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 * Copyright (c) 2010, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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package javafx.collections;

import com.sun.javafx.collections.ListListenerHelper;
import com.sun.javafx.collections.MapListenerHelper;
import com.sun.javafx.collections.SetListenerHelper;
import java.lang.reflect.Array;
import java.util.AbstractList;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Random;
import java.util.Set;

import javafx.beans.InvalidationListener;

import com.sun.javafx.collections.ObservableListWrapper;
import com.sun.javafx.collections.ObservableMapWrapper;
import com.sun.javafx.collections.ObservableSetWrapper;
import com.sun.javafx.collections.MapAdapterChange;
import com.sun.javafx.collections.ObservableFloatArrayImpl;
import com.sun.javafx.collections.ObservableIntegerArrayImpl;
import com.sun.javafx.collections.ObservableSequentialListWrapper;
import com.sun.javafx.collections.SetAdapterChange;
import com.sun.javafx.collections.SortableList;
import com.sun.javafx.collections.SourceAdapterChange;
import java.util.RandomAccess;
import javafx.beans.Observable;
import javafx.collections.ListChangeListener.Change;
import javafx.util.Callback;

Utility class that consists of static methods that are 1:1 copies of java.util.Collections methods.



The wrapper methods (like synchronizedObservableList or emptyObservableList) has exactly the same
functionality as the methods in Collections, with exception that they return ObservableList and are
therefore suitable for methods that require ObservableList on input.



The utility methods are here mainly for performance reasons. All methods are optimized in a way that
they yield only limited number of notifications. On the other hand, java.util.Collections methods
might call "modification methods" on an ObservableList multiple times, resulting in a number of notifications.
Since:
JavaFX 2.0/**
 * Utility class that consists of static methods that are 1:1 copies of java.util.Collections methods.
 * <br><br>
 * The wrapper methods (like synchronizedObservableList or emptyObservableList) has exactly the same
 * functionality as the methods in Collections, with exception that they return ObservableList and are
 * therefore suitable for methods that require ObservableList on input.
 * <br><br>
 * The utility methods are here mainly for performance reasons. All methods are optimized in a way that
 * they yield only limited number of notifications. On the other hand, java.util.Collections methods
 * might call "modification methods" on an ObservableList multiple times, resulting in a number of notifications.
 *
 * @since JavaFX 2.0
 */
public class FXCollections {
    
Not to be instantiated. /** Not to be instantiated. */
    private FXCollections() { }

    
Constructs an ObservableList that is backed by the specified list.
Mutation operations on the ObservableList instance will be reported
to observers that have registered on that instance.

Note that mutation operations made directly to the underlying list are
not reported to observers of any ObservableList that
wraps it.
Params:
list – a concrete List that backs this ObservableList
Type parameters:
<E> – The type of List to be wrapped
Returns:
a newly created ObservableList/**
     * Constructs an ObservableList that is backed by the specified list.
     * Mutation operations on the ObservableList instance will be reported
     * to observers that have registered on that instance.<br>
     * Note that mutation operations made directly to the underlying list are
     * <em>not</em> reported to observers of any ObservableList that
     * wraps it.
     *
     * @param <E> The type of List to be wrapped
     * @param list a concrete List that backs this ObservableList
     * @return a newly created ObservableList
     */
    public static <E> ObservableList<E> observableList(List<E> list) {
        if (list == null) {
            throw new NullPointerException();
        }
        return list instanceof RandomAccess ? new ObservableListWrapper<E>(list) :
                new ObservableSequentialListWrapper<E>(list);
    }

    
Constructs an ObservableList that is backed by the specified list.
Mutation operations on the ObservableList instance will be reported
to observers that have registered on that instance.

Note that mutation operations made directly to the underlying list are
not reported to observers of any ObservableList that
wraps it.


This list also reports mutations of the elements in it by using extractor.
Observable objects returned by extractor (applied to each list element) are listened for changes
and transformed into "update" change of ListChangeListener.
Params:
list – a concrete List that backs this ObservableList
extractor – element to Observable[] convertor
Type parameters:
<E> – The type of List to be wrapped
Since:
JavaFX 2.1
Returns:
a newly created ObservableList/**
     * Constructs an ObservableList that is backed by the specified list.
     * Mutation operations on the ObservableList instance will be reported
     * to observers that have registered on that instance.<br>
     * Note that mutation operations made directly to the underlying list are
     * <em>not</em> reported to observers of any ObservableList that
     * wraps it.
     * <br>
     * This list also reports mutations of the elements in it by using <code>extractor</code>.
     * Observable objects returned by extractor (applied to each list element) are listened for changes
     * and transformed into "update" change of ListChangeListener.
     *
     * @param <E> The type of List to be wrapped
     * @param list a concrete List that backs this ObservableList
     * @param extractor element to Observable[] convertor
     * @since JavaFX 2.1
     * @return a newly created ObservableList
     */
    public static <E> ObservableList<E> observableList(List<E> list, Callback<E, Observable[]> extractor) {
        if (list == null || extractor == null) {
            throw new NullPointerException();
        }
        return list instanceof RandomAccess ? new ObservableListWrapper<E>(list, extractor) :
            new ObservableSequentialListWrapper<E>(list, extractor);
    }

    
Constructs an ObservableMap that is backed by the specified map.
Mutation operations on the ObservableMap instance will be reported
to observers that have registered on that instance.

Note that mutation operations made directly to the underlying map are not
reported to observers of any ObservableMap that wraps it.
Params:
map – a Map that backs this ObservableMap
Type parameters:
<K> – the type of the wrapped key
<V> – the type of the wrapped value
Returns:
a newly created ObservableMap/**
     * Constructs an ObservableMap that is backed by the specified map.
     * Mutation operations on the ObservableMap instance will be reported
     * to observers that have registered on that instance.<br>
     * Note that mutation operations made directly to the underlying map are <em>not</em>
     * reported to observers of any ObservableMap that wraps it.
     * @param <K> the type of the wrapped key
     * @param <V> the type of the wrapped value
     * @param map a Map that backs this ObservableMap
     * @return a newly created ObservableMap
     */
    public static <K, V> ObservableMap<K, V> observableMap(Map<K, V> map) {
        if (map == null) {
            throw new NullPointerException();
        }
        return new ObservableMapWrapper<K, V>(map);
    }

    
Constructs an ObservableSet that is backed by the specified set.
Mutation operations on the ObservableSet instance will be reported
to observers that have registered on that instance.

Note that mutation operations made directly to the underlying set are not
reported to observers of any ObservableSet that wraps it.
Params:
set – a Set that backs this ObservableSet
Type parameters:
<E> – The type of List to be wrapped
Returns:
a newly created ObservableSet
Since:
JavaFX 2.1/**
     * Constructs an ObservableSet that is backed by the specified set.
     * Mutation operations on the ObservableSet instance will be reported
     * to observers that have registered on that instance.<br>
     * Note that mutation operations made directly to the underlying set are <em>not</em>
     * reported to observers of any ObservableSet that wraps it.
     * @param <E> The type of List to be wrapped
     * @param set a Set that backs this ObservableSet
     * @return a newly created ObservableSet
     * @since JavaFX 2.1
     */
    public static <E> ObservableSet<E> observableSet(Set<E> set) {
        if (set == null) {
            throw new NullPointerException();
        }
        return new ObservableSetWrapper<E>(set);
    }

    
Constructs an ObservableSet backed by a HashSet
that contains all the specified elements.
Params:
elements – elements that will be added into returned ObservableSet
Type parameters:
<E> – The type of List to be wrapped
Returns:
a newly created ObservableSet
Since:
JavaFX 2.1/**
     * Constructs an ObservableSet backed by a HashSet
     * that contains all the specified elements.
     * @param <E> The type of List to be wrapped
     * @param elements elements that will be added into returned ObservableSet
     * @return a newly created ObservableSet
     * @since JavaFX 2.1
     */
    public static <E> ObservableSet<E> observableSet(E... elements) {
        if (elements == null) {
            throw new NullPointerException();
        }
        Set<E> set = new HashSet<E>(elements.length);
        Collections.addAll(set, elements);
        return new ObservableSetWrapper<E>(set);
    }

    
Constructs a read-only interface to the specified ObservableMap. Only
mutation operations made to the underlying ObservableMap will be reported
to observers that have registered on the unmodifiable instance. This allows
clients to track changes in a Map but disallows the ability to modify it.
Params:
map – an ObservableMap that is to be monitored by this interface
Type parameters:
<K> – the type of the wrapped key
<V> – the type of the wrapped value
Returns:
a newly created UnmodifiableObservableMap/**
     * Constructs a read-only interface to the specified ObservableMap. Only
     * mutation operations made to the underlying ObservableMap will be reported
     * to observers that have registered on the unmodifiable instance. This allows
     * clients to track changes in a Map but disallows the ability to modify it.
     * @param <K> the type of the wrapped key
     * @param <V> the type of the wrapped value
     * @param map an ObservableMap that is to be monitored by this interface
     * @return a newly created UnmodifiableObservableMap
     */
    public static <K, V> ObservableMap<K, V> unmodifiableObservableMap(ObservableMap<K, V> map) {
        if (map == null) {
            throw new NullPointerException();
        }
        return new com.sun.javafx.collections.UnmodifiableObservableMap<K, V>(map);
    }

    
Creates and returns a typesafe wrapper on top of provided observable map.
Params:
map – an Observable map to be wrapped
keyType – the type of key that map is permitted to hold
valueType – the type of value that map is permitted to hold
Type parameters:
<K> – the type of the wrapped key
<V> – the type of the wrapped value
See Also:
Collections.checkedMap(Map<Object,Object>, Class<Object>, Class<Object>)
Returns:
a dynamically typesafe view of the specified map
Since:
JavaFX 8.0/**
     * Creates and returns a typesafe wrapper on top of provided observable map.
     * @param <K> the type of the wrapped key
     * @param <V> the type of the wrapped value
     * @param map an Observable map to be wrapped
     * @param keyType the type of key that {@code map} is permitted to hold
     * @param valueType the type of value that {@code map} is permitted to hold
     * @return a dynamically typesafe view of the specified map
     * @see Collections#checkedMap(java.util.Map, java.lang.Class, java.lang.Class)
     * @since JavaFX 8.0
     */
    public static <K, V> ObservableMap<K, V> checkedObservableMap(ObservableMap<K, V> map, Class<K> keyType, Class<V> valueType) {
        if (map == null || keyType == null || valueType == null) {
            throw new NullPointerException();
        }
        return new CheckedObservableMap<K, V>(map, keyType, valueType);
    }

    
Creates and returns a synchronized wrapper on top of provided observable map.
Params:
map – the map to be "wrapped" in a synchronized map.
Type parameters:
<K> – the type of the wrapped key
<V> – the type of the wrapped value
See Also:
Collections.synchronizedMap(Map<Object,Object>)
Returns:
A synchronized version of the observable map
Since:
JavaFX 8.0/**
     * Creates and returns a synchronized wrapper on top of provided observable map.
     * @param <K> the type of the wrapped key
     * @param <V> the type of the wrapped value
     * @param  map the map to be "wrapped" in a synchronized map.
     * @return A synchronized version of the observable map
     * @see Collections#synchronizedMap(java.util.Map)
     * @since JavaFX 8.0
     */
    public static <K, V> ObservableMap<K, V> synchronizedObservableMap(ObservableMap<K, V> map) {
        if (map == null) {
            throw new NullPointerException();
        }
        return new SynchronizedObservableMap<K, V>(map);
    }

    private static ObservableMap EMPTY_OBSERVABLE_MAP = new EmptyObservableMap();

    
Creates an empty unmodifiable observable map.
Type parameters:
<K> – the type of the wrapped key
<V> – the type of the wrapped value
See Also:
Collections.emptyMap()
Returns:
An empty unmodifiable observable map
Since:
JavaFX 8.0/**
     * Creates an empty unmodifiable observable map.
     * @param <K> the type of the wrapped key
     * @param <V> the type of the wrapped value
     * @return An empty unmodifiable observable map
     * @see Collections#emptyMap()
     * @since JavaFX 8.0
     */
    @SuppressWarnings("unchecked")
    public static <K, V> ObservableMap<K, V> emptyObservableMap() {
        return EMPTY_OBSERVABLE_MAP;
    }

    
Creates a new empty observable integer array.
Returns:
a newly created ObservableIntegerArray
Since:
JavaFX 8.0/**
     * Creates a new empty observable integer array.
     * @return a newly created ObservableIntegerArray
     * @since JavaFX 8.0
     */
    public static ObservableIntegerArray observableIntegerArray() {
        return new ObservableIntegerArrayImpl();
    }

    
Creates a new observable integer array with values set to it. 
Params:
values – the values that will be in the new observable integer array
Returns:
a newly created ObservableIntegerArray
Since:
JavaFX 8.0/**
     * Creates a new observable integer array with {@code values} set to it.
     * @param values the values that will be in the new observable integer array
     * @return a newly created ObservableIntegerArray
     * @since JavaFX 8.0
     */
    public static ObservableIntegerArray observableIntegerArray(int... values) {
        return new ObservableIntegerArrayImpl(values);
    }

    
Creates a new observable integer array with copy of elements in given array. 
Params:
array – observable integer array to copy
Returns:
a newly created ObservableIntegerArray
Since:
JavaFX 8.0/**
     * Creates a new observable integer array with copy of elements in given
     * {@code array}.
     * @param array observable integer array to copy
     * @return a newly created ObservableIntegerArray
     * @since JavaFX 8.0
     */
    public static ObservableIntegerArray observableIntegerArray(ObservableIntegerArray array) {
        return new ObservableIntegerArrayImpl(array);
    }

    
Creates a new empty observable float array.
Returns:
a newly created ObservableFloatArray
Since:
JavaFX 8.0/**
     * Creates a new empty observable float array.
     * @return a newly created ObservableFloatArray
     * @since JavaFX 8.0
     */
    public static ObservableFloatArray observableFloatArray() {
        return new ObservableFloatArrayImpl();
    }

    
Creates a new observable float array with values set to it. 
Params:
values – the values that will be in the new observable float array
Returns:
a newly created ObservableFloatArray
Since:
JavaFX 8.0/**
     * Creates a new observable float array with {@code values} set to it.
     * @param values the values that will be in the new observable float array
     * @return a newly created ObservableFloatArray
     * @since JavaFX 8.0
     */
    public static ObservableFloatArray observableFloatArray(float... values) {
        return new ObservableFloatArrayImpl(values);
    }

    
Creates a new observable float array with copy of elements in given array. 
Params:
array – observable float array to copy
Returns:
a newly created ObservableFloatArray
Since:
JavaFX 8.0/**
     * Creates a new observable float array with copy of elements in given
     * {@code array}.
     * @param array observable float array to copy
     * @return a newly created ObservableFloatArray
     * @since JavaFX 8.0
     */
    public static ObservableFloatArray observableFloatArray(ObservableFloatArray array) {
        return new ObservableFloatArrayImpl(array);
    }

    
Creates a new empty observable list that is backed by an arraylist.
Type parameters:
<E> – The type of List to be wrapped
See Also:
observableList(List)
Returns:
a newly created ObservableList/**
     * Creates a new empty observable list that is backed by an arraylist.
     * @see #observableList(java.util.List)
     * @param <E> The type of List to be wrapped
     * @return a newly created ObservableList
     */
    @SuppressWarnings("unchecked")
    public static <E> ObservableList<E> observableArrayList() {
        return observableList(new ArrayList());
    }

    
Creates a new empty observable list backed by an arraylist.
This list reports element updates.
Params:
extractor – element to Observable[] convertor. Observable objects are listened for changes on the element.
Type parameters:
<E> – The type of List to be wrapped
See Also:
observableList(List<Object>, Callback<Object,Observable[]>)
Since:
JavaFX 2.1
Returns:
a newly created ObservableList/**
     * Creates a new empty observable list backed by an arraylist.
     *
     * This list reports element updates.
     * @param <E> The type of List to be wrapped
     * @param extractor element to Observable[] convertor. Observable objects are listened for changes on the element.
     * @see #observableList(java.util.List, javafx.util.Callback)
     * @since JavaFX 2.1
     * @return a newly created ObservableList
     */
    public static <E> ObservableList<E> observableArrayList(Callback<E, Observable[]> extractor) {
        return observableList(new ArrayList(), extractor);
    }

    
Creates a new observable array list with items added to it. 
Params:
items – the items that will be in the new observable ArrayList
Type parameters:
<E> – The type of List to be wrapped
See Also:
observableArrayList()
Returns:
a newly created observableArrayList/**
     * Creates a new observable array list with {@code items} added to it.
     * @param <E> The type of List to be wrapped
     * @param items the items that will be in the new observable ArrayList
     * @return a newly created observableArrayList
     * @see #observableArrayList()
     */
    public static <E> ObservableList<E> observableArrayList(E... items) {
        ObservableList<E> list = observableArrayList();
        list.addAll(items);
        return list;
    }

    
Creates a new observable array list and adds a content of collection col to it. 
Params:
col – a collection which content should be added to the observableArrayList
Type parameters:
<E> – The type of List to be wrapped
Returns:
a newly created observableArrayList/**
     * Creates a new observable array list and adds a content of collection {@code col}
     * to it.
     * @param <E> The type of List to be wrapped
     * @param col a collection which content should be added to the observableArrayList
     * @return a newly created observableArrayList
     */
    public static <E> ObservableList<E> observableArrayList(Collection<? extends E> col) {
        ObservableList<E> list = observableArrayList();
        list.addAll(col);
        return list;
    }

    
Creates a new empty observable map that is backed by a HashMap.
Type parameters:
<K> – the type of the wrapped key
<V> – the type of the wrapped value
Returns:
a newly created observable HashMap/**
     * Creates a new empty observable map that is backed by a HashMap.
     * @param <K> the type of the wrapped key
     * @param <V> the type of the wrapped value
     * @return a newly created observable HashMap
     */
    public static <K,V> ObservableMap<K,V> observableHashMap() {
        return observableMap(new HashMap<K, V>());
    }

    
Concatenates more observable lists into one. The resulting list
would be backed by an arraylist.
Params:
lists – lists to concatenate
Type parameters:
<E> – The type of List to be wrapped
Returns:
new observable array list concatenated from the arguments/**
     * Concatenates more observable lists into one. The resulting list
     * would be backed by an arraylist.
     * @param <E> The type of List to be wrapped
     * @param lists lists to concatenate
     * @return new observable array list concatenated from the arguments
     */
    public static <E> ObservableList<E> concat(ObservableList<E>... lists) {
        if (lists.length == 0 ) {
            return observableArrayList();
        }
        if (lists.length == 1) {
            return observableArrayList(lists[0]);
        }
        ArrayList<E> backingList = new ArrayList<E>();
        for (ObservableList<E> s : lists) {
            backingList.addAll(s);
        }

        return observableList(backingList);
    }

    
Creates and returns unmodifiable wrapper list on top of provided observable list.
Params:
list –  an ObservableList that is to be wrapped
Type parameters:
<E> – The type of List to be wrapped
See Also:
Collections.unmodifiableList(List<? extends Object>)
Returns:
an ObserableList wrapper that is unmodifiable/**
     * Creates and returns unmodifiable wrapper list on top of provided observable list.
     * @param list  an ObservableList that is to be wrapped
     * @param <E> The type of List to be wrapped
     * @return an ObserableList wrapper that is unmodifiable
     * @see Collections#unmodifiableList(java.util.List)
     */
    public static<E> ObservableList<E> unmodifiableObservableList(ObservableList<E> list) {
        if (list == null) {
            throw new NullPointerException();
        }
        return new UnmodifiableObservableListImpl<E>(list);
    }

    
Creates and returns a typesafe wrapper on top of provided observable list.
Params:
list –  an Observable list to be wrapped
type –  the type of element that list is permitted to hold
Type parameters:
<E> – The type of List to be wrapped
See Also:
Collections.checkedList(List<Object>, Class<Object>)
Returns:
a dynamically typesafe view of the specified list/**
     * Creates and returns a typesafe wrapper on top of provided observable list.
     * @param <E> The type of List to be wrapped
     * @param list  an Observable list to be wrapped
     * @param type   the type of element that {@code list} is permitted to hold
     * @return a dynamically typesafe view of the specified list
     * @see Collections#checkedList(java.util.List, java.lang.Class)
     */
    public static<E> ObservableList<E> checkedObservableList(ObservableList<E> list, Class<E> type) {
        if (list == null) {
            throw new NullPointerException();
        }
        return new CheckedObservableList<E>(list, type);
    }

    
Creates and returns a synchronized wrapper on top of provided observable list.
Params:
list – the list to be "wrapped" in a synchronized list.
Type parameters:
<E> – The type of List to be wrapped
See Also:
Collections.synchronizedList(List<Object>)
Returns:
A synchronized version of the observable list/**
     * Creates and returns a synchronized wrapper on top of provided observable list.
     * @param <E> The type of List to be wrapped
     * @param  list the list to be "wrapped" in a synchronized list.
     * @return A synchronized version of the observable list
     * @see Collections#synchronizedList(java.util.List)
     */
    public static<E> ObservableList<E> synchronizedObservableList(ObservableList<E> list) {
        if (list == null) {
            throw new NullPointerException();
        }
        return new SynchronizedObservableList<E>(list);
    }

    private static ObservableList EMPTY_OBSERVABLE_LIST = new EmptyObservableList();


    
Creates an empty unmodifiable observable list.
Type parameters:
<E> – The type of List to be wrapped
See Also:
Collections.emptyList()
Returns:
An empty unmodifiable observable list/**
     * Creates an empty unmodifiable observable list.
     * @param <E> The type of List to be wrapped
     * @return An empty unmodifiable observable list
     * @see Collections#emptyList()
     */
    @SuppressWarnings("unchecked")
    public static<E> ObservableList<E> emptyObservableList() {
        return EMPTY_OBSERVABLE_LIST;
    }

    
Creates an unmodifiable observable list with single element.
Params:
e – the only elements that will be contained in this singleton observable list
Type parameters:
<E> – The type of List to be wrapped
See Also:
Collections.singletonList(Object)
Returns:
a singleton observable list/**
     * Creates an unmodifiable observable list with single element.
     * @param <E> The type of List to be wrapped
     * @param e the only elements that will be contained in this singleton observable list
     * @return a singleton observable list
     * @see Collections#singletonList(java.lang.Object)
     */
    public static<E> ObservableList<E> singletonObservableList(E e) {
        return new SingletonObservableList<E>(e);
    }

    
Creates and returns unmodifiable wrapper on top of provided observable set.
Params:
set – an ObservableSet that is to be wrapped
Type parameters:
<E> – The type of List to be wrapped
See Also:
Collections.unmodifiableSet(Set<? extends Object>)
Returns:
an ObserableSet wrapper that is unmodifiable
Since:
JavaFX 8.0/**
     * Creates and returns unmodifiable wrapper on top of provided observable set.
     * @param <E> The type of List to be wrapped
     * @param set an ObservableSet that is to be wrapped
     * @return an ObserableSet wrapper that is unmodifiable
     * @see Collections#unmodifiableSet(java.util.Set)
     * @since JavaFX 8.0
     */
    public static<E> ObservableSet<E> unmodifiableObservableSet(ObservableSet<E> set) {
        if (set == null) {
            throw new NullPointerException();
        }
        return new UnmodifiableObservableSet<E>(set);
    }

    
Creates and returns a typesafe wrapper on top of provided observable set.
Params:
set – an Observable set to be wrapped
type –  the type of element that set is permitted to hold
Type parameters:
<E> – The type of List to be wrapped
See Also:
Collections.checkedSet(Set<Object>, Class<Object>)
Returns:
a dynamically typesafe view of the specified set
Since:
JavaFX 8.0/**
     * Creates and returns a typesafe wrapper on top of provided observable set.
     * @param <E> The type of List to be wrapped
     * @param set an Observable set to be wrapped
     * @param type  the type of element that {@code set} is permitted to hold
     * @return a dynamically typesafe view of the specified set
     * @see Collections#checkedSet(java.util.Set, java.lang.Class)
     * @since JavaFX 8.0
     */
    public static<E> ObservableSet<E> checkedObservableSet(ObservableSet<E> set, Class<E> type) {
        if (set == null) {
            throw new NullPointerException();
        }
        return new CheckedObservableSet<E>(set, type);
    }

    
Creates and returns a synchronized wrapper on top of provided observable set.
Params:
set – the set to be "wrapped" in a synchronized set.
Type parameters:
<E> – The type of List to be wrapped
See Also:
Collections.synchronizedSet(Set<Object>)
Returns:
A synchronized version of the observable set
Since:
JavaFX 8.0/**
     * Creates and returns a synchronized wrapper on top of provided observable set.
     * @param <E> The type of List to be wrapped
     * @param  set the set to be "wrapped" in a synchronized set.
     * @return A synchronized version of the observable set
     * @see Collections#synchronizedSet(java.util.Set)
     * @since JavaFX 8.0
     */
    public static<E> ObservableSet<E> synchronizedObservableSet(ObservableSet<E> set) {
        if (set == null) {
            throw new NullPointerException();
        }
        return new SynchronizedObservableSet<E>(set);
    }

    private static ObservableSet EMPTY_OBSERVABLE_SET = new EmptyObservableSet();

    
Creates an empty unmodifiable observable set.
Type parameters:
<E> – The type of List to be wrapped
See Also:
Collections.emptySet()
Returns:
An empty unmodifiable observable set
Since:
JavaFX 8.0/**
     * Creates an empty unmodifiable observable set.
     * @param <E> The type of List to be wrapped
     * @return An empty unmodifiable observable set
     * @see Collections#emptySet()
     * @since JavaFX 8.0
     */
    @SuppressWarnings("unchecked")
    public static<E> ObservableSet<E> emptyObservableSet() {
        return EMPTY_OBSERVABLE_SET;
    }

    
Copies elements from src to dest. Fires only one change notification on dest.
Params:
dest – the destination observable list
src – the source list
Type parameters:
<T> – The type of List to be wrapped
See Also:
Collections.copy(List<? super Object>, List<? extends Object>)/**
     * Copies elements from src to dest. Fires only <b>one</b> change notification on dest.
     * @param <T> The type of List to be wrapped
     * @param dest the destination observable list
     * @param src the source list
     * @see Collections#copy(java.util.List, java.util.List)
     */
    @SuppressWarnings("unchecked")
    public static <T> void copy(ObservableList<? super T> dest, List<? extends T> src) {
        final int srcSize = src.size();
        if (srcSize > dest.size()) {
            throw new IndexOutOfBoundsException("Source does not fit in dest");
        }
        T[] destArray = (T[]) dest.toArray();
        System.arraycopy(src.toArray(), 0, destArray, 0, srcSize);
        dest.setAll(destArray);
    }

    
Fills the provided list with obj. Fires only one change notification on the list.
Params:
list – the list to fill
obj – the object to fill the list with
Type parameters:
<T> – The type of List to be wrapped
See Also:
Collections.fill(List<? super Object>, Object)/**
     * Fills the provided list with obj. Fires only <b>one</b> change notification on the list.
     * @param <T> The type of List to be wrapped
     * @param list the list to fill
     * @param obj the object to fill the list with
     * @see Collections#fill(java.util.List, java.lang.Object)
     */
    @SuppressWarnings("unchecked")
    public static <T> void fill(ObservableList<? super T> list, T obj) {
        T[] newContent = (T[]) new Object[list.size()];
        Arrays.fill(newContent, obj);
        list.setAll(newContent);
    }

    
Replace all oldVal elements in the list with newVal element.
Fires only one change notification on the list.
Params:
list – the list which will have it's elements replaced
oldVal – the element that is going to be replace
newVal – the replacement
Type parameters:
<T> – The type of List to be wrapped
See Also:
Collections.replaceAll(List<Object>, Object, Object)
Returns:
true if the list was modified/**
     * Replace all oldVal elements in the list with newVal element.
     * Fires only <b>one</b> change notification on the list.
     * @param <T> The type of List to be wrapped
     * @param list the list which will have it's elements replaced
     * @param oldVal the element that is going to be replace
     * @param newVal the replacement
     * @return true if the list was modified
     * @see Collections#replaceAll(java.util.List, java.lang.Object, java.lang.Object)
     */
    @SuppressWarnings("unchecked")
    public static <T> boolean replaceAll(ObservableList<T> list, T oldVal, T newVal) {
        T[] newContent = (T[]) list.toArray();
        boolean modified = false;
        for (int i = 0 ; i < newContent.length; ++i) {
            if (newContent[i].equals(oldVal)) {
                newContent[i] = newVal;
                modified = true;
            }
        }
        if (modified) {
            list.setAll(newContent);
        }
        return modified;
    }

    
Reverse the order in the list
Fires only one change notification on the list.
Params:
list – the list to be reversed
See Also:
Collections.reverse(List<?>)/**
     * Reverse the order in the list
     * Fires only <b>one</b> change notification on the list.
     * @param list the list to be reversed
     * @see Collections#reverse(java.util.List)
     */
    @SuppressWarnings("unchecked")
    public static void reverse(ObservableList list) {
        Object[] newContent = list.toArray();
        for (int i = 0; i < newContent.length / 2; ++i) {
            Object tmp = newContent[i];
            newContent[i] = newContent[newContent.length - i - 1];
            newContent[newContent.length -i - 1] = tmp;
        }
        list.setAll(newContent);
    }

    
Rotates the list by distance.
Fires only one change notification on the list.
Params:
list – the list to be rotated
distance – the distance of rotation
See Also:
Collections.rotate(List<?>, int)/**
     * Rotates the list by distance.
     * Fires only <b>one</b> change notification on the list.
     * @param list the list to be rotated
     * @param distance the distance of rotation
     * @see Collections#rotate(java.util.List, int)
     */
    @SuppressWarnings("unchecked")
    public static void rotate(ObservableList list, int distance) {
        Object[] newContent = list.toArray();

        int size = list.size();
        distance = distance % size;
        if (distance < 0)
            distance += size;
        if (distance == 0)
            return;

        for (int cycleStart = 0, nMoved = 0; nMoved != size; cycleStart++) {
            Object displaced = newContent[cycleStart];
            Object tmp;
            int i = cycleStart;
            do {
                i += distance;
                if (i >= size)
                    i -= size;
                tmp = newContent[i];
                newContent[i] = displaced;
                displaced = tmp;
                nMoved ++;
            } while(i != cycleStart);
        }
        list.setAll(newContent);
    }

    
Shuffles all elements in the observable list.
Fires only one change notification on the list.
Params:
list – the list to shuffle
See Also:
Collections.shuffle(List<?>)/**
     * Shuffles all elements in the observable list.
     * Fires only <b>one</b> change notification on the list.
     * @param list the list to shuffle
     * @see Collections#shuffle(java.util.List)
     */
    public static void shuffle(ObservableList<?> list) {
        if (r == null) {
            r = new Random();
        }
        shuffle(list, r);
    }
    private static Random r;

    
Shuffles all elements in the observable list.
Fires only one change notification on the list.
Params:
list – the list to be shuffled
rnd – the random generator used for shuffling
See Also:
Collections.shuffle(List<?>, Random)/**
     * Shuffles all elements in the observable list.
     * Fires only <b>one</b> change notification on the list.
     * @param list the list to be shuffled
     * @param rnd the random generator used for shuffling
     * @see Collections#shuffle(java.util.List, java.util.Random)
     */
    @SuppressWarnings("unchecked")
    public static void shuffle(ObservableList list, Random rnd) {
        Object newContent[] = list.toArray();

        for (int i = list.size(); i > 1; i--) {
            swap(newContent, i - 1, rnd.nextInt(i));
        }

        list.setAll(newContent);
    }

    private static void swap(Object[] arr, int i, int j) {
        Object tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }

    
Sorts the provided observable list.
Fires only one change notification on the list.
Params:
list – the list to be sorted
Type parameters:
<T> – The type of List to be wrapped
See Also:
Collections.sort(List<Z#0-T#146>)/**
     * Sorts the provided observable list.
     * Fires only <b>one</b> change notification on the list.
     * @param <T> The type of List to be wrapped
     * @param list the list to be sorted
     * @see Collections#sort(java.util.List)
     */
    @SuppressWarnings("unchecked")
    public static <T extends Comparable<? super T>> void sort(ObservableList<T> list) {
        if (list instanceof SortableList) {
            ((SortableList<? extends T>)list).sort();
        } else {
            List<T> newContent = new ArrayList<T>(list);
            Collections.sort(newContent);
            list.setAll((Collection<T>)newContent);
        }
    }

    
Sorts the provided observable list using the c comparator.
Fires only one change notification on the list.
Params:
list – the list to sort
c – comparator used for sorting. Null if natural ordering is required.
Type parameters:
<T> – The type of List to be wrapped
See Also:
Collections.sort(List<Object>, Comparator<? super Object>)/**
     * Sorts the provided observable list using the c comparator.
     * Fires only <b>one</b> change notification on the list.
     * @param <T> The type of List to be wrapped
     * @param list the list to sort
     * @param c comparator used for sorting. Null if natural ordering is required.
     * @see Collections#sort(java.util.List, java.util.Comparator)
     */
    @SuppressWarnings("unchecked")
    public static <T> void sort(ObservableList<T> list, Comparator<? super T> c) {
        if (list instanceof SortableList) {
            ((SortableList<? extends T>)list).sort(c);
        } else {
            List<T> newContent = new ArrayList<T>(list);
            Collections.sort(newContent, c);
            list.setAll((Collection<T>)newContent);
        }
    }

    private static class EmptyObservableList<E> extends AbstractList<E> implements ObservableList<E> {

        private static final ListIterator iterator = new ListIterator() {

            @Override
            public boolean hasNext() {
                return false;
            }

            @Override
            public Object next() {
                throw new NoSuchElementException();
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException();
            }

            @Override
            public boolean hasPrevious() {
                return false;
            }

            @Override
            public Object previous() {
                throw new NoSuchElementException();
            }

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

            @Override
            public int previousIndex() {
                return -1;
            }

            @Override
            public void set(Object e) {
                throw new UnsupportedOperationException();
            }

            @Override
            public void add(Object e) {
                throw new UnsupportedOperationException();
            }
        };

        public EmptyObservableList() {
        }

        @Override
        public final void addListener(InvalidationListener listener) {
        }

        @Override
        public final void removeListener(InvalidationListener listener) {
        }


        @Override
        public void addListener(ListChangeListener<? super E> o) {
        }

        @Override
        public void removeListener(ListChangeListener<? super E> o) {
        }

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

        @Override
        public boolean contains(Object o) {
            return false;
        }

        @Override
        @SuppressWarnings("unchecked")
        public Iterator<E> iterator() {
            return iterator;
        }

        @Override
        public boolean containsAll(Collection<?> c) {
            return c.isEmpty();
        }

        @Override
        public E get(int index) {
            throw new IndexOutOfBoundsException();
        }

        @Override
        public int indexOf(Object o) {
            return -1;
        }

        @Override
        public int lastIndexOf(Object o) {
            return -1;
        }

        @Override
        @SuppressWarnings("unchecked")
        public ListIterator<E> listIterator() {
            return iterator;
        }

        @Override
        @SuppressWarnings("unchecked")
        public ListIterator<E> listIterator(int index) {
            if (index != 0) {
                throw new IndexOutOfBoundsException();
            }
            return iterator;
        }

        @Override
        public List<E> subList(int fromIndex, int toIndex) {
            if (fromIndex != 0 || toIndex != 0) {
                throw new IndexOutOfBoundsException();
            }
            return this;
        }

        @Override
        public boolean addAll(E... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean setAll(E... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean setAll(Collection<? extends E> col) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean removeAll(E... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean retainAll(E... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public void remove(int from, int to) {
            throw new UnsupportedOperationException();
        }
    }

    private static class SingletonObservableList<E> extends AbstractList<E> implements ObservableList<E> {

        private final E element;

        public SingletonObservableList(E element) {
            if (element == null) {
                throw new NullPointerException();
            }
            this.element = element;
        }

        @Override
        public boolean addAll(E... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean setAll(E... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean setAll(Collection<? extends E> col) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean removeAll(E... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean retainAll(E... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public void remove(int from, int to) {
            throw new UnsupportedOperationException();
        }

        @Override
        public void addListener(InvalidationListener listener) {
        }

        @Override
        public void removeListener(InvalidationListener listener) {
        }

        @Override
        public void addListener(ListChangeListener<? super E> o) {
        }

        @Override
        public void removeListener(ListChangeListener<? super E> o) {
        }

        @Override
        public int size() {
            return 1;
        }

        @Override
        public boolean isEmpty() {
            return false;
        }

        @Override
        public boolean contains(Object o) {
            return element.equals(o);
        }

        @Override
        public E get(int index) {
            if (index != 0) {
                throw new IndexOutOfBoundsException();
            }
            return element;
        }

    }

    private static class UnmodifiableObservableListImpl<T> extends ObservableListBase<T> implements ObservableList<T> {

        private final ObservableList<T> backingList;
        private final ListChangeListener<T> listener;

        public UnmodifiableObservableListImpl(ObservableList<T> backingList) {
            this.backingList = backingList;
            listener = c -> {
                fireChange(new SourceAdapterChange<T>(UnmodifiableObservableListImpl.this, c));
            };
            this.backingList.addListener(new WeakListChangeListener<T>(listener));
        }

        @Override
        public T get(int index) {
            return backingList.get(index);
        }

        @Override
        public int size() {
            return backingList.size();
        }

        @Override
        public boolean addAll(T... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean setAll(T... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean setAll(Collection<? extends T> col) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean removeAll(T... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean retainAll(T... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public void remove(int from, int to) {
            throw new UnsupportedOperationException();
        }

    }

    private static class SynchronizedList<T> implements List<T> {
        final Object mutex;
        private final List<T> backingList;

        SynchronizedList(List<T> list, Object mutex) {
            this.backingList = list;
            this.mutex = mutex;
        }

        @Override
        public int size() {
            synchronized(mutex) {
                return backingList.size();
            }
        }

        @Override
        public boolean isEmpty() {
            synchronized(mutex) {
                return backingList.isEmpty();
            }
        }

        @Override
        public boolean contains(Object o) {
            synchronized(mutex) {
                return backingList.contains(o);
            }
        }

        @Override
        public Iterator<T> iterator() {
            return backingList.iterator();
        }

        @Override
        public Object[] toArray() {
            synchronized(mutex)  {
                return backingList.toArray();
            }
        }

        @Override
        public <T> T[] toArray(T[] a) {
            synchronized(mutex) {
                return backingList.toArray(a);
            }
        }

        @Override
        public boolean add(T e) {
            synchronized(mutex) {
                return backingList.add(e);
            }
        }

        @Override
        public boolean remove(Object o) {
            synchronized(mutex) {
                return backingList.remove(o);
            }
        }

        @Override
        public boolean containsAll(Collection<?> c) {
            synchronized(mutex) {
                return backingList.containsAll(c);
            }
        }

        @Override
        public boolean addAll(Collection<? extends T> c) {
            synchronized(mutex) {
                return backingList.addAll(c);
            }
        }

        @Override
        public boolean addAll(int index, Collection<? extends T> c) {
            synchronized(mutex) {
                return backingList.addAll(index, c);

            }
        }

        @Override
        public boolean removeAll(Collection<?> c) {
            synchronized(mutex) {
                return backingList.removeAll(c);
            }
        }

        @Override
        public boolean retainAll(Collection<?> c) {
            synchronized(mutex) {
                return backingList.retainAll(c);
            }
        }

        @Override
        public void clear() {
            synchronized(mutex) {
                backingList.clear();
            }
        }

        @Override
        public T get(int index) {
            synchronized(mutex) {
                return backingList.get(index);
            }
        }

        @Override
        public T set(int index, T element) {
            synchronized(mutex) {
                return backingList.set(index, element);
            }
        }

        @Override
        public void add(int index, T element) {
            synchronized(mutex) {
                backingList.add(index, element);
            }
        }

        @Override
        public T remove(int index) {
            synchronized(mutex) {
                return backingList.remove(index);
            }
        }

        @Override
        public int indexOf(Object o) {
            synchronized(mutex) {
                return backingList.indexOf(o);
            }
        }

        @Override
        public int lastIndexOf(Object o) {
            synchronized(mutex) {
                return backingList.lastIndexOf(o);
            }
        }

        @Override
        public ListIterator<T> listIterator() {
            return backingList.listIterator();
        }

        @Override
        public ListIterator<T> listIterator(int index) {
            synchronized(mutex) {
                return backingList.listIterator(index);
            }
        }

        @Override
        public List<T> subList(int fromIndex, int toIndex) {
            synchronized(mutex) {
                return new SynchronizedList<T>(backingList.subList(fromIndex, toIndex),
                        mutex);
            }
        }

        @Override
        public String toString() {
            synchronized(mutex) {
                return backingList.toString();
            }
        }

        @Override
        public int hashCode() {
            synchronized(mutex) {
                return backingList.hashCode();
            }
        }

        @Override
        public boolean equals(Object o) {
            synchronized(mutex) {
                return backingList.equals(o);
            }
        }

    }

    private static class SynchronizedObservableList<T> extends SynchronizedList<T> implements ObservableList<T> {

        private ListListenerHelper helper;

        private final ObservableList<T> backingList;
        private final ListChangeListener<T> listener;

        SynchronizedObservableList(ObservableList<T> seq, Object mutex) {
            super(seq, mutex);
            this.backingList = seq;
            listener = c -> {
                ListListenerHelper.fireValueChangedEvent(helper, new SourceAdapterChange<T>(SynchronizedObservableList.this, c));
            };
            backingList.addListener(new WeakListChangeListener<T>(listener));
        }

        SynchronizedObservableList(ObservableList<T> seq) {
            this(seq, new Object());
        }

        @Override
        public boolean addAll(T... elements) {
            synchronized(mutex) {
                return backingList.addAll(elements);
            }
        }

        @Override
        public boolean setAll(T... elements) {
            synchronized(mutex) {
                return backingList.setAll(elements);
            }
        }

        @Override
        public boolean removeAll(T... elements) {
            synchronized(mutex) {
                return backingList.removeAll(elements);
            }
        }

        @Override
        public boolean retainAll(T... elements) {
            synchronized(mutex) {
                return backingList.retainAll(elements);
            }
        }

        @Override
        public void remove(int from, int to) {
            synchronized(mutex) {
                backingList.remove(from, to);
            }
        }

        @Override
        public boolean setAll(Collection<? extends T> col) {
            synchronized(mutex) {
                return backingList.setAll(col);
            }
        }

        @Override
        public final void addListener(InvalidationListener listener) {
            synchronized (mutex) {
                helper = ListListenerHelper.addListener(helper, listener);
            }
        }

        @Override
        public final void removeListener(InvalidationListener listener) {
            synchronized (mutex) {
                helper = ListListenerHelper.removeListener(helper, listener);
            }
        }

        @Override
        public void addListener(ListChangeListener<? super T> listener) {
            synchronized (mutex) {
                helper = ListListenerHelper.addListener(helper, listener);
            }
        }

        @Override
        public void removeListener(ListChangeListener<? super T> listener) {
            synchronized (mutex) {
                helper = ListListenerHelper.removeListener(helper, listener);
            }
        }


    }

    private static class CheckedObservableList<T> extends ObservableListBase<T> implements ObservableList<T> {

        private final ObservableList<T> list;
        private final Class<T> type;
        private final ListChangeListener<T> listener;

        CheckedObservableList(ObservableList<T> list, Class<T> type) {
            if (list == null || type == null) {
                throw new NullPointerException();
            }
            this.list = list;
            this.type = type;
            listener = c -> {
                fireChange(new SourceAdapterChange<T>(CheckedObservableList.this, c));
            };
            list.addListener(new WeakListChangeListener<T>(listener));
        }

        void typeCheck(Object o) {
            if (o != null && !type.isInstance(o)) {
                throw new ClassCastException("Attempt to insert "
                        + o.getClass() + " element into collection with element type "
                        + type);
            }
        }

        @Override
        public int size() {
            return list.size();
        }

        @Override
        public boolean isEmpty() {
            return list.isEmpty();
        }

        @Override
        public boolean contains(Object o) {
            return list.contains(o);
        }

        @Override
        public Object[] toArray() {
            return list.toArray();
        }

        @Override
        public <T> T[] toArray(T[] a) {
            return list.toArray(a);
        }

        @Override
        public String toString() {
            return list.toString();
        }

        @Override
        public boolean remove(Object o) {
            return list.remove(o);
        }

        @Override
        public boolean containsAll(Collection<?> coll) {
            return list.containsAll(coll);
        }

        @Override
        public boolean removeAll(Collection<?> coll) {
            return list.removeAll(coll);
        }

        @Override
        public boolean retainAll(Collection<?> coll) {
            return list.retainAll(coll);
        }

        @Override
        public boolean removeAll(T... elements) {
            return list.removeAll(elements);
        }

        @Override
        public boolean retainAll(T... elements) {
            return list.retainAll(elements);
        }

        @Override
        public void remove(int from, int to) {
            list.remove(from, to);
        }

        @Override
        public void clear() {
            list.clear();
        }

        @Override
        public boolean equals(Object o) {
            return o == this || list.equals(o);
        }

        @Override
        public int hashCode() {
            return list.hashCode();
        }

        @Override
        public T get(int index) {
            return list.get(index);
        }

        @Override
        public T remove(int index) {
            return list.remove(index);
        }

        @Override
        public int indexOf(Object o) {
            return list.indexOf(o);
        }

        @Override
        public int lastIndexOf(Object o) {
            return list.lastIndexOf(o);
        }

        @Override
        public T set(int index, T element) {
            typeCheck(element);
            return list.set(index, element);
        }

        @Override
        public void add(int index, T element) {
            typeCheck(element);
            list.add(index, element);
        }

        @Override
        @SuppressWarnings("unchecked")
        public boolean addAll(int index, Collection<? extends T> c) {
            T[] a = null;
            try {
                a = c.toArray((T[]) Array.newInstance(type, 0));
            } catch (ArrayStoreException e) {
                throw new ClassCastException();
            }

            return this.list.addAll(index, Arrays.asList(a));
        }

        @Override
        @SuppressWarnings("unchecked")
        public boolean addAll(Collection<? extends T> coll) {
            T[] a = null;
            try {
                a = coll.toArray((T[]) Array.newInstance(type, 0));
            } catch (ArrayStoreException e) {
                throw new ClassCastException();
            }

            return this.list.addAll(Arrays.asList(a));
        }

        @Override
        public ListIterator<T> listIterator() {
            return listIterator(0);
        }

        @Override
        public ListIterator<T> listIterator(final int index) {
            return new ListIterator<T>() {

                ListIterator<T> i = list.listIterator(index);

                @Override
                public boolean hasNext() {
                    return i.hasNext();
                }

                @Override
                public T next() {
                    return i.next();
                }

                @Override
                public boolean hasPrevious() {
                    return i.hasPrevious();
                }

                @Override
                public T previous() {
                    return i.previous();
                }

                @Override
                public int nextIndex() {
                    return i.nextIndex();
                }

                @Override
                public int previousIndex() {
                    return i.previousIndex();
                }

                @Override
                public void remove() {
                    i.remove();
                }

                @Override
                public void set(T e) {
                    typeCheck(e);
                    i.set(e);
                }

                @Override
                public void add(T e) {
                    typeCheck(e);
                    i.add(e);
                }
            };
        }

        @Override
        public Iterator<T> iterator() {
            return new Iterator<T>() {

                private final Iterator<T> it = list.iterator();

                @Override
                public boolean hasNext() {
                    return it.hasNext();
                }

                @Override
                public T next() {
                    return it.next();
                }

                @Override
                public void remove() {
                    it.remove();
                }
            };
        }

        @Override
        public boolean add(T e) {
            typeCheck(e);
            return list.add(e);
        }

        @Override
        public List<T> subList(int fromIndex, int toIndex) {
            return Collections.checkedList(list.subList(fromIndex, toIndex), type);
        }

        @Override
        @SuppressWarnings("unchecked")
        public boolean addAll(T... elements) {
            try {
                T[] array = (T[]) Array.newInstance(type, elements.length);
                System.arraycopy(elements, 0, array, 0, elements.length);
                return list.addAll(array);
            } catch (ArrayStoreException e) {
                throw new ClassCastException();
            }
        }

        @Override
        @SuppressWarnings("unchecked")
        public boolean setAll(T... elements) {
            try {
                T[] array = (T[]) Array.newInstance(type, elements.length);
                System.arraycopy(elements, 0, array, 0, elements.length);
                return list.setAll(array);
            } catch (ArrayStoreException e) {
                throw new ClassCastException();
            }
        }

        @Override
        @SuppressWarnings("unchecked")
        public boolean setAll(Collection<? extends T> col) {
            T[] a = null;
            try {
                a = col.toArray((T[]) Array.newInstance(type, 0));
            } catch (ArrayStoreException e) {
                throw new ClassCastException();
            }

            return list.setAll(Arrays.asList(a));
        }
    }

    private static class EmptyObservableSet<E> extends AbstractSet<E> implements ObservableSet<E> {

        public EmptyObservableSet() {
        }

        @Override
        public void addListener(InvalidationListener listener) {
        }

        @Override
        public void removeListener(InvalidationListener listener) {
        }

        @Override
        public void addListener(SetChangeListener<? super E> listener) {
        }

        @Override
        public void removeListener(SetChangeListener<? super E> listener) {
        }

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

        @Override
        public boolean isEmpty() {
            return true;
        }

        @Override
        public boolean contains(Object obj) {
            return false;
        }

        @Override
        public boolean containsAll(Collection<?> c) {
            return c.isEmpty();
        }

        @Override
        public Object[] toArray() {
            return new Object[0];
        }

        @Override
        public <E> E[] toArray(E[] a) {
            if (a.length > 0)
                a[0] = null;
            return a;
        }

        @Override
        public Iterator<E> iterator() {
            return new Iterator() {

                @Override
                public boolean hasNext() {
                    return false;
                }

                @Override
                public Object next() {
                    throw new NoSuchElementException();
                }

                @Override
                public void remove() {
                    throw new UnsupportedOperationException();
                }
            };
        }

    }

    private static class UnmodifiableObservableSet<E> extends AbstractSet<E> implements ObservableSet<E> {

        private final ObservableSet<E> backingSet;
        private SetListenerHelper<E> listenerHelper;
        private SetChangeListener<E> listener;

        public UnmodifiableObservableSet(ObservableSet<E> backingSet) {
            this.backingSet = backingSet;
            this.listener = null;
        }

        private void initListener() {
            if (listener == null) {
                listener = c -> {
                    callObservers(new SetAdapterChange<E>(UnmodifiableObservableSet.this, c));
                };
                this.backingSet.addListener(new WeakSetChangeListener<E>(listener));
            }
        }

        private void callObservers(SetChangeListener.Change<? extends E> change) {
            SetListenerHelper.fireValueChangedEvent(listenerHelper, change);
        }

        @Override
        public Iterator<E> iterator() {
            return new Iterator<E>() {
                private final Iterator<? extends E> i = backingSet.iterator();

                @Override
                public boolean hasNext() {
                    return i.hasNext();
                }

                @Override
                public E next() {
                    return i.next();
                }
            };
        }

        @Override
        public int size() {
            return backingSet.size();
        }

        @Override
        public boolean isEmpty() {
            return backingSet.isEmpty();
        }

        @Override
        public boolean contains(Object o) {
            return backingSet.contains(o);
        }

        @Override
        public void addListener(InvalidationListener listener) {
            initListener();
            listenerHelper = SetListenerHelper.addListener(listenerHelper, listener);
        }

        @Override
        public void removeListener(InvalidationListener listener) {
            listenerHelper = SetListenerHelper.removeListener(listenerHelper, listener);
        }

        @Override
        public void addListener(SetChangeListener<? super E> listener) {
            initListener();
            listenerHelper = SetListenerHelper.addListener(listenerHelper, listener);
        }

        @Override
        public void removeListener(SetChangeListener<? super E> listener) {
            listenerHelper = SetListenerHelper.removeListener(listenerHelper, listener);
        }

        @Override
        public boolean add(E e) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean remove(Object o) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean addAll(Collection<? extends E> c) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean retainAll(Collection<?> c) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean removeAll(Collection<?> c) {
            throw new UnsupportedOperationException();
        }

        @Override
        public void clear() {
            throw new UnsupportedOperationException();
        }
    }

    private static class SynchronizedSet<E> implements Set<E> {
        final Object mutex;
        private final Set<E> backingSet;

        SynchronizedSet(Set<E> set, Object mutex) {
            this.backingSet = set;
            this.mutex = mutex;
        }

        SynchronizedSet(Set<E> set) {
            this(set, new Object());
        }

        @Override
        public int size() {
            synchronized(mutex) {
                return backingSet.size();
            }
        }

        @Override
        public boolean isEmpty() {
            synchronized(mutex) {
                return backingSet.isEmpty();
            }
        }

        @Override
        public boolean contains(Object o) {
            synchronized(mutex) {
                return backingSet.contains(o);
            }
        }

        @Override
        public Iterator<E> iterator() {
            return backingSet.iterator();
        }

        @Override
        public Object[] toArray() {
            synchronized(mutex) {
                return backingSet.toArray();
            }
        }

        @Override
        public <E> E[] toArray(E[] a) {
            synchronized(mutex) {
                return backingSet.toArray(a);
            }
        }

        @Override
        public boolean add(E e) {
            synchronized(mutex) {
                return backingSet.add(e);
            }
        }

        @Override
        public boolean remove(Object o) {
            synchronized(mutex) {
                return backingSet.remove(o);
            }
        }

        @Override
        public boolean containsAll(Collection<?> c) {
            synchronized(mutex) {
                return backingSet.containsAll(c);
            }
        }

        @Override
        public boolean addAll(Collection<? extends E> c) {
            synchronized(mutex) {
                return backingSet.addAll(c);
            }
        }

        @Override
        public boolean retainAll(Collection<?> c) {
            synchronized(mutex) {
                return backingSet.retainAll(c);
            }
        }

        @Override
        public boolean removeAll(Collection<?> c) {
            synchronized(mutex) {
                return backingSet.removeAll(c);
            }
        }

        @Override
        public void clear() {
            synchronized(mutex) {
                backingSet.clear();
            }
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) {
                return true;
            }
            synchronized(mutex) {
                return backingSet.equals(o);
            }
        }

        @Override
        public int hashCode() {
            synchronized (mutex) {
                return backingSet.hashCode();
            }
        }
    }

    private static class SynchronizedObservableSet<E> extends SynchronizedSet<E> implements ObservableSet<E> {

        private final ObservableSet<E> backingSet;
        private SetListenerHelper listenerHelper;
        private final SetChangeListener<E> listener;

        SynchronizedObservableSet(ObservableSet<E> set, Object mutex) {
            super(set, mutex);
            backingSet = set;
            listener = c -> {
                SetListenerHelper.fireValueChangedEvent(listenerHelper, new SetAdapterChange<E>(SynchronizedObservableSet.this, c));
            };
            backingSet.addListener(new WeakSetChangeListener<E>(listener));
        }

        SynchronizedObservableSet(ObservableSet<E> set) {
            this(set, new Object());
        }

        @Override
        public void addListener(InvalidationListener listener) {
            synchronized (mutex) {
                listenerHelper = SetListenerHelper.addListener(listenerHelper, listener);
            }
        }

        @Override
        public void removeListener(InvalidationListener listener) {
            synchronized (mutex) {
                listenerHelper = SetListenerHelper.removeListener(listenerHelper, listener);
            }
        }
        @Override
        public void addListener(SetChangeListener<? super E> listener) {
            synchronized (mutex) {
                listenerHelper = SetListenerHelper.addListener(listenerHelper, listener);
            }
        }

        @Override
        public void removeListener(SetChangeListener<? super E> listener) {
            synchronized (mutex) {
                listenerHelper = SetListenerHelper.removeListener(listenerHelper, listener);
            }
        }
    }

    private static class CheckedObservableSet<E> extends AbstractSet<E> implements ObservableSet<E> {

        private final ObservableSet<E> backingSet;
        private final Class<E> type;
        private SetListenerHelper listenerHelper;
        private final SetChangeListener<E> listener;

        CheckedObservableSet(ObservableSet<E> set, Class<E> type) {
            if (set == null || type == null) {
                throw new NullPointerException();
            }
            backingSet = set;
            this.type = type;
            listener = c -> {
                callObservers(new SetAdapterChange<E>(CheckedObservableSet.this, c));
            };
            backingSet.addListener(new WeakSetChangeListener<E>(listener));
        }

        private void callObservers(SetChangeListener.Change<? extends E> c) {
            SetListenerHelper.fireValueChangedEvent(listenerHelper, c);
        }

        void typeCheck(Object o) {
            if (o != null && !type.isInstance(o)) {
                throw new ClassCastException("Attempt to insert "
                        + o.getClass() + " element into collection with element type "
                        + type);
            }
        }

        @Override
        public void addListener(InvalidationListener listener) {
            listenerHelper = SetListenerHelper.addListener(listenerHelper, listener);
        }

        @Override
        public void removeListener(InvalidationListener listener) {
            listenerHelper = SetListenerHelper.removeListener(listenerHelper, listener);
        }

        @Override
        public void addListener(SetChangeListener<? super E> listener) {
            listenerHelper = SetListenerHelper.addListener(listenerHelper, listener);
        }

        @Override
        public void removeListener(SetChangeListener<? super E> listener) {
            listenerHelper = SetListenerHelper.removeListener(listenerHelper, listener);
        }

        @Override
        public int size() {
            return backingSet.size();
        }

        @Override
        public boolean isEmpty() {
            return backingSet.isEmpty();
        }

        @Override
        public boolean contains(Object o) {
            return backingSet.contains(o);
        }

        @Override
        public Object[] toArray() {
            return backingSet.toArray();
        }

        @Override
        public <T> T[] toArray(T[] a) {
            return backingSet.toArray(a);
        }

        @Override
        public boolean add(E e) {
            typeCheck(e);
            return backingSet.add(e);
        }

        @Override
        public boolean remove(Object o) {
            return backingSet.remove(o);
        }

        @Override
        public boolean containsAll(Collection<?> c) {
            return backingSet.containsAll(c);
        }

        @Override
        @SuppressWarnings("unchecked")
        public boolean addAll(Collection<? extends E> c) {
            E[] a = null;
            try {
                a = c.toArray((E[]) Array.newInstance(type, 0));
            } catch (ArrayStoreException e) {
                throw new ClassCastException();
            }

            return backingSet.addAll(Arrays.asList(a));
        }

        @Override
        public boolean retainAll(Collection<?> c) {
            return backingSet.retainAll(c);
        }

        @Override
        public boolean removeAll(Collection<?> c) {
            return backingSet.removeAll(c);
        }

        @Override
        public void clear() {
            backingSet.clear();
        }

        @Override
        public boolean equals(Object o) {
            return o == this || backingSet.equals(o);
        }

        @Override
        public int hashCode() {
            return backingSet.hashCode();
        }

        @Override
        public Iterator<E> iterator() {
            final Iterator<E> it = backingSet.iterator();

            return new Iterator<E>() {
                @Override
                public boolean hasNext() {
                    return it.hasNext();
                }

                @Override
                public E next() {
                    return it.next();
                }

                @Override
                public void remove() {
                    it.remove();
                }
            };
        }

    }

    private static class EmptyObservableMap<K, V> extends AbstractMap<K, V> implements ObservableMap<K, V> {

        public EmptyObservableMap() {
        }

        @Override
        public void addListener(InvalidationListener listener) {
        }

        @Override
        public void removeListener(InvalidationListener listener) {
        }

        @Override
        public void addListener(MapChangeListener<? super K, ? super V> listener) {
        }

        @Override
        public void removeListener(MapChangeListener<? super K, ? super V> listener) {
        }

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

        @Override
        public boolean isEmpty() {
            return true;
        }

        @Override
        public boolean containsKey(Object key) {
            return false;
        }

        @Override
        public boolean containsValue(Object value) {
            return false;
        }

        @Override
        public V get(Object key) {
            return null;
        }

        @Override
        public Set<K> keySet() {
            return emptyObservableSet();
        }

        @Override
        public Collection<V> values() {
            return emptyObservableSet();
        }

        @Override
        public Set<Map.Entry<K,V>> entrySet() {
            return emptyObservableSet();
        }

        @Override
        public boolean equals(Object o) {
            return (o instanceof Map) && ((Map<?,?>)o).isEmpty();
        }

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

    private static class CheckedObservableMap<K, V> extends AbstractMap<K, V> implements ObservableMap<K, V> {

        private final ObservableMap<K, V> backingMap;
        private final Class<K> keyType;
        private final Class<V> valueType;
        private MapListenerHelper listenerHelper;
        private final MapChangeListener<K, V> listener;

        CheckedObservableMap(ObservableMap<K, V> map, Class<K> keyType, Class<V> valueType) {
            backingMap = map;
            this.keyType = keyType;
            this.valueType = valueType;
            listener = c -> {
                callObservers(new MapAdapterChange<K, V>(CheckedObservableMap.this, c));
            };
            backingMap.addListener(new WeakMapChangeListener<K, V>(listener));
        }

        private void callObservers(MapChangeListener.Change<? extends K, ? extends V> c) {
            MapListenerHelper.fireValueChangedEvent(listenerHelper, c);
        }

        void typeCheck(Object key, Object value) {
            if (key != null && !keyType.isInstance(key)) {
                throw new ClassCastException("Attempt to insert "
                        + key.getClass() + " key into map with key type "
                        + keyType);
            }

            if (value != null && !valueType.isInstance(value)) {
                throw new ClassCastException("Attempt to insert "
                        + value.getClass() + " value into map with value type "
                        + valueType);
            }
        }

        @Override
        public void addListener(InvalidationListener listener) {
            listenerHelper = MapListenerHelper.addListener(listenerHelper, listener);
        }

        @Override
        public void removeListener(InvalidationListener listener) {
            listenerHelper = MapListenerHelper.removeListener(listenerHelper, listener);
        }

        @Override
        public void addListener(MapChangeListener<? super K, ? super V> listener) {
            listenerHelper = MapListenerHelper.addListener(listenerHelper, listener);
        }

        @Override
        public void removeListener(MapChangeListener<? super K, ? super V> listener) {
            listenerHelper = MapListenerHelper.removeListener(listenerHelper, listener);
        }

        @Override
        public int size() {
            return backingMap.size();
        }

        @Override
        public boolean isEmpty() {
            return backingMap.isEmpty();
        }

        @Override
        public boolean containsKey(Object key) {
            return backingMap.containsKey(key);
        }

        @Override
        public boolean containsValue(Object value) {
            return backingMap.containsValue(value);
        }

        @Override
        public V get(Object key) {
            return backingMap.get(key);
        }

        @Override
        public V put(K key, V value) {
            typeCheck(key, value);
            return backingMap.put(key, value);
        }

        @Override
        public V remove(Object key) {
            return backingMap.remove(key);
        }

        @Override
        @SuppressWarnings("unchecked")
        public void putAll(Map t) {
            // Satisfy the following goals:
            // - good diagnostics in case of type mismatch
            // - all-or-nothing semantics
            // - protection from malicious t
            // - correct behavior if t is a concurrent map
            Object[] entries = t.entrySet().toArray();
            List<Map.Entry<K,V>> checked =
                new ArrayList<Map.Entry<K,V>>(entries.length);
            for (Object o : entries) {
                Map.Entry<?,?> e = (Map.Entry<?,?>) o;
                Object k = e.getKey();
                Object v = e.getValue();
                typeCheck(k, v);
                checked.add(
                    new AbstractMap.SimpleImmutableEntry<K,V>((K) k, (V) v));
            }
            for (Map.Entry<K,V> e : checked)
                backingMap.put(e.getKey(), e.getValue());
        }

        @Override
        public void clear() {
            backingMap.clear();
        }

        @Override
        public Set<K> keySet() {
            return backingMap.keySet();
        }

        @Override
        public Collection<V> values() {
            return backingMap.values();
        }

        private transient Set<Map.Entry<K,V>> entrySet = null;

        @Override
        public Set entrySet() {
            if (entrySet==null)
                entrySet = new CheckedEntrySet<K,V>(backingMap.entrySet(), valueType);
            return entrySet;
        }

        @Override
        public boolean equals(Object o) {
            return o == this || backingMap.equals(o);
        }

        @Override
        public int hashCode() {
            return backingMap.hashCode();
        }

        static class CheckedEntrySet<K,V> implements Set<Map.Entry<K,V>> {
            private final Set<Map.Entry<K,V>> s;
            private final Class<V> valueType;

            CheckedEntrySet(Set<Map.Entry<K, V>> s, Class<V> valueType) {
                this.s = s;
                this.valueType = valueType;
            }

            @Override
            public int size() {
                return s.size();
            }

            @Override
            public boolean isEmpty() {
                return s.isEmpty();
            }

            @Override
            public String toString() {
                return s.toString();
            }

            @Override
            public int hashCode() {
                return s.hashCode();
            }

            @Override
            public void clear() {
                s.clear();
            }

            @Override
            public boolean add(Map.Entry<K, V> e) {
                throw new UnsupportedOperationException();
            }

            @Override
            public boolean addAll(Collection<? extends Map.Entry<K, V>> coll) {
                throw new UnsupportedOperationException();
            }

            @Override
            public Iterator<Map.Entry<K,V>> iterator() {
                final Iterator<Map.Entry<K, V>> i = s.iterator();
                final Class<V> valueType = this.valueType;

                return new Iterator<Map.Entry<K,V>>() {
                    @Override
                    public boolean hasNext() {
                        return i.hasNext();
                    }

                    @Override
                    public void remove() {
                        i.remove();
                    }

                    @Override
                    public Map.Entry<K,V> next() {
                        return checkedEntry(i.next(), valueType);
                    }
                };
            }

            @Override
            @SuppressWarnings("unchecked")
            public Object[] toArray() {
                Object[] source = s.toArray();

                /*
                 * Ensure that we don't get an ArrayStoreException even if
                 * s.toArray returns an array of something other than Object
                 */
                Object[] dest = (CheckedEntry.class.isInstance(
                    source.getClass().getComponentType()) ? source :
                                 new Object[source.length]);

                for (int i = 0; i < source.length; i++)
                    dest[i] = checkedEntry((Map.Entry<K,V>)source[i],
                                           valueType);
                return dest;
            }

            @Override
            @SuppressWarnings("unchecked")
            public <T> T[] toArray(T[] a) {
                // We don't pass a to s.toArray, to avoid window of
                // vulnerability wherein an unscrupulous multithreaded client
                // could get his hands on raw (unwrapped) Entries from s.
                T[] arr = s.toArray(a.length==0 ? a : Arrays.copyOf(a, 0));

                for (int i=0; i<arr.length; i++)
                    arr[i] = (T) checkedEntry((Map.Entry<K,V>)arr[i],
                                              valueType);
                if (arr.length > a.length)
                    return arr;

                System.arraycopy(arr, 0, a, 0, arr.length);
                if (a.length > arr.length)
                    a[arr.length] = null;
                return a;
            }

            
This method is overridden to protect the backing set against
an object with a nefarious equals function that senses
that the equality-candidate is Map.Entry and calls its
setValue method.
/**
             * This method is overridden to protect the backing set against
             * an object with a nefarious equals function that senses
             * that the equality-candidate is Map.Entry and calls its
             * setValue method.
             */
            @Override
            public boolean contains(Object o) {
                if (!(o instanceof Map.Entry))
                    return false;
                Map.Entry<?,?> e = (Map.Entry<?,?>) o;
                return s.contains(
                    (e instanceof CheckedEntry) ? e : checkedEntry(e, valueType));
            }

            
The bulk collection methods are overridden to protect
against an unscrupulous collection whose contains(Object o)
method senses when o is a Map.Entry, and calls o.setValue.
/**
             * The bulk collection methods are overridden to protect
             * against an unscrupulous collection whose contains(Object o)
             * method senses when o is a Map.Entry, and calls o.setValue.
             */
            @Override
            public boolean containsAll(Collection<?> c) {
                for (Object o : c)
                    if (!contains(o)) // Invokes safe contains() above
                        return false;
                return true;
            }

            @Override
            public boolean remove(Object o) {
                if (!(o instanceof Map.Entry))
                    return false;
                return s.remove(new AbstractMap.SimpleImmutableEntry
                                <Object, Object>((Map.Entry<?,?>)o));
            }

            @Override
            public boolean removeAll(Collection<?> c) {
                return batchRemove(c, false);
            }

            @Override
            public boolean retainAll(Collection<?> c) {
                return batchRemove(c, true);
            }

            private boolean batchRemove(Collection<?> c, boolean complement) {
                boolean modified = false;
                Iterator<Map.Entry<K,V>> it = iterator();
                while (it.hasNext()) {
                    if (c.contains(it.next()) != complement) {
                        it.remove();
                        modified = true;
                    }
                }
                return modified;
            }

            @Override
            public boolean equals(Object o) {
                if (o == this)
                    return true;
                if (!(o instanceof Set))
                    return false;
                Set<?> that = (Set<?>) o;
                return that.size() == s.size()
                    && containsAll(that); // Invokes safe containsAll() above
            }

            static <K,V,T> CheckedEntry<K,V,T> checkedEntry(Map.Entry<K,V> e,
                                                            Class<T> valueType) {
                return new CheckedEntry<K,V,T>(e, valueType);
            }

            
This "wrapper class" serves two purposes: it prevents
the client from modifying the backing Map, by short-circuiting
the setValue method, and it protects the backing Map against
an ill-behaved Map.Entry that attempts to modify another
Map.Entry when asked to perform an equality check.
/**
             * This "wrapper class" serves two purposes: it prevents
             * the client from modifying the backing Map, by short-circuiting
             * the setValue method, and it protects the backing Map against
             * an ill-behaved Map.Entry that attempts to modify another
             * Map.Entry when asked to perform an equality check.
             */
            private static class CheckedEntry<K,V,T> implements Map.Entry<K,V> {
                private final Map.Entry<K, V> e;
                private final Class<T> valueType;

                CheckedEntry(Map.Entry<K, V> e, Class<T> valueType) {
                    this.e = e;
                    this.valueType = valueType;
                }

                @Override
                public K getKey() {
                    return e.getKey();
                }

                @Override
                public V getValue() {
                    return e.getValue();
                }

                @Override
                public int hashCode() {
                    return e.hashCode();
                }

                @Override
                public String toString() {
                    return e.toString();
                }

                @Override
                public V setValue(V value) {
                    if (value != null && !valueType.isInstance(value))
                        throw new ClassCastException(badValueMsg(value));
                    return e.setValue(value);
                }

                private String badValueMsg(Object value) {
                    return "Attempt to insert " + value.getClass() +
                        " value into map with value type " + valueType;
                }

                @Override
                public boolean equals(Object o) {
                    if (o == this)
                        return true;
                    if (!(o instanceof Map.Entry))
                        return false;
                    return e.equals(new AbstractMap.SimpleImmutableEntry
                                    <Object, Object>((Map.Entry<?,?>)o));
                }
            }
        }

    }

    private static class SynchronizedMap<K, V> implements Map<K, V> {
        final Object mutex;
        private final Map<K, V> backingMap;

        SynchronizedMap(Map<K, V> map, Object mutex) {
            backingMap = map;
            this.mutex = mutex;
        }

        SynchronizedMap(Map<K, V> map) {
            this(map, new Object());
        }

        @Override
        public int size() {
            synchronized (mutex) {
                return backingMap.size();
            }
        }

        @Override
        public boolean isEmpty() {
            synchronized (mutex) {
                return backingMap.isEmpty();
            }
        }

        @Override
        public boolean containsKey(Object key) {
            synchronized (mutex) {
                return backingMap.containsKey(key);
            }
        }

        @Override
        public boolean containsValue(Object value) {
            synchronized (mutex) {
                return backingMap.containsValue(value);
            }
        }

        @Override
        public V get(Object key) {
            synchronized (mutex) {
                return backingMap.get(key);
            }
        }

        @Override
        public V put(K key, V value) {
            synchronized (mutex) {
                return backingMap.put(key, value);
            }
        }

        @Override
        public V remove(Object key) {
            synchronized (mutex) {
                return backingMap.remove(key);
            }
        }

        @Override
        public void putAll(Map<? extends K, ? extends V> m) {
            synchronized (mutex) {
                backingMap.putAll(m);
            }
        }

        @Override
        public void clear() {
            synchronized (mutex) {
                backingMap.clear();
            }
        }

        private transient Set<K> keySet = null;
        private transient Set<Map.Entry<K,V>> entrySet = null;
        private transient Collection<V> values = null;

        @Override
        public Set<K> keySet() {
            synchronized(mutex) {
                if (keySet==null)
                    keySet = new SynchronizedSet<K>(backingMap.keySet(), mutex);
                return keySet;
            }
        }

        @Override
        public Collection<V> values() {
            synchronized(mutex) {
                if (values==null)
                    values = new SynchronizedCollection<V>(backingMap.values(), mutex);
                return values;
            }
        }

        @Override
        public Set<Entry<K, V>> entrySet() {
            synchronized(mutex) {
                if (entrySet==null)
                    entrySet = new SynchronizedSet<Map.Entry<K,V>>(backingMap.entrySet(), mutex);
                return entrySet;
            }
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) {
                return true;
            }
            synchronized(mutex) {
                return backingMap.equals(o);
            }
        }

        @Override
        public int hashCode() {
            synchronized(mutex) {
                return backingMap.hashCode();
            }
        }

    }

    private static class SynchronizedCollection<E> implements Collection<E> {

        private final Collection<E> backingCollection;
        final Object mutex;

        SynchronizedCollection(Collection<E> c, Object mutex) {
            backingCollection = c;
            this.mutex = mutex;
        }

        SynchronizedCollection(Collection<E> c) {
            this(c, new Object());
        }

        @Override
        public int size() {
            synchronized (mutex) {
                return backingCollection.size();
            }
        }

        @Override
        public boolean isEmpty() {
            synchronized (mutex) {
                return backingCollection.isEmpty();
            }
        }

        @Override
        public boolean contains(Object o) {
            synchronized (mutex) {
                return backingCollection.contains(o);
            }
        }

        @Override
        public Iterator<E> iterator() {
            return backingCollection.iterator();
        }

        @Override
        public Object[] toArray() {
            synchronized (mutex) {
                return backingCollection.toArray();
            }
        }

        @Override
        public <T> T[] toArray(T[] a) {
            synchronized (mutex) {
                return backingCollection.toArray(a);
            }
        }

        @Override
        public boolean add(E e) {
            synchronized (mutex) {
                return backingCollection.add(e);
            }
        }

        @Override
        public boolean remove(Object o) {
            synchronized (mutex) {
                return backingCollection.remove(o);
            }
        }

        @Override
        public boolean containsAll(Collection<?> c) {
            synchronized (mutex) {
                return backingCollection.containsAll(c);
            }
        }

        @Override
        public boolean addAll(Collection<? extends E> c) {
            synchronized (mutex) {
                return backingCollection.addAll(c);
            }
        }

        @Override
        public boolean removeAll(Collection<?> c) {
            synchronized (mutex) {
                return backingCollection.removeAll(c);
            }
        }

        @Override
        public boolean retainAll(Collection<?> c) {
            synchronized (mutex) {
                return backingCollection.retainAll(c);
            }
        }

        @Override
        public void clear() {
            synchronized (mutex) {
                backingCollection.clear();
            }
        }
    }

    private static class SynchronizedObservableMap<K, V> extends SynchronizedMap<K, V> implements ObservableMap<K, V> {

        private final ObservableMap<K, V> backingMap;
        private MapListenerHelper listenerHelper;
        private final MapChangeListener<K, V> listener;

        SynchronizedObservableMap(ObservableMap<K, V> map, Object mutex) {
            super(map, mutex);
            backingMap = map;
            listener = c -> {
                MapListenerHelper.fireValueChangedEvent(listenerHelper, new MapAdapterChange<K, V>(SynchronizedObservableMap.this, c));
            };
            backingMap.addListener(new WeakMapChangeListener<K, V>(listener));
        }

        SynchronizedObservableMap(ObservableMap<K, V> map) {
            this(map, new Object());
        }

        @Override
        public void addListener(InvalidationListener listener) {
            synchronized (mutex) {
                listenerHelper = MapListenerHelper.addListener(listenerHelper, listener);
            }
        }

        @Override
        public void removeListener(InvalidationListener listener) {
            synchronized (mutex) {
                listenerHelper = MapListenerHelper.removeListener(listenerHelper, listener);
            }
        }

        @Override
        public void addListener(MapChangeListener<? super K, ? super V> listener) {
            synchronized (mutex) {
                listenerHelper = MapListenerHelper.addListener(listenerHelper, listener);
            }
        }

        @Override
        public void removeListener(MapChangeListener<? super K, ? super V> listener) {
            synchronized (mutex) {
                listenerHelper = MapListenerHelper.removeListener(listenerHelper, listener);
            }
        }

    }

}