Map.Entry (Java Platform SE 6)

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java.util
interface Map.Entry

All Known Implementing Classes:: AbstractMap.SimpleEntry, AbstractMap.SimpleImmutableEntry

public static interface Map.Entry

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.

Method Summary
`boolean`	`equals(Object o)` Compares the specified object with this entry for equality.
`Object`	`getKey()` Returns the key corresponding to this entry.
`Object`	`getValue()` Returns the value corresponding to this entry.
`int`	`hashCode()` Returns the hash code value for this map entry.
`Object`	`setValue(Object value)` Replaces the value corresponding to this entry with the specified value (optional operation).

Method Detail

equals

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.

Overrides:: equals in class Object
Parameters:: o - object to be compared for equality with this map entry
Returns:: true if the specified object is equal to this map entry

getKey

public Object getKey()

Returns the key corresponding to this entry.

Returns:: the key corresponding to this entry

getValue

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.

Returns:: the value corresponding to this entry

hashCode

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.

Overrides:: hashCode in class Object
Returns:: the hash code value for this map entry

setValue

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).

Parameters:: value - new value to be stored in this entry
Returns:: old value corresponding to the entry