Class ForwardingMapEntry<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
- java.lang.Object
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- com.google.common.collect.ForwardingObject
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- com.google.common.collect.ForwardingMapEntry<K,V>
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- All Implemented Interfaces:
java.util.Map.Entry<K,V>
@GwtCompatible public abstract class ForwardingMapEntry<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object> extends ForwardingObject implements java.util.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, overridinggetValue()
alone will not change the behavior ofequals(java.lang.Object)
, which can lead to unexpected behavior. In this case, you should overrideequals
as well, either providing your own implementation, or delegating to the providedstandardEquals
method.Each of the
standard
methods, where appropriate, useObjects.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 aSortedMap
whose comparator is not consistent withequals
.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
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Constructor Summary
Constructors Modifier Constructor Description protected
ForwardingMapEntry()
Constructor for use by subclasses.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected abstract java.util.Map.Entry<K,V>
delegate()
Returns the backing delegate instance that methods are forwarded to.boolean
equals(java.lang.Object object)
K
getKey()
V
getValue()
int
hashCode()
V
setValue(V value)
protected boolean
standardEquals(java.lang.Object object)
protected int
standardHashCode()
protected java.lang.String
standardToString()
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Methods inherited from class com.google.common.collect.ForwardingObject
toString
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Constructor Detail
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ForwardingMapEntry
protected ForwardingMapEntry()
Constructor for use by subclasses.
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Method Detail
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delegate
protected abstract java.util.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 asForwardingSet.delegate()
. Concrete subclasses override this method to supply the instance being decorated.- Specified by:
delegate
in classForwardingObject
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equals
public boolean equals(@CheckForNull java.lang.Object object)
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hashCode
public int hashCode()
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standardEquals
protected boolean standardEquals(@CheckForNull java.lang.Object object)
A sensible definition ofequals(Object)
in terms ofgetKey()
andgetValue()
. If you override either of these methods, you may wish to overrideequals(Object)
to forward to this implementation.- Since:
- 7.0
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standardHashCode
protected int standardHashCode()
A sensible definition ofhashCode()
in terms ofgetKey()
andgetValue()
. If you override either of these methods, you may wish to overridehashCode()
to forward to this implementation.- Since:
- 7.0
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standardToString
protected java.lang.String standardToString()
A sensible definition ofForwardingObject.toString()
in terms ofgetKey()
andgetValue()
. If you override either of these methods, you may wish to overrideequals(java.lang.Object)
to forward to this implementation.- Since:
- 7.0
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