com.google.common.collect
Class ForwardingMap<K,V>

java.lang.Object
  com.google.common.collect.ForwardingObject
      com.google.common.collect.ForwardingMap<K,V>

All Implemented Interfaces:

java.util.Map<K,V>

Direct Known Subclasses:

EnumBiMap, EnumHashBiMap, ForwardingConcurrentMap, ForwardingSortedMap, HashBiMap, ImmutableClassToInstanceMap, MutableClassToInstanceMap

@GwtCompatible
public abstract class ForwardingMap<K,V>
extends ForwardingObject
implements java.util.Map<K,V>

A map which forwards all its method calls to another map. Subclasses should override one or more methods to modify the behavior of the backing map as desired per the decorator pattern.

Warning: The methods of ForwardingMap forward indiscriminately to the methods of the delegate. For example, overriding put(K, V) alone will not change the behavior of putAll(java.util.Map), which can lead to unexpected behavior. In this case, you should override putAll as well, either providing your own implementation, or delegating to the provided standardPutAll method.

Each of the standard methods, where appropriate, use Objects.equal(java.lang.Object, java.lang.Object) to test equality for both keys and values. This may not be the desired behavior for map implementations that use non-standard notions of key equality, such as a SortedMap whose comparator is not consistent with equals.

The standard methods and the collection views they return are not guaranteed to be thread-safe, even when all of the methods that they depend on are thread-safe.

Since:

2.0 (imported from Google Collections Library)

Nested Class Summary

protected class	ForwardingMap.StandardEntrySet A sensible implementation of Map.entrySet() in terms of the following methods: clear(), containsKey(java.lang.Object), get(java.lang.Object), isEmpty(), remove(java.lang.Object), and size().
protected class	ForwardingMap.StandardKeySet A sensible implementation of Map.keySet() in terms of the following methods: clear(), containsKey(java.lang.Object), isEmpty(), remove(java.lang.Object), size(), and the Set.iterator() method of entrySet().
protected class	ForwardingMap.StandardValues A sensible implementation of Map.values() in terms of the following methods: clear(), containsValue(java.lang.Object), isEmpty(), size(), and the Set.iterator() method of entrySet().

Nested classes/interfaces inherited from interface java.util.Map

java.util.Map.Entry<K,V>

Constructor Summary

protected

ForwardingMap() Constructor for use by subclasses.

Method Summary

void	clear()
boolean	containsKey(java.lang.Object key)
boolean	containsValue(java.lang.Object value)
protected abstract java.util.Map<K,V>	delegate() Returns the backing delegate instance that methods are forwarded to.
java.util.Set<java.util.Map.Entry<K,V>>	entrySet()
boolean	equals(java.lang.Object object)
V	get(java.lang.Object key)
int	hashCode()
boolean	isEmpty()
java.util.Set<K>	keySet()
V	put(K key, V value)
void	putAll(java.util.Map<? extends K,? extends V> map)
V	remove(java.lang.Object object)
int	size()
protected void	standardClear() A sensible definition of clear() in terms of the iterator method of entrySet().
protected boolean	standardContainsKey(java.lang.Object key) A sensible, albeit inefficient, definition of containsKey(java.lang.Object) in terms of the iterator method of entrySet().
protected boolean	standardContainsValue(java.lang.Object value) A sensible definition of containsValue(java.lang.Object) in terms of the iterator method of entrySet().
protected boolean	standardEquals(java.lang.Object object) A sensible definition of equals(java.lang.Object) in terms of the equals method of entrySet().
protected int	standardHashCode() A sensible definition of hashCode() in terms of the iterator method of entrySet().
protected boolean	standardIsEmpty() A sensible definition of isEmpty() in terms of the iterator method of entrySet().
protected void	standardPutAll(java.util.Map<? extends K,? extends V> map) A sensible definition of putAll(Map) in terms of put(Object, Object).
protected V	standardRemove(java.lang.Object key) A sensible, albeit inefficient, definition of remove(java.lang.Object) in terms of the iterator method of entrySet().
protected java.lang.String	standardToString() A sensible definition of ForwardingObject.toString() in terms of the iterator method of entrySet().
java.util.Collection<V>	values()

Methods inherited from class com.google.common.collect.ForwardingObject

toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ForwardingMap

protected ForwardingMap()

Constructor for use by subclasses.

Method Detail

delegate

protected abstract java.util.Map<K,V> delegate()

Description copied from class: ForwardingObject

Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet.delegate(). Concrete subclasses override this method to supply the instance being decorated.

Specified by:

delegate in class ForwardingObject

size

public int size()

Specified by:

size in interface java.util.Map<K,V>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface java.util.Map<K,V>

remove

public V remove(java.lang.Object object)

Specified by:

remove in interface java.util.Map<K,V>

clear

public void clear()

Specified by:

clear in interface java.util.Map<K,V>

containsKey

public boolean containsKey(java.lang.Object key)

Specified by:

containsKey in interface java.util.Map<K,V>

containsValue

public boolean containsValue(java.lang.Object value)

Specified by:

containsValue in interface java.util.Map<K,V>

get

public V get(java.lang.Object key)

Specified by:

get in interface java.util.Map<K,V>

put

public V put(K key,
             V value)

Specified by:

put in interface java.util.Map<K,V>

putAll

public void putAll(java.util.Map<? extends K,? extends V> map)

Specified by:

putAll in interface java.util.Map<K,V>

keySet

public java.util.Set<K> keySet()

Specified by:

keySet in interface java.util.Map<K,V>

values

public java.util.Collection<V> values()

Specified by:

values in interface java.util.Map<K,V>

entrySet

public java.util.Set<java.util.Map.Entry<K,V>> entrySet()

Specified by:

entrySet in interface java.util.Map<K,V>

equals

public boolean equals(@Nullable
                      java.lang.Object object)

Specified by:

equals in interface java.util.Map<K,V>

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Specified by:

hashCode in interface java.util.Map<K,V>

Overrides:

hashCode in class java.lang.Object

standardPutAll

@Beta
protected void standardPutAll(java.util.Map<? extends K,? extends V> map)

A sensible definition of putAll(Map) in terms of put(Object, Object). If you override put(Object, Object), you may wish to override putAll(Map) to forward to this implementation.

Since:

7.0

standardRemove

@Beta
protected V standardRemove(@Nullable
                                java.lang.Object key)

A sensible, albeit inefficient, definition of remove(java.lang.Object) in terms of the iterator method of entrySet(). If you override entrySet(), you may wish to override remove(java.lang.Object) to forward to this implementation.

Alternately, you may wish to override remove(java.lang.Object) with keySet().remove, assuming that approach would not lead to an infinite loop.

Since:

7.0

standardClear

@Beta
protected void standardClear()

A sensible definition of clear() in terms of the iterator method of entrySet(). In many cases, you may wish to override clear() to forward to this implementation.

Since:

7.0

standardContainsKey

@Beta
protected boolean standardContainsKey(@Nullable
                                           java.lang.Object key)

A sensible, albeit inefficient, definition of containsKey(java.lang.Object) in terms of the iterator method of entrySet(). If you override entrySet(), you may wish to override containsKey(java.lang.Object) to forward to this implementation.

Since:

7.0

standardContainsValue

@Beta
protected boolean standardContainsValue(@Nullable
                                             java.lang.Object value)

A sensible definition of containsValue(java.lang.Object) in terms of the iterator method of entrySet(). If you override entrySet(), you may wish to override containsValue(java.lang.Object) to forward to this implementation.

Since:

7.0

standardIsEmpty

@Beta
protected boolean standardIsEmpty()

A sensible definition of isEmpty() in terms of the iterator method of entrySet(). If you override entrySet(), you may wish to override isEmpty() to forward to this implementation.

Since:

7.0

standardEquals

@Beta
protected boolean standardEquals(@Nullable
                                      java.lang.Object object)

A sensible definition of equals(java.lang.Object) in terms of the equals method of entrySet(). If you override entrySet(), you may wish to override equals(java.lang.Object) to forward to this implementation.

Since:

7.0

standardHashCode

@Beta
protected int standardHashCode()

A sensible definition of hashCode() in terms of the iterator method of entrySet(). If you override entrySet(), you may wish to override hashCode() to forward to this implementation.

Since:

7.0

standardToString

@Beta
protected java.lang.String standardToString()

A sensible definition of ForwardingObject.toString() in terms of the iterator method of entrySet(). If you override entrySet(), you may wish to override ForwardingObject.toString() to forward to this implementation.

Since:

7.0