com.google.common.collect

Class ForwardingMapEntry<K,V>

java.lang.Object

com.google.common.collect.ForwardingObject

com.google.common.collect.ForwardingMapEntry<K,V>

All Implemented Interfaces:

Map.Entry<K,V>

@GwtCompatible
public abstract class ForwardingMapEntry<K,V>
extends ForwardingObject
implements Map.Entry<K,V>

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

Warning: The methods of ForwardingMapEntry forward indiscriminately to the methods of the delegate. For example, overriding getValue() alone will not change the behavior of equals(java.lang.Object), which can lead to unexpected behavior. In this case, you should override equals as well, either providing your own implementation, or delegating to the provided standardEquals 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 the entry of a SortedMap whose comparator is not consistent with equals.

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

Since:

2.0

Author:

Mike Bostock, Louis Wasserman

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ForwardingMapEntry() Constructor for use by subclasses.

Method Summary

Modifier and Type	Method and Description
protected abstract Map.Entry<K,V>	delegate() Returns the backing delegate instance that methods are forwarded to.
boolean	equals(Object object)
K	getKey()
V	getValue()
int	hashCode()
V	setValue(V value)
protected boolean	standardEquals(Object object) A sensible definition of equals(Object) in terms of getKey() and getValue().
protected int	standardHashCode() A sensible definition of hashCode() in terms of getKey() and getValue().
protected String	standardToString() A sensible definition of ForwardingObject.toString() in terms of getKey() and getValue().

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

Methods inherited from interface java.util.Map.Entry

comparingByKey, comparingByKey, comparingByValue, comparingByValue

Constructor Detail

ForwardingMapEntry

protected ForwardingMapEntry()

Constructor for use by subclasses.

Method Detail

delegate

protected abstract Map.Entry<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

getKey

public K getKey()

Specified by:

getKey in interface Map.Entry<K,V>

getValue

public V getValue()

Specified by:

getValue in interface Map.Entry<K,V>

setValue

public V setValue(V value)

Specified by:

setValue in interface Map.Entry<K,V>

equals

public boolean equals(@Nullable
                      Object object)

Specified by:

equals in interface Map.Entry<K,V>

Overrides:

equals in class Object

hashCode

public int hashCode()

Specified by:

hashCode in interface Map.Entry<K,V>

Overrides:

hashCode in class Object

standardEquals

protected boolean standardEquals(@Nullable
                                 Object object)

A sensible definition of equals(Object) in terms of getKey() and getValue(). If you override either of these methods, you may wish to override equals(Object) to forward to this implementation.

Since:

7.0

standardHashCode

protected int standardHashCode()

A sensible definition of hashCode() in terms of getKey() and getValue(). If you override either of these methods, you may wish to override hashCode() to forward to this implementation.

Since:

7.0

standardToString

@Beta
protected String standardToString()

A sensible definition of ForwardingObject.toString() in terms of getKey() and getValue(). If you override either of these methods, you may wish to override equals(java.lang.Object) to forward to this implementation.

Since:

7.0