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

public static interface java.util

Map.Entry<K, V>

Java SE 6

Contained within: Map

Implemented by: AbstractMap.SimpleEntry, AbstractMap.SimpleImmutableEntry

A map entry (key-value pair). The Map.entrySet method returns a collection-view of the map, whose elements are of this class. The only way to obtain a reference to a map entry is from the iterator of this collection-view. These Map.Entry objects are valid only for the duration of the iteration; more formally, the behavior of a map entry is undefined if the backing map has been modified after the entry was returned by the iterator, except through the setValue operation on the map entry.

since	1.2
See also	entrySet()

Methods

public boolean

equals(Object o)
Compares the specified object with this entry for equality. Returns true if the given object is also a map entry and the two entries represent the same mapping. More formally, two entries e1 and e2 represent the same mapping if

     (e1.getKey()==null ?
      e2.getKey()==null : e1.getKey().equals(e2.getKey()))  &&
     (e1.getValue()==null ?
      e2.getValue()==null : e1.getValue().equals(e2.getValue()))

This ensures that the equals method works properly across different implementations of the Map.Entry interface.

o	object to be compared for equality with this map entry
return	`true` if the specified object is equal to this map entry

public int

hashCode()
Returns the hash code value for this map entry. The hash code of a map entry e is defined to be:

     (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
     (e.getValue()==null ? 0 : e.getValue().hashCode())

This ensures that e1.equals(e2) implies that e1.hashCode()==e2.hashCode() for any two Entries e1 and e2, as required by the general contract of Object.hashCode.

return	the hash code value for this map entry
See also	hashCode(), equals(Object), equals(Object)

Properties

public Object

getKey()
Returns the key corresponding to this entry.

return	the key corresponding to this entry
Throws	IllegalStateException: implementations may, but are not required to, throw this exception if the entry has been removed from the backing map.

public Object

setValue(Object value)
Replaces the value corresponding to this entry with the specified value (optional operation). (Writes through to the map.) The behavior of this call is undefined if the mapping has already been removed from the map (by the iterator's remove operation).

value	new value to be stored in this entry
return	old value corresponding to the entry
Throws	UnsupportedOperationException: if the `put` operation is not supported by the backing map
Throws	ClassCastException: if the class of the specified value prevents it from being stored in the backing map
Throws	NullPointerException: if the backing map does not permit null values, and the specified value is null
Throws	IllegalArgumentException: if some property of this value prevents it from being stored in the backing map
Throws	IllegalStateException: implementations may, but are not required to, throw this exception if the entry has been removed from the backing map.

public Object

getValue()
Returns the value corresponding to this entry. If the mapping has been removed from the backing map (by the iterator's remove operation), the results of this call are undefined.

return	the value corresponding to this entry
Throws	IllegalStateException: implementations may, but are not required to, throw this exception if the entry has been removed from the backing map.

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Java SE 6