https://source.android.com/ 
/*
 * Copyright (C) 2006 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.annotation.CallSuper;
import android.content.ComponentCallbacks;
import android.content.ComponentCallbacks2;
import android.content.Context;
import android.content.ContextWrapper;
import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.util.Log;
import android.view.autofill.AutofillManager;

import java.util.ArrayList;


Base class for maintaining global application state. You can provide your own
implementation by creating a subclass and specifying the fully-qualified name
of this subclass as the "android:name" attribute in your
AndroidManifest.xml's <application> tag. The Application
class, or your subclass of the Application class, is instantiated before any
other class when the process for your application/package is created.

Note: There is normally no need to subclass Application. In most situations, static singletons can provide the same functionality in a more modular way. If your singleton needs a global context (for example to register broadcast receivers), include Context.getApplicationContext() as a Context argument when invoking your singleton's getInstance() method.



/**
 * Base class for maintaining global application state. You can provide your own
 * implementation by creating a subclass and specifying the fully-qualified name
 * of this subclass as the <code>"android:name"</code> attribute in your
 * AndroidManifest.xml's <code>&lt;application&gt;</code> tag. The Application
 * class, or your subclass of the Application class, is instantiated before any
 * other class when the process for your application/package is created.
 *
 * <p class="note"><strong>Note: </strong>There is normally no need to subclass
 * Application.  In most situations, static singletons can provide the same
 * functionality in a more modular way.  If your singleton needs a global
 * context (for example to register broadcast receivers), include
 * {@link android.content.Context#getApplicationContext() Context.getApplicationContext()}
 * as a {@link android.content.Context} argument when invoking your singleton's
 * <code>getInstance()</code> method.
 * </p>
 */
public class Application extends ContextWrapper implements ComponentCallbacks2 {
    private static final String TAG = "Application";
    private ArrayList<ComponentCallbacks> mComponentCallbacks =
            new ArrayList<ComponentCallbacks>();
    private ArrayList<ActivityLifecycleCallbacks> mActivityLifecycleCallbacks =
            new ArrayList<ActivityLifecycleCallbacks>();
    private ArrayList<OnProvideAssistDataListener> mAssistCallbacks = null;

    
@hide
/** @hide */
    public LoadedApk mLoadedApk;

    public interface ActivityLifecycleCallbacks {
        void onActivityCreated(Activity activity, Bundle savedInstanceState);
        void onActivityStarted(Activity activity);
        void onActivityResumed(Activity activity);
        void onActivityPaused(Activity activity);
        void onActivityStopped(Activity activity);
        void onActivitySaveInstanceState(Activity activity, Bundle outState);
        void onActivityDestroyed(Activity activity);
    }

    /**
     * Callback interface for use with {@link Application#registerOnProvideAssistDataListener}
     * and {@link Application#unregisterOnProvideAssistDataListener}.
     */
    public interface OnProvideAssistDataListener {
        
This is called when the user is requesting an assist, to build a full Intent.ACTION_ASSIST Intent with all of the context of the current application. You can override this method to place into the bundle anything you would like to appear in the Intent.EXTRA_ASSIST_CONTEXT part of the assist Intent. 
/**
         * This is called when the user is requesting an assist, to build a full
         * {@link Intent#ACTION_ASSIST} Intent with all of the context of the current
         * application.  You can override this method to place into the bundle anything
         * you would like to appear in the {@link Intent#EXTRA_ASSIST_CONTEXT} part
         * of the assist Intent.
         */
        public void onProvideAssistData(Activity activity, Bundle data);
    }

    public Application() {
        super(null);
    }

    
Called when the application is starting, before any activity, service,
or receiver objects (excluding content providers) have been created.

Implementations should be as quick as possible (for example using
lazy initialization of state) since the time spent in this function
directly impacts the performance of starting the first activity,
service, or receiver in a process.


If you override this method, be sure to call super.onCreate().


Be aware that direct boot may also affect callback order on Android VERSION_CODES.N and later devices. Until the user unlocks the device, only direct boot aware components are allowed to run. You should consider that all direct boot unaware components, including such ContentProvider, are disabled until user unlock happens, especially when component callback order matters.


/**
     * Called when the application is starting, before any activity, service,
     * or receiver objects (excluding content providers) have been created.
     *
     * <p>Implementations should be as quick as possible (for example using
     * lazy initialization of state) since the time spent in this function
     * directly impacts the performance of starting the first activity,
     * service, or receiver in a process.</p>
     *
     * <p>If you override this method, be sure to call {@code super.onCreate()}.</p>
     *
     * <p class="note">Be aware that direct boot may also affect callback order on
     * Android {@link android.os.Build.VERSION_CODES#N} and later devices.
     * Until the user unlocks the device, only direct boot aware components are
     * allowed to run. You should consider that all direct boot unaware
     * components, including such {@link android.content.ContentProvider}, are
     * disabled until user unlock happens, especially when component callback
     * order matters.</p>
     */
    @CallSuper
    public void onCreate() {
    }

    
This method is for use in emulated process environments.  It will
never be called on a production Android device, where processes are
removed by simply killing them; no user code (including this callback)
is executed when doing so.

/**
     * This method is for use in emulated process environments.  It will
     * never be called on a production Android device, where processes are
     * removed by simply killing them; no user code (including this callback)
     * is executed when doing so.
     */
    @CallSuper
    public void onTerminate() {
    }

    @CallSuper
    public void onConfigurationChanged(Configuration newConfig) {
        Object[] callbacks = collectComponentCallbacks();
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                ((ComponentCallbacks)callbacks[i]).onConfigurationChanged(newConfig);
            }
        }
    }

    @CallSuper
    public void onLowMemory() {
        Object[] callbacks = collectComponentCallbacks();
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                ((ComponentCallbacks)callbacks[i]).onLowMemory();
            }
        }
    }

    @CallSuper
    public void onTrimMemory(int level) {
        Object[] callbacks = collectComponentCallbacks();
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                Object c = callbacks[i];
                if (c instanceof ComponentCallbacks2) {
                    ((ComponentCallbacks2)c).onTrimMemory(level);
                }
            }
        }
    }

    public void registerComponentCallbacks(ComponentCallbacks callback) {
        synchronized (mComponentCallbacks) {
            mComponentCallbacks.add(callback);
        }
    }

    public void unregisterComponentCallbacks(ComponentCallbacks callback) {
        synchronized (mComponentCallbacks) {
            mComponentCallbacks.remove(callback);
        }
    }

    public void registerActivityLifecycleCallbacks(ActivityLifecycleCallbacks callback) {
        synchronized (mActivityLifecycleCallbacks) {
            mActivityLifecycleCallbacks.add(callback);
        }
    }

    public void unregisterActivityLifecycleCallbacks(ActivityLifecycleCallbacks callback) {
        synchronized (mActivityLifecycleCallbacks) {
            mActivityLifecycleCallbacks.remove(callback);
        }
    }

    public void registerOnProvideAssistDataListener(OnProvideAssistDataListener callback) {
        synchronized (this) {
            if (mAssistCallbacks == null) {
                mAssistCallbacks = new ArrayList<OnProvideAssistDataListener>();
            }
            mAssistCallbacks.add(callback);
        }
    }

    public void unregisterOnProvideAssistDataListener(OnProvideAssistDataListener callback) {
        synchronized (this) {
            if (mAssistCallbacks != null) {
                mAssistCallbacks.remove(callback);
            }
        }
    }

    
Returns the name of the current process. A package's default process name
is the same as its package name. Non-default processes will look like
"$PACKAGE_NAME:$NAME", where $NAME corresponds to an android:process
attribute within AndroidManifest.xml.

/**
     * Returns the name of the current process. A package's default process name
     * is the same as its package name. Non-default processes will look like
     * "$PACKAGE_NAME:$NAME", where $NAME corresponds to an android:process
     * attribute within AndroidManifest.xml.
     */
    public static String getProcessName() {
        return ActivityThread.currentProcessName();
    }

    // ------------------ Internal API ------------------

    
@hide
/**
     * @hide
     */
    /* package */ final void attach(Context context) {
        attachBaseContext(context);
        mLoadedApk = ContextImpl.getImpl(context).mPackageInfo;
    }

    /* package */ void dispatchActivityCreated(Activity activity, Bundle savedInstanceState) {
        Object[] callbacks = collectActivityLifecycleCallbacks();
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                ((ActivityLifecycleCallbacks)callbacks[i]).onActivityCreated(activity,
                        savedInstanceState);
            }
        }
    }

    /* package */ void dispatchActivityStarted(Activity activity) {
        Object[] callbacks = collectActivityLifecycleCallbacks();
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                ((ActivityLifecycleCallbacks)callbacks[i]).onActivityStarted(activity);
            }
        }
    }

    /* package */ void dispatchActivityResumed(Activity activity) {
        Object[] callbacks = collectActivityLifecycleCallbacks();
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                ((ActivityLifecycleCallbacks)callbacks[i]).onActivityResumed(activity);
            }
        }
    }

    /* package */ void dispatchActivityPaused(Activity activity) {
        Object[] callbacks = collectActivityLifecycleCallbacks();
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                ((ActivityLifecycleCallbacks)callbacks[i]).onActivityPaused(activity);
            }
        }
    }

    /* package */ void dispatchActivityStopped(Activity activity) {
        Object[] callbacks = collectActivityLifecycleCallbacks();
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                ((ActivityLifecycleCallbacks)callbacks[i]).onActivityStopped(activity);
            }
        }
    }

    /* package */ void dispatchActivitySaveInstanceState(Activity activity, Bundle outState) {
        Object[] callbacks = collectActivityLifecycleCallbacks();
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                ((ActivityLifecycleCallbacks)callbacks[i]).onActivitySaveInstanceState(activity,
                        outState);
            }
        }
    }

    /* package */ void dispatchActivityDestroyed(Activity activity) {
        Object[] callbacks = collectActivityLifecycleCallbacks();
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                ((ActivityLifecycleCallbacks)callbacks[i]).onActivityDestroyed(activity);
            }
        }
    }

    private Object[] collectComponentCallbacks() {
        Object[] callbacks = null;
        synchronized (mComponentCallbacks) {
            if (mComponentCallbacks.size() > 0) {
                callbacks = mComponentCallbacks.toArray();
            }
        }
        return callbacks;
    }

    private Object[] collectActivityLifecycleCallbacks() {
        Object[] callbacks = null;
        synchronized (mActivityLifecycleCallbacks) {
            if (mActivityLifecycleCallbacks.size() > 0) {
                callbacks = mActivityLifecycleCallbacks.toArray();
            }
        }
        return callbacks;
    }

    /* package */ void dispatchOnProvideAssistData(Activity activity, Bundle data) {
        Object[] callbacks;
        synchronized (this) {
            if (mAssistCallbacks == null) {
                return;
            }
            callbacks = mAssistCallbacks.toArray();
        }
        if (callbacks != null) {
            for (int i=0; i<callbacks.length; i++) {
                ((OnProvideAssistDataListener)callbacks[i]).onProvideAssistData(activity, data);
            }
        }
    }

    
@hide
/** @hide */
    @Override
    public AutofillManager.AutofillClient getAutofillClient() {
        final AutofillManager.AutofillClient client = super.getAutofillClient();
        if (client != null) {
            return client;
        }
        if (android.view.autofill.Helper.sVerbose) {
            Log.v(TAG, "getAutofillClient(): null on super, trying to find activity thread");
        }
        // Okay, ppl use the application context when they should not. This breaks
        // autofill among other things. We pick the focused activity since autofill
        // interacts only with the currently focused activity and we need the fill
        // client only if a call comes from the focused activity. Sigh...
        final ActivityThread activityThread = ActivityThread.currentActivityThread();
        if (activityThread == null) {
            return null;
        }
        final int activityCount = activityThread.mActivities.size();
        for (int i = 0; i < activityCount; i++) {
            final ActivityThread.ActivityClientRecord record =
                    activityThread.mActivities.valueAt(i);
            if (record == null) {
                continue;
            }
            final Activity activity = record.activity;
            if (activity == null) {
                continue;
            }
            if (activity.getWindow().getDecorView().hasFocus()) {
                if (android.view.autofill.Helper.sVerbose) {
                    Log.v(TAG, "getAutofillClient(): found activity for " + this + ": " + activity);
                }
                return activity;
            }
        }
        if (android.view.autofill.Helper.sVerbose) {
            Log.v(TAG, "getAutofillClient(): none of the " + activityCount + " activities on "
                    + this + " have focus");
        }
        return null;
    }
}