java.util

Interface Map.Entry<K,V>

All Known Implementing Classes:

AbstractMap.SimpleEntry, AbstractMap.SimpleImmutableEntry

Enclosing interface:

Map<K,V>

public static interface Map.Entry<K,V>

A map entry (key-value pair). The Map.entrySet() method returns a set view of these objects; there is no other valid way to come across them. These objects are only valid for the duration of an iteration; in other words, if you mess with one after modifying the map, you are asking for undefined behavior.

Since:

1.2

Author:

Original author unknown, Eric Blake (ebb9@email.byu.edu)

See Also:

Map, Map.entrySet()

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o) Compares the specified object with this entry.
K	getKey() Get the key corresponding to this entry.
V	getValue() Get the value corresponding to this entry.
int	hashCode() Returns the hash code of the entry.
V	setValue(V value) Replaces the value with the specified object (optional operation).

Method Detail

equals

boolean equals(Object o)

Compares the specified object with this entry. Returns true only if the object is a mapping of identical key and value. In other words, this must be:

(o instanceof Map.Entry)
&& (getKey() == null ? ((Map.Entry) o).getKey() == null
                     : getKey().equals(((Map.Entry) o).getKey()))
&& (getValue() == null ? ((Map.Entry) o).getValue() == null
                       : getValue().equals(((Map.Entry) o).getValue()))

Overrides:

equals in class Object

Parameters:

o - the object to compare

Returns:

true if it is equal

getKey

K getKey()

Get the key corresponding to this entry.

Returns:

the key

getValue

V getValue()

Get the value corresponding to this entry. If you already called Iterator.remove(), this is undefined.

Returns:

the value

hashCode

int hashCode()

Returns the hash code of the entry. This is defined as the exclusive-or of the hashcodes of the key and value (using 0 for null). In other words, this must be:

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

Overrides:

hashCode in class Object

Returns:

the hash code

setValue

V setValue(V value)

Replaces the value with the specified object (optional operation). This writes through to the map, and is undefined if you already called Iterator.remove().

Parameters:

value - the new value to store

Returns:

the old value

Throws:

UnsupportedOperationException - if the operation is not supported

ClassCastException - if the value is of the wrong type

IllegalArgumentException - if something about the value prevents it from existing in this map

NullPointerException - if the map forbids null values