCreateView(LayoutInflater, ViewGroup, Bundle), and onActivityCreated(Bundle). 
This corresponds to 
Activity.onSaveInstanceState(Bundle) and most of the discussion there applies here as well. Note however: this method may be called at any time before onDestroy().  There are many situations
where a fragment may be mostly torn down (such as when placed on the
back stack with no UI showing), but its state will not be saved until
its owning activity actually needs to save its state.

Params:
  • outState – Bundle in which to place your saved state.
/**
     * Called to ask the fragment to save its current dynamic state, so it
     * can later be reconstructed in a new instance of its process is
     * restarted.  If a new instance of the fragment later needs to be
     * created, the data you place in the Bundle here will be available
     * in the Bundle given to {@link #onCreate(Bundle)},
     * {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}, and
     * {@link #onActivityCreated(Bundle)}.
     *
     * <p>This corresponds to {@link Activity#onSaveInstanceState(Bundle)
     * Activity.onSaveInstanceState(Bundle)} and most of the discussion there
     * applies here as well.  Note however: <em>this method may be called
     * at any time before {@link #onDestroy()}</em>.  There are many situations
     * where a fragment may be mostly torn down (such as when placed on the
     * back stack with no UI showing), but its state will not be saved until
     * its owning activity actually needs to save its state.
     *
     * @param outState Bundle in which to place your saved state.
     */
    public void onSaveInstanceState(Bundle outState) {
    }

    
Called when the Fragment's activity changes from fullscreen mode to multi-window mode and visa-versa. This is generally tied to Activity.onMultiWindowModeChanged of the containing Activity. This method provides the same configuration that will be sent in the following onConfigurationChanged(Configuration) call after the activity enters this mode. 
Params:
  • isInMultiWindowMode – True if the activity is in multi-window mode.
  • newConfig – The new configuration of the activity with the state
                 {@param isInMultiWindowMode}.
/**
     * Called when the Fragment's activity changes from fullscreen mode to multi-window mode and
     * visa-versa. This is generally tied to {@link Activity#onMultiWindowModeChanged} of the
     * containing Activity. This method provides the same configuration that will be sent in the
     * following {@link #onConfigurationChanged(Configuration)} call after the activity enters this
     * mode.
     *
     * @param isInMultiWindowMode True if the activity is in multi-window mode.
     * @param newConfig The new configuration of the activity with the state
     *                  {@param isInMultiWindowMode}.
     */
    public void onMultiWindowModeChanged(boolean isInMultiWindowMode, Configuration newConfig) {
        onMultiWindowModeChanged(isInMultiWindowMode);
    }

    
Called when the Fragment's activity changes from fullscreen mode to multi-window mode and visa-versa. This is generally tied to Activity.onMultiWindowModeChanged of the containing Activity. 
Params:
  • isInMultiWindowMode – True if the activity is in multi-window mode.
Deprecated:Use onMultiWindowModeChanged(boolean, Configuration) instead.
/**
     * Called when the Fragment's activity changes from fullscreen mode to multi-window mode and
     * visa-versa. This is generally tied to {@link Activity#onMultiWindowModeChanged} of the
     * containing Activity.
     *
     * @param isInMultiWindowMode True if the activity is in multi-window mode.
     *
     * @deprecated Use {@link #onMultiWindowModeChanged(boolean, Configuration)} instead.
     */
    @Deprecated
    public void onMultiWindowModeChanged(boolean isInMultiWindowMode) {
    }

    
Called by the system when the activity changes to and from picture-in-picture mode. This is generally tied to Activity.onPictureInPictureModeChanged of the containing Activity. This method provides the same configuration that will be sent in the following onConfigurationChanged(Configuration) call after the activity enters this mode. 
Params:
  • isInPictureInPictureMode – True if the activity is in picture-in-picture mode.
  • newConfig – The new configuration of the activity with the state
                 {@param isInPictureInPictureMode}.
/**
     * Called by the system when the activity changes to and from picture-in-picture mode. This is
     * generally tied to {@link Activity#onPictureInPictureModeChanged} of the containing Activity.
     * This method provides the same configuration that will be sent in the following
     * {@link #onConfigurationChanged(Configuration)} call after the activity enters this mode.
     *
     * @param isInPictureInPictureMode True if the activity is in picture-in-picture mode.
     * @param newConfig The new configuration of the activity with the state
     *                  {@param isInPictureInPictureMode}.
     */
    public void onPictureInPictureModeChanged(boolean isInPictureInPictureMode,
            Configuration newConfig) {
        onPictureInPictureModeChanged(isInPictureInPictureMode);
    }

    
Called by the system when the activity changes to and from picture-in-picture mode. This is generally tied to Activity.onPictureInPictureModeChanged of the containing Activity. 
Params:
  • isInPictureInPictureMode – True if the activity is in picture-in-picture mode.
Deprecated:Use onPictureInPictureModeChanged(boolean, Configuration) instead.
/**
     * Called by the system when the activity changes to and from picture-in-picture mode. This is
     * generally tied to {@link Activity#onPictureInPictureModeChanged} of the containing Activity.
     *
     * @param isInPictureInPictureMode True if the activity is in picture-in-picture mode.
     *
     * @deprecated Use {@link #onPictureInPictureModeChanged(boolean, Configuration)} instead.
     */
    @Deprecated
    public void onPictureInPictureModeChanged(boolean isInPictureInPictureMode) {
    }

    @CallSuper
    public void onConfigurationChanged(Configuration newConfig) {
        mCalled = true;
    }

    
Called when the Fragment is no longer resumed. This is generally tied to Activity.onPause of the containing Activity's lifecycle. 
/**
     * Called when the Fragment is no longer resumed.  This is generally
     * tied to {@link Activity#onPause() Activity.onPause} of the containing
     * Activity's lifecycle.
     */
    @CallSuper
    public void onPause() {
        mCalled = true;
    }

    
Called when the Fragment is no longer started. This is generally tied to Activity.onStop of the containing Activity's lifecycle. 
/**
     * Called when the Fragment is no longer started.  This is generally
     * tied to {@link Activity#onStop() Activity.onStop} of the containing
     * Activity's lifecycle.
     */
    @CallSuper
    public void onStop() {
        mCalled = true;
    }

    @CallSuper
    public void onLowMemory() {
        mCalled = true;
    }

    @CallSuper
    public void onTrimMemory(int level) {
        mCalled = true;
    }

    
Called when the view previously created by onCreateView has been detached from the fragment. The next time the fragment needs to be displayed, a new view will be created. This is called after onStop() and before onDestroy(). It is called regardless of whether onCreateView returned a non-null view. Internally it is called after the view's state has been saved but before it has been removed from its parent. 
/**
     * Called when the view previously created by {@link #onCreateView} has
     * been detached from the fragment.  The next time the fragment needs
     * to be displayed, a new view will be created.  This is called
     * after {@link #onStop()} and before {@link #onDestroy()}.  It is called
     * <em>regardless</em> of whether {@link #onCreateView} returned a
     * non-null view.  Internally it is called after the view's state has
     * been saved but before it has been removed from its parent.
     */
    @CallSuper
    public void onDestroyView() {
        mCalled = true;
    }

    
Called when the fragment is no longer in use. This is called after onStop() and before onDetach(). 
/**
     * Called when the fragment is no longer in use.  This is called
     * after {@link #onStop()} and before {@link #onDetach()}.
     */
    @CallSuper
    public void onDestroy() {
        mCalled = true;
        //Log.v("foo", "onDestroy: mCheckedForLoaderManager=" + mCheckedForLoaderManager
        //        + " mLoaderManager=" + mLoaderManager);
        if (!mCheckedForLoaderManager) {
            mCheckedForLoaderManager = true;
            mLoaderManager = mHost.getLoaderManager(mWho, mLoadersStarted, false);
        }
        if (mLoaderManager != null) {
            mLoaderManager.doDestroy();
        }
    }

    
Called by the fragment manager once this fragment has been removed,
so that we don't have any left-over state if the application decides
to re-use the instance.  This only clears state that the framework
internally manages, not things the application sets.

/**
     * Called by the fragment manager once this fragment has been removed,
     * so that we don't have any left-over state if the application decides
     * to re-use the instance.  This only clears state that the framework
     * internally manages, not things the application sets.
     */
    void initState() {
        mIndex = -1;
        mWho = null;
        mAdded = false;
        mRemoving = false;
        mFromLayout = false;
        mInLayout = false;
        mRestored = false;
        mBackStackNesting = 0;
        mFragmentManager = null;
        mChildFragmentManager = null;
        mHost = null;
        mFragmentId = 0;
        mContainerId = 0;
        mTag = null;
        mHidden = false;
        mDetached = false;
        mRetaining = false;
        mLoaderManager = null;
        mLoadersStarted = false;
        mCheckedForLoaderManager = false;
    }

    
Called when the fragment is no longer attached to its activity. This is called after onDestroy(), except in the cases where the fragment instance is retained across Activity re-creation (see setRetainInstance(boolean)), in which case it is called after onStop(). 
/**
     * Called when the fragment is no longer attached to its activity.  This is called after
     * {@link #onDestroy()}, except in the cases where the fragment instance is retained across
     * Activity re-creation (see {@link #setRetainInstance(boolean)}), in which case it is called
     * after {@link #onStop()}.
     */
    @CallSuper
    public void onDetach() {
        mCalled = true;
    }

    
Initialize the contents of the Activity's standard options menu.  You
should place your menu items in to menu. For this method to be called, you must have first called setHasOptionsMenu. See Activity.onCreateOptionsMenu for more information. 
Params:
  • menu – The options menu in which you place your items.
See Also:
/**
     * Initialize the contents of the Activity's standard options menu.  You
     * should place your menu items in to <var>menu</var>.  For this method
     * to be called, you must have first called {@link #setHasOptionsMenu}.  See
     * {@link Activity#onCreateOptionsMenu(Menu) Activity.onCreateOptionsMenu}
     * for more information.
     *
     * @param menu The options menu in which you place your items.
     *
     * @see #setHasOptionsMenu
     * @see #onPrepareOptionsMenu
     * @see #onOptionsItemSelected
     */
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    }

    
Prepare the Screen's standard options menu to be displayed. This is called right before the menu is shown, every time it is shown. You can use this method to efficiently enable/disable items or otherwise dynamically modify the contents. See Activity.onPrepareOptionsMenu for more information. 
Params:
  • menu – The options menu as last shown or first initialized by
            onCreateOptionsMenu().
See Also:
/**
     * Prepare the Screen's standard options menu to be displayed.  This is
     * called right before the menu is shown, every time it is shown.  You can
     * use this method to efficiently enable/disable items or otherwise
     * dynamically modify the contents.  See
     * {@link Activity#onPrepareOptionsMenu(Menu) Activity.onPrepareOptionsMenu}
     * for more information.
     *
     * @param menu The options menu as last shown or first initialized by
     *             onCreateOptionsMenu().
     *
     * @see #setHasOptionsMenu
     * @see #onCreateOptionsMenu
     */
    public void onPrepareOptionsMenu(Menu menu) {
    }

    
Called when this fragment's option menu items are no longer being included in the overall options menu. Receiving this call means that the menu needed to be rebuilt, but this fragment's items were not included in the newly built menu (its onCreateOptionsMenu(Menu, MenuInflater) was not called). 
/**
     * Called when this fragment's option menu items are no longer being
     * included in the overall options menu.  Receiving this call means that
     * the menu needed to be rebuilt, but this fragment's items were not
     * included in the newly built menu (its {@link #onCreateOptionsMenu(Menu, MenuInflater)}
     * was not called).
     */
    public void onDestroyOptionsMenu() {
    }

    
This hook is called whenever an item in your options menu is selected.
The default implementation simply returns false to have the normal
processing happen (calling the item's Runnable or sending a message to
its Handler as appropriate).  You can use this method for any items
for which you would like to do processing without those other
facilities.

Derived classes should call through to the base class for it to
perform the default menu handling.

Params:
  • item – The menu item that was selected.
See Also:
Returns:boolean Return false to allow normal menu processing to
        proceed, true to consume it here.
/**
     * This hook is called whenever an item in your options menu is selected.
     * The default implementation simply returns false to have the normal
     * processing happen (calling the item's Runnable or sending a message to
     * its Handler as appropriate).  You can use this method for any items
     * for which you would like to do processing without those other
     * facilities.
     *
     * <p>Derived classes should call through to the base class for it to
     * perform the default menu handling.
     *
     * @param item The menu item that was selected.
     *
     * @return boolean Return false to allow normal menu processing to
     *         proceed, true to consume it here.
     *
     * @see #onCreateOptionsMenu
     */
    public boolean onOptionsItemSelected(MenuItem item) {
        return false;
    }

    
This hook is called whenever the options menu is being closed (either by the user canceling
the menu with the back/menu button, or when an item is selected).

Params:
  • menu – The options menu as last shown or first initialized by
            onCreateOptionsMenu().
/**
     * This hook is called whenever the options menu is being closed (either by the user canceling
     * the menu with the back/menu button, or when an item is selected).
     *
     * @param menu The options menu as last shown or first initialized by
     *             onCreateOptionsMenu().
     */
    public void onOptionsMenuClosed(Menu menu) {
    }

    
Called when a context menu for the view is about to be shown. Unlike onCreateOptionsMenu, this will be called every time the context menu is about to be shown and should be populated for the view (or item inside the view for AdapterView subclasses, this can be found in the menuInfo)). 
 Use onContextItemSelected(MenuItem) to know when an item has been selected. 
 The default implementation calls up to Activity.onCreateContextMenu, though you can not call this implementation if you don't want that behavior. 

It is not safe to hold onto the context menu after this method returns.
{@inheritDoc}

/**
     * Called when a context menu for the {@code view} is about to be shown.
     * Unlike {@link #onCreateOptionsMenu}, this will be called every
     * time the context menu is about to be shown and should be populated for
     * the view (or item inside the view for {@link AdapterView} subclasses,
     * this can be found in the {@code menuInfo})).
     * <p>
     * Use {@link #onContextItemSelected(android.view.MenuItem)} to know when an
     * item has been selected.
     * <p>
     * The default implementation calls up to
     * {@link Activity#onCreateContextMenu Activity.onCreateContextMenu}, though
     * you can not call this implementation if you don't want that behavior.
     * <p>
     * It is not safe to hold onto the context menu after this method returns.
     * {@inheritDoc}
     */
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
        getActivity().onCreateContextMenu(menu, v, menuInfo);
    }

    
Registers a context menu to be shown for the given view (multiple views can show the context menu). This method will set the OnCreateContextMenuListener on the view to this fragment, so onCreateContextMenu(ContextMenu, View, ContextMenuInfo) will be called when it is time to show the context menu. 
Params:
  • view – The view that should show a context menu.
See Also:
/**
     * Registers a context menu to be shown for the given view (multiple views
     * can show the context menu). This method will set the
     * {@link OnCreateContextMenuListener} on the view to this fragment, so
     * {@link #onCreateContextMenu(ContextMenu, View, ContextMenuInfo)} will be
     * called when it is time to show the context menu.
     *
     * @see #unregisterForContextMenu(View)
     * @param view The view that should show a context menu.
     */
    public void registerForContextMenu(View view) {
        view.setOnCreateContextMenuListener(this);
    }

    
Prevents a context menu to be shown for the given view. This method will remove the OnCreateContextMenuListener on the view. 
Params:
  • view – The view that should stop showing a context menu.
See Also:
/**
     * Prevents a context menu to be shown for the given view. This method will
     * remove the {@link OnCreateContextMenuListener} on the view.
     *
     * @see #registerForContextMenu(View)
     * @param view The view that should stop showing a context menu.
     */
    public void unregisterForContextMenu(View view) {
        view.setOnCreateContextMenuListener(null);
    }

    
This hook is called whenever an item in a context menu is selected. The
default implementation simply returns false to have the normal processing
happen (calling the item's Runnable or sending a message to its Handler
as appropriate). You can use this method for any items for which you
would like to do processing without those other facilities.

 Use MenuItem.getMenuInfo() to get extra information set by the View that added this menu item. 

Derived classes should call through to the base class for it to perform
the default menu handling.

Params:
  • item – The context menu item that was selected.
Returns:boolean Return false to allow normal context menu processing to
        proceed, true to consume it here.
/**
     * This hook is called whenever an item in a context menu is selected. The
     * default implementation simply returns false to have the normal processing
     * happen (calling the item's Runnable or sending a message to its Handler
     * as appropriate). You can use this method for any items for which you
     * would like to do processing without those other facilities.
     * <p>
     * Use {@link MenuItem#getMenuInfo()} to get extra information set by the
     * View that added this menu item.
     * <p>
     * Derived classes should call through to the base class for it to perform
     * the default menu handling.
     *
     * @param item The context menu item that was selected.
     * @return boolean Return false to allow normal context menu processing to
     *         proceed, true to consume it here.
     */
    public boolean onContextItemSelected(MenuItem item) {
        return false;
    }

    
When custom transitions are used with Fragments, the enter transition callback
is called when this Fragment is attached or detached when not popping the back stack.

Params:
  • callback – Used to manipulate the shared element transitions on this Fragment
                when added not as a pop from the back stack.
/**
     * When custom transitions are used with Fragments, the enter transition callback
     * is called when this Fragment is attached or detached when not popping the back stack.
     *
     * @param callback Used to manipulate the shared element transitions on this Fragment
     *                 when added not as a pop from the back stack.
     */
    public void setEnterSharedElementCallback(SharedElementCallback callback) {
        if (callback == null) {
            if (mAnimationInfo == null) {
                return; // already a null callback
            }
            callback = SharedElementCallback.NULL_CALLBACK;
        }
        ensureAnimationInfo().mEnterTransitionCallback = callback;
    }

    
When custom transitions are used with Fragments, the exit transition callback
is called when this Fragment is attached or detached when popping the back stack.

Params:
  • callback – Used to manipulate the shared element transitions on this Fragment
                when added as a pop from the back stack.
/**
     * When custom transitions are used with Fragments, the exit transition callback
     * is called when this Fragment is attached or detached when popping the back stack.
     *
     * @param callback Used to manipulate the shared element transitions on this Fragment
     *                 when added as a pop from the back stack.
     */
    public void setExitSharedElementCallback(SharedElementCallback callback) {
        if (callback == null) {
            if (mAnimationInfo == null) {
                return; // already a null callback
            }
            callback = SharedElementCallback.NULL_CALLBACK;
        }
        ensureAnimationInfo().mExitTransitionCallback = callback;
    }

    
Sets the Transition that will be used to move Views into the initial scene. The entering Views will be those that are regular Views or ViewGroups that have ViewGroup.isTransitionGroup return true. Typical Transitions will extend Visibility as entering is governed by changing visibility from View.INVISIBLE to View.VISIBLE. If transition is null,
entering Views will remain unaffected.

Params:
  • transition – The Transition to use to move Views into the initial Scene.
@attrref android.R.styleable#Fragment_fragmentEnterTransition
/**
     * Sets the Transition that will be used to move Views into the initial scene. The entering
     * Views will be those that are regular Views or ViewGroups that have
     * {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
     * {@link android.transition.Visibility} as entering is governed by changing visibility from
     * {@link View#INVISIBLE} to {@link View#VISIBLE}. If <code>transition</code> is null,
     * entering Views will remain unaffected.
     *
     * @param transition The Transition to use to move Views into the initial Scene.
     * @attr ref android.R.styleable#Fragment_fragmentEnterTransition
     */
    public void setEnterTransition(Transition transition) {
        if (shouldChangeTransition(transition, null)) {
            ensureAnimationInfo().mEnterTransition = transition;
        }
    }

    
Returns the Transition that will be used to move Views into the initial scene. The entering Views will be those that are regular Views or ViewGroups that have ViewGroup.isTransitionGroup return true. Typical Transitions will extend Visibility as entering is governed by changing visibility from View.INVISIBLE to View.VISIBLE. 
Returns:the Transition to use to move Views into the initial Scene.
@attrref android.R.styleable#Fragment_fragmentEnterTransition
/**
     * Returns the Transition that will be used to move Views into the initial scene. The entering
     * Views will be those that are regular Views or ViewGroups that have
     * {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
     * {@link android.transition.Visibility} as entering is governed by changing visibility from
     * {@link View#INVISIBLE} to {@link View#VISIBLE}.
     *
     * @return the Transition to use to move Views into the initial Scene.
     * @attr ref android.R.styleable#Fragment_fragmentEnterTransition
     */
    public Transition getEnterTransition() {
        if (mAnimationInfo == null) {
            return null;
        }
        return mAnimationInfo.mEnterTransition;
    }

    
Sets the Transition that will be used to move Views out of the scene when the Fragment is preparing to be removed, hidden, or detached because of popping the back stack. The exiting Views will be those that are regular Views or ViewGroups that have ViewGroup.isTransitionGroup return true. Typical Transitions will extend Visibility as entering is governed by changing visibility from View.VISIBLE to View.INVISIBLE. If transition is null, entering Views will remain unaffected. If nothing is set, the default will be to use the same value as set in setEnterTransition(Transition). 
Params:
  • transition – The Transition to use to move Views out of the Scene when the Fragment
                  is preparing to close.
@attrref android.R.styleable#Fragment_fragmentExitTransition
/**
     * Sets the Transition that will be used to move Views out of the scene when the Fragment is
     * preparing to be removed, hidden, or detached because of popping the back stack. The exiting
     * Views will be those that are regular Views or ViewGroups that have
     * {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
     * {@link android.transition.Visibility} as entering is governed by changing visibility from
     * {@link View#VISIBLE} to {@link View#INVISIBLE}. If <code>transition</code> is null,
     * entering Views will remain unaffected. If nothing is set, the default will be to
     * use the same value as set in {@link #setEnterTransition(android.transition.Transition)}.
     *
     * @param transition The Transition to use to move Views out of the Scene when the Fragment
     *                   is preparing to close.
     * @attr ref android.R.styleable#Fragment_fragmentExitTransition
     */
    public void setReturnTransition(Transition transition) {
        if (shouldChangeTransition(transition, USE_DEFAULT_TRANSITION)) {
            ensureAnimationInfo().mReturnTransition = transition;
        }
    }

    
Returns the Transition that will be used to move Views out of the scene when the Fragment is preparing to be removed, hidden, or detached because of popping the back stack. The exiting Views will be those that are regular Views or ViewGroups that have ViewGroup.isTransitionGroup return true. Typical Transitions will extend Visibility as entering is governed by changing visibility from View.VISIBLE to View.INVISIBLE. If transition is null,
entering Views will remain unaffected.

Returns:the Transition to use to move Views out of the Scene when the Fragment
        is preparing to close.
@attrref android.R.styleable#Fragment_fragmentExitTransition
/**
     * Returns the Transition that will be used to move Views out of the scene when the Fragment is
     * preparing to be removed, hidden, or detached because of popping the back stack. The exiting
     * Views will be those that are regular Views or ViewGroups that have
     * {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
     * {@link android.transition.Visibility} as entering is governed by changing visibility from
     * {@link View#VISIBLE} to {@link View#INVISIBLE}. If <code>transition</code> is null,
     * entering Views will remain unaffected.
     *
     * @return the Transition to use to move Views out of the Scene when the Fragment
     *         is preparing to close.
     * @attr ref android.R.styleable#Fragment_fragmentExitTransition
     */
    public Transition getReturnTransition() {
        if (mAnimationInfo == null) {
            return null;
        }
        return mAnimationInfo.mReturnTransition == USE_DEFAULT_TRANSITION ? getEnterTransition()
                : mAnimationInfo.mReturnTransition;
    }

    
Sets the Transition that will be used to move Views out of the scene when the fragment is removed, hidden, or detached when not popping the back stack. The exiting Views will be those that are regular Views or ViewGroups that have ViewGroup.isTransitionGroup return true. Typical Transitions will extend Visibility as exiting is governed by changing visibility from View.VISIBLE to View.INVISIBLE. If transition is null, the views will remain unaffected. 
Params:
  • transition – The Transition to use to move Views out of the Scene when the Fragment
                  is being closed not due to popping the back stack.
@attrref android.R.styleable#Fragment_fragmentExitTransition
/**
     * Sets the Transition that will be used to move Views out of the scene when the
     * fragment is removed, hidden, or detached when not popping the back stack.
     * The exiting Views will be those that are regular Views or ViewGroups that
     * have {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
     * {@link android.transition.Visibility} as exiting is governed by changing visibility
     * from {@link View#VISIBLE} to {@link View#INVISIBLE}. If transition is null, the views will
     * remain unaffected.
     *
     * @param transition The Transition to use to move Views out of the Scene when the Fragment
     *                   is being closed not due to popping the back stack.
     * @attr ref android.R.styleable#Fragment_fragmentExitTransition
     */
    public void setExitTransition(Transition transition) {
        if (shouldChangeTransition(transition, null)) {
            ensureAnimationInfo().mExitTransition = transition;
        }
    }

    
Returns the Transition that will be used to move Views out of the scene when the fragment is removed, hidden, or detached when not popping the back stack. The exiting Views will be those that are regular Views or ViewGroups that have ViewGroup.isTransitionGroup return true. Typical Transitions will extend Visibility as exiting is governed by changing visibility from View.VISIBLE to View.INVISIBLE. If transition is null, the views will remain unaffected. 
Returns:the Transition to use to move Views out of the Scene when the Fragment
        is being closed not due to popping the back stack.
@attrref android.R.styleable#Fragment_fragmentExitTransition
/**
     * Returns the Transition that will be used to move Views out of the scene when the
     * fragment is removed, hidden, or detached when not popping the back stack.
     * The exiting Views will be those that are regular Views or ViewGroups that
     * have {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
     * {@link android.transition.Visibility} as exiting is governed by changing visibility
     * from {@link View#VISIBLE} to {@link View#INVISIBLE}. If transition is null, the views will
     * remain unaffected.
     *
     * @return the Transition to use to move Views out of the Scene when the Fragment
     *         is being closed not due to popping the back stack.
     * @attr ref android.R.styleable#Fragment_fragmentExitTransition
     */
    public Transition getExitTransition() {
        if (mAnimationInfo == null) {
            return null;
        }
        return mAnimationInfo.mExitTransition;
    }

    
Sets the Transition that will be used to move Views in to the scene when returning due to popping a back stack. The entering Views will be those that are regular Views or ViewGroups that have ViewGroup.isTransitionGroup return true. Typical Transitions will extend Visibility as exiting is governed by changing visibility from View.VISIBLE to View.INVISIBLE. If transition is null, the views will remain unaffected. If nothing is set, the default will be to use the same transition as setExitTransition(Transition). 
Params:
  • transition – The Transition to use to move Views into the scene when reentering from a
                  previously-started Activity.
@attrref android.R.styleable#Fragment_fragmentReenterTransition
/**
     * Sets the Transition that will be used to move Views in to the scene when returning due
     * to popping a back stack. The entering Views will be those that are regular Views
     * or ViewGroups that have {@link ViewGroup#isTransitionGroup} return true. Typical Transitions
     * will extend {@link android.transition.Visibility} as exiting is governed by changing
     * visibility from {@link View#VISIBLE} to {@link View#INVISIBLE}. If transition is null,
     * the views will remain unaffected. If nothing is set, the default will be to use the same
     * transition as {@link #setExitTransition(android.transition.Transition)}.
     *
     * @param transition The Transition to use to move Views into the scene when reentering from a
     *                   previously-started Activity.
     * @attr ref android.R.styleable#Fragment_fragmentReenterTransition
     */
    public void setReenterTransition(Transition transition) {
        if (shouldChangeTransition(transition, USE_DEFAULT_TRANSITION)) {
            ensureAnimationInfo().mReenterTransition = transition;
        }
    }

    
Returns the Transition that will be used to move Views in to the scene when returning due to popping a back stack. The entering Views will be those that are regular Views or ViewGroups that have ViewGroup.isTransitionGroup return true. Typical Transitions will extend Visibility as exiting is governed by changing visibility from View.VISIBLE to View.INVISIBLE. If transition is null, the views will remain unaffected. If nothing is set, the default will be to use the same transition as setExitTransition(Transition). 
Returns:the Transition to use to move Views into the scene when reentering from a
                  previously-started Activity.
@attrref android.R.styleable#Fragment_fragmentReenterTransition
/**
     * Returns the Transition that will be used to move Views in to the scene when returning due
     * to popping a back stack. The entering Views will be those that are regular Views
     * or ViewGroups that have {@link ViewGroup#isTransitionGroup} return true. Typical Transitions
     * will extend {@link android.transition.Visibility} as exiting is governed by changing
     * visibility from {@link View#VISIBLE} to {@link View#INVISIBLE}. If transition is null,
     * the views will remain unaffected. If nothing is set, the default will be to use the same
     * transition as {@link #setExitTransition(android.transition.Transition)}.
     *
     * @return the Transition to use to move Views into the scene when reentering from a
     *                   previously-started Activity.
     * @attr ref android.R.styleable#Fragment_fragmentReenterTransition
     */
    public Transition getReenterTransition() {
        if (mAnimationInfo == null) {
            return null;
        }
        return mAnimationInfo.mReenterTransition == USE_DEFAULT_TRANSITION ? getExitTransition()
                : mAnimationInfo.mReenterTransition;
    }

    
Sets the Transition that will be used for shared elements transferred into the content Scene. Typical Transitions will affect size and location, such as ChangeBounds. A null value will cause transferred shared elements to blink to the final position. 
Params:
  • transition – The Transition to use for shared elements transferred into the content
                  Scene.
@attrref android.R.styleable#Fragment_fragmentSharedElementEnterTransition
/**
     * Sets the Transition that will be used for shared elements transferred into the content
     * Scene. Typical Transitions will affect size and location, such as
     * {@link android.transition.ChangeBounds}. A null
     * value will cause transferred shared elements to blink to the final position.
     *
     * @param transition The Transition to use for shared elements transferred into the content
     *                   Scene.
     * @attr ref android.R.styleable#Fragment_fragmentSharedElementEnterTransition
     */
    public void setSharedElementEnterTransition(Transition transition) {
        if (shouldChangeTransition(transition, null)) {
            ensureAnimationInfo().mSharedElementEnterTransition = transition;
        }
    }

    
Returns the Transition that will be used for shared elements transferred into the content Scene. Typical Transitions will affect size and location, such as ChangeBounds. A null value will cause transferred shared elements to blink to the final position. 
Returns:The Transition to use for shared elements transferred into the content
                  Scene.
@attrref android.R.styleable#Fragment_fragmentSharedElementEnterTransition
/**
     * Returns the Transition that will be used for shared elements transferred into the content
     * Scene. Typical Transitions will affect size and location, such as
     * {@link android.transition.ChangeBounds}. A null
     * value will cause transferred shared elements to blink to the final position.
     *
     * @return The Transition to use for shared elements transferred into the content
     *                   Scene.
     * @attr ref android.R.styleable#Fragment_fragmentSharedElementEnterTransition
     */
    public Transition getSharedElementEnterTransition() {
        if (mAnimationInfo == null) {
            return null;
        }
        return mAnimationInfo.mSharedElementEnterTransition;
    }

    
Sets the Transition that will be used for shared elements transferred back during a pop of the back stack. This Transition acts in the leaving Fragment. Typical Transitions will affect size and location, such as ChangeBounds. A null value will cause transferred shared elements to blink to the final position. If no value is set, the default will be to use the same value as setSharedElementEnterTransition(Transition). 
Params:
  • transition – The Transition to use for shared elements transferred out of the content
                  Scene.
@attrref android.R.styleable#Fragment_fragmentSharedElementReturnTransition
/**
     * Sets the Transition that will be used for shared elements transferred back during a
     * pop of the back stack. This Transition acts in the leaving Fragment.
     * Typical Transitions will affect size and location, such as
     * {@link android.transition.ChangeBounds}. A null
     * value will cause transferred shared elements to blink to the final position.
     * If no value is set, the default will be to use the same value as
     * {@link #setSharedElementEnterTransition(android.transition.Transition)}.
     *
     * @param transition The Transition to use for shared elements transferred out of the content
     *                   Scene.
     * @attr ref android.R.styleable#Fragment_fragmentSharedElementReturnTransition
     */
    public void setSharedElementReturnTransition(Transition transition) {
        if (shouldChangeTransition(transition, USE_DEFAULT_TRANSITION)) {
            ensureAnimationInfo().mSharedElementReturnTransition = transition;
        }
    }

    
Return the Transition that will be used for shared elements transferred back during a pop of the back stack. This Transition acts in the leaving Fragment. Typical Transitions will affect size and location, such as ChangeBounds. A null value will cause transferred shared elements to blink to the final position. If no value is set, the default will be to use the same value as setSharedElementEnterTransition(Transition). 
Returns:The Transition to use for shared elements transferred out of the content
                  Scene.
@attrref android.R.styleable#Fragment_fragmentSharedElementReturnTransition
/**
     * Return the Transition that will be used for shared elements transferred back during a
     * pop of the back stack. This Transition acts in the leaving Fragment.
     * Typical Transitions will affect size and location, such as
     * {@link android.transition.ChangeBounds}. A null
     * value will cause transferred shared elements to blink to the final position.
     * If no value is set, the default will be to use the same value as
     * {@link #setSharedElementEnterTransition(android.transition.Transition)}.
     *
     * @return The Transition to use for shared elements transferred out of the content
     *                   Scene.
     * @attr ref android.R.styleable#Fragment_fragmentSharedElementReturnTransition
     */
    public Transition getSharedElementReturnTransition() {
        if (mAnimationInfo == null) {
            return null;
        }
        return mAnimationInfo.mSharedElementReturnTransition == USE_DEFAULT_TRANSITION
                ? getSharedElementEnterTransition()
                : mAnimationInfo.mSharedElementReturnTransition;
    }

    
Sets whether the exit transition and enter transition overlap or not.
When true, the enter transition will start as soon as possible. When false, the
enter transition will wait until the exit transition completes before starting.

Params:
  • allow – true to start the enter transition when possible or false to
             wait until the exiting transition completes.
@attrref android.R.styleable#Fragment_fragmentAllowEnterTransitionOverlap
/**
     * Sets whether the exit transition and enter transition overlap or not.
     * When true, the enter transition will start as soon as possible. When false, the
     * enter transition will wait until the exit transition completes before starting.
     *
     * @param allow true to start the enter transition when possible or false to
     *              wait until the exiting transition completes.
     * @attr ref android.R.styleable#Fragment_fragmentAllowEnterTransitionOverlap
     */
    public void setAllowEnterTransitionOverlap(boolean allow) {
        ensureAnimationInfo().mAllowEnterTransitionOverlap = allow;
    }

    
Returns whether the exit transition and enter transition overlap or not.
When true, the enter transition will start as soon as possible. When false, the
enter transition will wait until the exit transition completes before starting.

Returns:true when the enter transition should start as soon as possible or false to
when it should wait until the exiting transition completes.
@attrref android.R.styleable#Fragment_fragmentAllowEnterTransitionOverlap
/**
     * Returns whether the exit transition and enter transition overlap or not.
     * When true, the enter transition will start as soon as possible. When false, the
     * enter transition will wait until the exit transition completes before starting.
     *
     * @return true when the enter transition should start as soon as possible or false to
     * when it should wait until the exiting transition completes.
     * @attr ref android.R.styleable#Fragment_fragmentAllowEnterTransitionOverlap
     */
    public boolean getAllowEnterTransitionOverlap() {
        return (mAnimationInfo == null || mAnimationInfo.mAllowEnterTransitionOverlap == null)
                ? true : mAnimationInfo.mAllowEnterTransitionOverlap;
    }

    
Sets whether the return transition and reenter transition overlap or not.
When true, the reenter transition will start as soon as possible. When false, the
reenter transition will wait until the return transition completes before starting.

Params:
  • allow – true to start the reenter transition when possible or false to wait until the
             return transition completes.
@attrref android.R.styleable#Fragment_fragmentAllowReturnTransitionOverlap
/**
     * Sets whether the return transition and reenter transition overlap or not.
     * When true, the reenter transition will start as soon as possible. When false, the
     * reenter transition will wait until the return transition completes before starting.
     *
     * @param allow true to start the reenter transition when possible or false to wait until the
     *              return transition completes.
     * @attr ref android.R.styleable#Fragment_fragmentAllowReturnTransitionOverlap
     */
    public void setAllowReturnTransitionOverlap(boolean allow) {
        ensureAnimationInfo().mAllowReturnTransitionOverlap = allow;
    }

    
Returns whether the return transition and reenter transition overlap or not.
When true, the reenter transition will start as soon as possible. When false, the
reenter transition will wait until the return transition completes before starting.

Returns:true to start the reenter transition when possible or false to wait until the
        return transition completes.
@attrref android.R.styleable#Fragment_fragmentAllowReturnTransitionOverlap
/**
     * Returns whether the return transition and reenter transition overlap or not.
     * When true, the reenter transition will start as soon as possible. When false, the
     * reenter transition will wait until the return transition completes before starting.
     *
     * @return true to start the reenter transition when possible or false to wait until the
     *         return transition completes.
     * @attr ref android.R.styleable#Fragment_fragmentAllowReturnTransitionOverlap
     */
    public boolean getAllowReturnTransitionOverlap() {
        return (mAnimationInfo == null || mAnimationInfo.mAllowReturnTransitionOverlap == null)
                ? true : mAnimationInfo.mAllowReturnTransitionOverlap;
    }

    
Postpone the entering Fragment transition until startPostponedEnterTransition() or FragmentManager.executePendingTransactions() has been called. 
 This method gives the Fragment the ability to delay Fragment animations until all data is loaded. Until then, the added, shown, and attached Fragments will be INVISIBLE and removed, hidden, and detached Fragments won't be have their Views removed. The transaction runs when all postponed added Fragments in the transaction have called startPostponedEnterTransition(). 
 This method should be called before being added to the FragmentTransaction or in onCreate(Bundle), onAttach(Context), or onCreateView(LayoutInflater, ViewGroup, Bundle)}. startPostponedEnterTransition() must be called to allow the Fragment to start the transitions. 

When a FragmentTransaction is started that may affect a postponed FragmentTransaction,
based on which containers are in their operations, the postponed FragmentTransaction
will have its start triggered. The early triggering may result in faulty or nonexistent
animations in the postponed transaction. FragmentTransactions that operate only on
independent containers will not interfere with each other's postponement.


Calling postponeEnterTransition on Fragments with a null View will not postpone the
transition. Likewise, postponement only works if FragmentTransaction optimizations are
enabled.

See Also:
/**
     * Postpone the entering Fragment transition until {@link #startPostponedEnterTransition()}
     * or {@link FragmentManager#executePendingTransactions()} has been called.
     * <p>
     * This method gives the Fragment the ability to delay Fragment animations
     * until all data is loaded. Until then, the added, shown, and
     * attached Fragments will be INVISIBLE and removed, hidden, and detached Fragments won't
     * be have their Views removed. The transaction runs when all postponed added Fragments in the
     * transaction have called {@link #startPostponedEnterTransition()}.
     * <p>
     * This method should be called before being added to the FragmentTransaction or
     * in {@link #onCreate(Bundle)}, {@link #onAttach(Context)}, or
     * {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}}.
     * {@link #startPostponedEnterTransition()} must be called to allow the Fragment to
     * start the transitions.
     * <p>
     * When a FragmentTransaction is started that may affect a postponed FragmentTransaction,
     * based on which containers are in their operations, the postponed FragmentTransaction
     * will have its start triggered. The early triggering may result in faulty or nonexistent
     * animations in the postponed transaction. FragmentTransactions that operate only on
     * independent containers will not interfere with each other's postponement.
     * <p>
     * Calling postponeEnterTransition on Fragments with a null View will not postpone the
     * transition. Likewise, postponement only works if FragmentTransaction optimizations are
     * enabled.
     *
     * @see Activity#postponeEnterTransition()
     * @see FragmentTransaction#setReorderingAllowed(boolean)
     */
    public void postponeEnterTransition() {
        ensureAnimationInfo().mEnterTransitionPostponed = true;
    }

    
Begin postponed transitions after postponeEnterTransition() was called. If postponeEnterTransition() was called, you must call startPostponedEnterTransition() or FragmentManager.executePendingTransactions() to complete the FragmentTransaction. If postponement was interrupted with FragmentManager.executePendingTransactions(), before startPostponedEnterTransition(), animations may not run or may execute improperly. 
See Also:
/**
     * Begin postponed transitions after {@link #postponeEnterTransition()} was called.
     * If postponeEnterTransition() was called, you must call startPostponedEnterTransition()
     * or {@link FragmentManager#executePendingTransactions()} to complete the FragmentTransaction.
     * If postponement was interrupted with {@link FragmentManager#executePendingTransactions()},
     * before {@code startPostponedEnterTransition()}, animations may not run or may execute
     * improperly.
     *
     * @see Activity#startPostponedEnterTransition()
     */
    public void startPostponedEnterTransition() {
        if (mFragmentManager == null || mFragmentManager.mHost == null) {
                ensureAnimationInfo().mEnterTransitionPostponed = false;
        } else if (Looper.myLooper() != mFragmentManager.mHost.getHandler().getLooper()) {
            mFragmentManager.mHost.getHandler().
                    postAtFrontOfQueue(this::callStartTransitionListener);
        } else {
            callStartTransitionListener();
        }
    }

    
Calls the start transition listener. This must be called on the UI thread.

/**
     * Calls the start transition listener. This must be called on the UI thread.
     */
    private void callStartTransitionListener() {
        final OnStartEnterTransitionListener listener;
        if (mAnimationInfo == null) {
            listener = null;
        } else {
            mAnimationInfo.mEnterTransitionPostponed = false;
            listener = mAnimationInfo.mStartEnterTransitionListener;
            mAnimationInfo.mStartEnterTransitionListener = null;
        }
        if (listener != null) {
            listener.onStartEnterTransition();
        }
    }

    
Returns true if mAnimationInfo is not null or the transition differs from the default value.
This is broken out to ensure mAnimationInfo is properly locked when checking.

/**
     * Returns true if mAnimationInfo is not null or the transition differs from the default value.
     * This is broken out to ensure mAnimationInfo is properly locked when checking.
     */
    private boolean shouldChangeTransition(Transition transition, Transition defaultValue) {
        if (transition == defaultValue) {
            return mAnimationInfo != null;
        }
        return true;
    }

    
Print the Fragments's state into the given stream.

Params:
  • prefix – Text to print at the front of each line.
  • fd – The raw file descriptor that the dump is being sent to.
  • writer – The PrintWriter to which you should dump your state.  This will be
closed for you after you return.
  • args – additional arguments to the dump request.
/**
     * Print the Fragments's state into the given stream.
     *
     * @param prefix Text to print at the front of each line.
     * @param fd The raw file descriptor that the dump is being sent to.
     * @param writer The PrintWriter to which you should dump your state.  This will be
     * closed for you after you return.
     * @param args additional arguments to the dump request.
     */
    public void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) {
        writer.print(prefix); writer.print("mFragmentId=#");
        writer.print(Integer.toHexString(mFragmentId));
        writer.print(" mContainerId=#");
        writer.print(Integer.toHexString(mContainerId));
        writer.print(" mTag="); writer.println(mTag);
        writer.print(prefix); writer.print("mState="); writer.print(mState);
        writer.print(" mIndex="); writer.print(mIndex);
        writer.print(" mWho="); writer.print(mWho);
        writer.print(" mBackStackNesting="); writer.println(mBackStackNesting);
        writer.print(prefix); writer.print("mAdded="); writer.print(mAdded);
        writer.print(" mRemoving="); writer.print(mRemoving);
        writer.print(" mFromLayout="); writer.print(mFromLayout);
        writer.print(" mInLayout="); writer.println(mInLayout);
        writer.print(prefix); writer.print("mHidden="); writer.print(mHidden);
        writer.print(" mDetached="); writer.print(mDetached);
        writer.print(" mMenuVisible="); writer.print(mMenuVisible);
        writer.print(" mHasMenu="); writer.println(mHasMenu);
        writer.print(prefix); writer.print("mRetainInstance="); writer.print(mRetainInstance);
        writer.print(" mRetaining="); writer.print(mRetaining);
        writer.print(" mUserVisibleHint="); writer.println(mUserVisibleHint);
        if (mFragmentManager != null) {
            writer.print(prefix); writer.print("mFragmentManager=");
            writer.println(mFragmentManager);
        }
        if (mHost != null) {
            writer.print(prefix); writer.print("mHost=");
            writer.println(mHost);
        }
        if (mParentFragment != null) {
            writer.print(prefix); writer.print("mParentFragment=");
            writer.println(mParentFragment);
        }
        if (mArguments != null) {
            writer.print(prefix); writer.print("mArguments="); writer.println(mArguments);
        }
        if (mSavedFragmentState != null) {
            writer.print(prefix); writer.print("mSavedFragmentState=");
            writer.println(mSavedFragmentState);
        }
        if (mSavedViewState != null) {
            writer.print(prefix); writer.print("mSavedViewState=");
            writer.println(mSavedViewState);
        }
        if (mTarget != null) {
            writer.print(prefix); writer.print("mTarget="); writer.print(mTarget);
            writer.print(" mTargetRequestCode=");
            writer.println(mTargetRequestCode);
        }
        if (getNextAnim() != 0) {
            writer.print(prefix); writer.print("mNextAnim="); writer.println(getNextAnim());
        }
        if (mContainer != null) {
            writer.print(prefix); writer.print("mContainer="); writer.println(mContainer);
        }
        if (mView != null) {
            writer.print(prefix); writer.print("mView="); writer.println(mView);
        }
        if (getAnimatingAway() != null) {
            writer.print(prefix); writer.print("mAnimatingAway=");
            writer.println(getAnimatingAway());
            writer.print(prefix); writer.print("mStateAfterAnimating=");
            writer.println(getStateAfterAnimating());
        }
        if (mLoaderManager != null) {
            writer.print(prefix); writer.println("Loader Manager:");
            mLoaderManager.dump(prefix + "  ", fd, writer, args);
        }
        if (mChildFragmentManager != null) {
            writer.print(prefix); writer.println("Child " + mChildFragmentManager + ":");
            mChildFragmentManager.dump(prefix + "  ", fd, writer, args);
        }
    }

    Fragment findFragmentByWho(String who) {
        if (who.equals(mWho)) {
            return this;
        }
        if (mChildFragmentManager != null) {
            return mChildFragmentManager.findFragmentByWho(who);
        }
        return null;
    }

    void instantiateChildFragmentManager() {
        mChildFragmentManager = new FragmentManagerImpl();
        mChildFragmentManager.attachController(mHost, new FragmentContainer() {
            @Override
            @Nullable
            public <T extends View> T onFindViewById(int id) {
                if (mView == null) {
                    throw new IllegalStateException("Fragment does not have a view");
                }
                return mView.findViewById(id);
            }

            @Override
            public boolean onHasView() {
                return (mView != null);
            }
        }, this);
    }

    void performCreate(Bundle savedInstanceState) {
        if (mChildFragmentManager != null) {
            mChildFragmentManager.noteStateNotSaved();
        }
        mState = CREATED;
        mCalled = false;
        onCreate(savedInstanceState);
        mIsCreated = true;
        if (!mCalled) {
            throw new SuperNotCalledException("Fragment " + this
                    + " did not call through to super.onCreate()");
        }
        final Context context = getContext();
        final int version = context != null ? context.getApplicationInfo().targetSdkVersion : 0;
        if (version < Build.VERSION_CODES.N) {
            restoreChildFragmentState(savedInstanceState, false);
        }
    }

    View performCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        if (mChildFragmentManager != null) {
            mChildFragmentManager.noteStateNotSaved();
        }
        mPerformedCreateView = true;
        return onCreateView(inflater, container, savedInstanceState);
    }

    void performActivityCreated(Bundle savedInstanceState) {
        if (mChildFragmentManager != null) {
            mChildFragmentManager.noteStateNotSaved();
        }
        mState = ACTIVITY_CREATED;
        mCalled = false;
        onActivityCreated(savedInstanceState);
        if (!mCalled) {
            throw new SuperNotCalledException("Fragment " + this
                    + " did not call through to super.onActivityCreated()");
        }
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchActivityCreated();
        }
    }

    void performStart() {
        if (mChildFragmentManager != null) {
            mChildFragmentManager.noteStateNotSaved();
            mChildFragmentManager.execPendingActions();
        }
        mState = STARTED;
        mCalled = false;
        onStart();
        if (!mCalled) {
            throw new SuperNotCalledException("Fragment " + this
                    + " did not call through to super.onStart()");
        }
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchStart();
        }
        if (mLoaderManager != null) {
            mLoaderManager.doReportStart();
        }
    }

    void performResume() {
        if (mChildFragmentManager != null) {
            mChildFragmentManager.noteStateNotSaved();
            mChildFragmentManager.execPendingActions();
        }
        mState = RESUMED;
        mCalled = false;
        onResume();
        if (!mCalled) {
            throw new SuperNotCalledException("Fragment " + this
                    + " did not call through to super.onResume()");
        }
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchResume();
            mChildFragmentManager.execPendingActions();
        }
    }

    void noteStateNotSaved() {
        if (mChildFragmentManager != null) {
            mChildFragmentManager.noteStateNotSaved();
        }
    }

    @Deprecated
    void performMultiWindowModeChanged(boolean isInMultiWindowMode) {
        onMultiWindowModeChanged(isInMultiWindowMode);
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchMultiWindowModeChanged(isInMultiWindowMode);
        }
    }

    void performMultiWindowModeChanged(boolean isInMultiWindowMode, Configuration newConfig) {
        onMultiWindowModeChanged(isInMultiWindowMode, newConfig);
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchMultiWindowModeChanged(isInMultiWindowMode, newConfig);
        }
    }

    @Deprecated
    void performPictureInPictureModeChanged(boolean isInPictureInPictureMode) {
        onPictureInPictureModeChanged(isInPictureInPictureMode);
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchPictureInPictureModeChanged(isInPictureInPictureMode);
        }
    }

    void performPictureInPictureModeChanged(boolean isInPictureInPictureMode,
            Configuration newConfig) {
        onPictureInPictureModeChanged(isInPictureInPictureMode, newConfig);
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchPictureInPictureModeChanged(isInPictureInPictureMode,
                    newConfig);
        }
    }

    void performConfigurationChanged(Configuration newConfig) {
        onConfigurationChanged(newConfig);
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchConfigurationChanged(newConfig);
        }
    }

    void performLowMemory() {
        onLowMemory();
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchLowMemory();
        }
    }

    void performTrimMemory(int level) {
        onTrimMemory(level);
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchTrimMemory(level);
        }
    }

    boolean performCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        boolean show = false;
        if (!mHidden) {
            if (mHasMenu && mMenuVisible) {
                show = true;
                onCreateOptionsMenu(menu, inflater);
            }
            if (mChildFragmentManager != null) {
                show |= mChildFragmentManager.dispatchCreateOptionsMenu(menu, inflater);
            }
        }
        return show;
    }

    boolean performPrepareOptionsMenu(Menu menu) {
        boolean show = false;
        if (!mHidden) {
            if (mHasMenu && mMenuVisible) {
                show = true;
                onPrepareOptionsMenu(menu);
            }
            if (mChildFragmentManager != null) {
                show |= mChildFragmentManager.dispatchPrepareOptionsMenu(menu);
            }
        }
        return show;
    }

    boolean performOptionsItemSelected(MenuItem item) {
        if (!mHidden) {
            if (mHasMenu && mMenuVisible) {
                if (onOptionsItemSelected(item)) {
                    return true;
                }
            }
            if (mChildFragmentManager != null) {
                if (mChildFragmentManager.dispatchOptionsItemSelected(item)) {
                    return true;
                }
            }
        }
        return false;
    }

    boolean performContextItemSelected(MenuItem item) {
        if (!mHidden) {
            if (onContextItemSelected(item)) {
                return true;
            }
            if (mChildFragmentManager != null) {
                if (mChildFragmentManager.dispatchContextItemSelected(item)) {
                    return true;
                }
            }
        }
        return false;
    }

    void performOptionsMenuClosed(Menu menu) {
        if (!mHidden) {
            if (mHasMenu && mMenuVisible) {
                onOptionsMenuClosed(menu);
            }
            if (mChildFragmentManager != null) {
                mChildFragmentManager.dispatchOptionsMenuClosed(menu);
            }
        }
    }

    void performSaveInstanceState(Bundle outState) {
        onSaveInstanceState(outState);
        if (mChildFragmentManager != null) {
            Parcelable p = mChildFragmentManager.saveAllState();
            if (p != null) {
                outState.putParcelable(Activity.FRAGMENTS_TAG, p);
            }
        }
    }

    void performPause() {
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchPause();
        }
        mState = STARTED;
        mCalled = false;
        onPause();
        if (!mCalled) {
            throw new SuperNotCalledException("Fragment " + this
                    + " did not call through to super.onPause()");
        }
    }

    void performStop() {
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchStop();
        }
        mState = STOPPED;
        mCalled = false;
        onStop();
        if (!mCalled) {
            throw new SuperNotCalledException("Fragment " + this
                    + " did not call through to super.onStop()");
        }

        if (mLoadersStarted) {
            mLoadersStarted = false;
            if (!mCheckedForLoaderManager) {
                mCheckedForLoaderManager = true;
                mLoaderManager = mHost.getLoaderManager(mWho, mLoadersStarted, false);
            }
            if (mLoaderManager != null) {
                if (mHost.getRetainLoaders()) {
                    mLoaderManager.doRetain();
                } else {
                    mLoaderManager.doStop();
                }
            }
        }
    }

    void performDestroyView() {
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchDestroyView();
        }
        mState = CREATED;
        mCalled = false;
        onDestroyView();
        if (!mCalled) {
            throw new SuperNotCalledException("Fragment " + this
                    + " did not call through to super.onDestroyView()");
        }
        if (mLoaderManager != null) {
            mLoaderManager.doReportNextStart();
        }
        mPerformedCreateView = false;
    }

    void performDestroy() {
        if (mChildFragmentManager != null) {
            mChildFragmentManager.dispatchDestroy();
        }
        mState = INITIALIZING;
        mCalled = false;
        mIsCreated = false;
        onDestroy();
        if (!mCalled) {
            throw new SuperNotCalledException("Fragment " + this
                    + " did not call through to super.onDestroy()");
        }
        mChildFragmentManager = null;
    }

    void performDetach() {
        mCalled = false;
        onDetach();
        mLayoutInflater = null;
        if (!mCalled) {
            throw new SuperNotCalledException("Fragment " + this
                    + " did not call through to super.onDetach()");
        }

        // Destroy the child FragmentManager if we still have it here.
        // We won't unless we're retaining our instance and if we do,
        // our child FragmentManager instance state will have already been saved.
        if (mChildFragmentManager != null) {
            if (!mRetaining) {
                throw new IllegalStateException("Child FragmentManager of " + this + " was not "
                        + " destroyed and this fragment is not retaining instance");
            }
            mChildFragmentManager.dispatchDestroy();
            mChildFragmentManager = null;
        }
    }

    void setOnStartEnterTransitionListener(OnStartEnterTransitionListener listener) {
        ensureAnimationInfo();
        if (listener == mAnimationInfo.mStartEnterTransitionListener) {
            return;
        }
        if (listener != null && mAnimationInfo.mStartEnterTransitionListener != null) {
            throw new IllegalStateException("Trying to set a replacement " +
                    "startPostponedEnterTransition on " + this);
        }
        if (mAnimationInfo.mEnterTransitionPostponed) {
            mAnimationInfo.mStartEnterTransitionListener = listener;
        }
        if (listener != null) {
            listener.startListening();
        }
    }

    private static Transition loadTransition(Context context, TypedArray typedArray,
            Transition currentValue, Transition defaultValue, int id) {
        if (currentValue != defaultValue) {
            return currentValue;
        }
        int transitionId = typedArray.getResourceId(id, 0);
        Transition transition = defaultValue;
        if (transitionId != 0 && transitionId != com.android.internal.R.transition.no_transition) {
            TransitionInflater inflater = TransitionInflater.from(context);
            transition = inflater.inflateTransition(transitionId);
            if (transition instanceof TransitionSet &&
                    ((TransitionSet)transition).getTransitionCount() == 0) {
                transition = null;
            }
        }
        return transition;
    }

    private AnimationInfo ensureAnimationInfo() {
        if (mAnimationInfo == null) {
            mAnimationInfo = new AnimationInfo();
        }
        return mAnimationInfo;
    }

    int getNextAnim() {
        if (mAnimationInfo == null) {
            return 0;
        }
        return mAnimationInfo.mNextAnim;
    }

    void setNextAnim(int animResourceId) {
        if (mAnimationInfo == null && animResourceId == 0) {
            return; // no change!
        }
        ensureAnimationInfo().mNextAnim = animResourceId;
    }

    int getNextTransition() {
        if (mAnimationInfo == null) {
            return 0;
        }
        return mAnimationInfo.mNextTransition;
    }

    void setNextTransition(int nextTransition, int nextTransitionStyle) {
        if (mAnimationInfo == null && nextTransition == 0 && nextTransitionStyle == 0) {
            return; // no change!
        }
        ensureAnimationInfo();
        mAnimationInfo.mNextTransition = nextTransition;
        mAnimationInfo.mNextTransitionStyle = nextTransitionStyle;
    }

    int getNextTransitionStyle() {
        if (mAnimationInfo == null) {
            return 0;
        }
        return mAnimationInfo.mNextTransitionStyle;
    }

    SharedElementCallback getEnterTransitionCallback() {
        if (mAnimationInfo == null) {
            return SharedElementCallback.NULL_CALLBACK;
        }
        return mAnimationInfo.mEnterTransitionCallback;
    }

    SharedElementCallback getExitTransitionCallback() {
        if (mAnimationInfo == null) {
            return SharedElementCallback.NULL_CALLBACK;
        }
        return mAnimationInfo.mExitTransitionCallback;
    }

    Animator getAnimatingAway() {
        if (mAnimationInfo == null) {
            return null;
        }
        return mAnimationInfo.mAnimatingAway;
    }

    void setAnimatingAway(Animator animator) {
        ensureAnimationInfo().mAnimatingAway = animator;
    }

    int getStateAfterAnimating() {
        if (mAnimationInfo == null) {
            return 0;
        }
        return mAnimationInfo.mStateAfterAnimating;
    }

    void setStateAfterAnimating(int state) {
        ensureAnimationInfo().mStateAfterAnimating = state;
    }

    boolean isPostponed() {
        if (mAnimationInfo == null) {
            return false;
        }
        return mAnimationInfo.mEnterTransitionPostponed;
    }

    boolean isHideReplaced() {
        if (mAnimationInfo == null) {
            return false;
        }
        return mAnimationInfo.mIsHideReplaced;
    }

    void setHideReplaced(boolean replaced) {
        ensureAnimationInfo().mIsHideReplaced = replaced;
    }

    
Used internally to be notified when Fragment.startPostponedEnterTransition() has been called. This listener will only be called once and then be removed from the listeners. 
/**
     * Used internally to be notified when {@link #startPostponedEnterTransition()} has
     * been called. This listener will only be called once and then be removed from the
     * listeners.
     */
    interface OnStartEnterTransitionListener {
        void onStartEnterTransition();
        void startListening();
    }

    
Contains all the animation and transition information for a fragment. This will only
be instantiated for Fragments that have Views.

/**
     * Contains all the animation and transition information for a fragment. This will only
     * be instantiated for Fragments that have Views.
     */
    static class AnimationInfo {
        // Non-null if the fragment's view hierarchy is currently animating away,
        // meaning we need to wait a bit on completely destroying it.  This is the
        // animation that is running.
        Animator mAnimatingAway;

        // If mAnimatingAway != null, this is the state we should move to once the
        // animation is done.
        int mStateAfterAnimating;

        // If app has requested a specific animation, this is the one to use.
        int mNextAnim;

        // If app has requested a specific transition, this is the one to use.
        int mNextTransition;

        // If app has requested a specific transition style, this is the one to use.
        int mNextTransitionStyle;

        private Transition mEnterTransition = null;
        private Transition mReturnTransition = USE_DEFAULT_TRANSITION;
        private Transition mExitTransition = null;
        private Transition mReenterTransition = USE_DEFAULT_TRANSITION;
        private Transition mSharedElementEnterTransition = null;
        private Transition mSharedElementReturnTransition = USE_DEFAULT_TRANSITION;
        private Boolean mAllowReturnTransitionOverlap;
        private Boolean mAllowEnterTransitionOverlap;

        SharedElementCallback mEnterTransitionCallback = SharedElementCallback.NULL_CALLBACK;
        SharedElementCallback mExitTransitionCallback = SharedElementCallback.NULL_CALLBACK;

        // True when postponeEnterTransition has been called and startPostponeEnterTransition
        // hasn't been called yet.
        boolean mEnterTransitionPostponed;

        // Listener to wait for startPostponeEnterTransition. After being called, it will
        // be set to null
        OnStartEnterTransitionListener mStartEnterTransitionListener;

        // True if the View was hidden, but the transition is handling the hide
        boolean mIsHideReplaced;
    }
}