public abstract class ForwardingMap<K,V> extends ForwardingObject implements java.util.Map<K,V>
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<? extends K, ? extends V>), 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.
default method warning: This class does not forward calls to default methods. Instead, it inherits their default implementations. When those implementations
invoke methods, they invoke methods on the ForwardingMap.
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.
| Modifier and Type | Class and Description |
|---|---|
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(). |
| Modifier | Constructor and Description |
|---|---|
protected |
ForwardingMap()
Constructor for use by subclasses.
|
| Modifier and Type | Method and Description |
|---|---|
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 key) |
int |
size() |
protected void |
standardClear()
|
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)
|
protected int |
standardHashCode()
|
protected boolean |
standardIsEmpty()
|
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()
|
java.util.Collection<V> |
values() |
toStringprotected abstract java.util.Map<K,V> delegate()
ForwardingObjectForwardingSet.delegate(). Concrete subclasses override this method to supply the
instance being decorated.delegate in class ForwardingObject@CheckForNull public V remove(@CheckForNull java.lang.Object key)
public boolean containsKey(@CheckForNull
java.lang.Object key)
public boolean containsValue(@CheckForNull
java.lang.Object value)
@CheckForNull public V get(@CheckForNull java.lang.Object key)
public boolean equals(@CheckForNull
java.lang.Object object)
public int hashCode()
protected void standardPutAll(java.util.Map<? extends K,? extends V> map)
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.@CheckForNull protected V standardRemove(@CheckForNull java.lang.Object key)
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.
protected void standardClear()
clear() in terms of the iterator method of entrySet(). In many cases, you may wish to override clear() to forward to this
implementation.protected boolean standardContainsKey(@CheckForNull
java.lang.Object key)
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.protected boolean standardContainsValue(@CheckForNull
java.lang.Object value)
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.protected boolean standardIsEmpty()
isEmpty() in terms of the iterator method of entrySet(). If you override entrySet(), you may wish to override isEmpty() to
forward to this implementation.protected boolean standardEquals(@CheckForNull
java.lang.Object object)
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.protected int standardHashCode()
hashCode() in terms of the iterator method of entrySet(). If you override entrySet(), you may wish to override hashCode() to
forward to this implementation.protected java.lang.String standardToString()
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.