java.util

Class AbstractMap.SimpleEntry<K,V>

java.lang.Object

java.util.AbstractMap.SimpleEntry<K,V>

All Implemented Interfaces:

Map.Entry<K,V>

Enclosing class:

AbstractMap<K,V>

public static class AbstractMap.SimpleEntry<K,V>
extends Object
implements Map.Entry<K,V>

A class which implements Map.Entry. It is shared by HashMap, TreeMap, Hashtable, and Collections. It is not specified by the JDK, but makes life much easier.

Since:

1.6

Author:

Jon Zeppieri, Eric Blake (ebb9@email.byu.edu)

Constructor Summary

Constructors

Constructor and Description
SimpleEntry(K newKey, V newValue) Basic constructor initializes the fields.
SimpleEntry(Map.Entry<? extends K,? extends V> entry)

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 newVal) Replaces the value with the specified object.
String	toString() This provides a string representation of the entry.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

SimpleEntry

public SimpleEntry(K newKey,
                   V newValue)

Basic constructor initializes the fields.

Parameters:

newKey - the key

newValue - the value

SimpleEntry

public SimpleEntry(Map.Entry<? extends K,? extends V> entry)

Method Detail

equals

public 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 ? ((HashMap) o).getKey() == null
           : getKey().equals(((HashMap) o).getKey()))
       && (getValue() == null ? ((HashMap) o).getValue() == null
           : getValue().equals(((HashMap) o).getValue()))

Specified by:

equals in interface Map.Entry<K,V>

Overrides:

equals in class Object

Parameters:

o - the object to compare

Returns:

true if it is equal

getKey

public K getKey()

Get the key corresponding to this entry.

Specified by:

getKey in interface Map.Entry<K,V>

Returns:

the key

getValue

public V getValue()

Get the value corresponding to this entry. If you already called Iterator.remove(), the behavior undefined, but in this case it works.

Specified by:

getValue in interface Map.Entry<K,V>

Returns:

the value

hashCode

public 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())

Specified by:

hashCode in interface Map.Entry<K,V>

Overrides:

hashCode in class Object

Returns:

the hash code

setValue

public V setValue(V newVal)

Replaces the value with the specified object. This writes through to the map, unless you have already called Iterator.remove(). It may be overridden to restrict a null value.

Specified by:

setValue in interface Map.Entry<K,V>

Parameters:

newVal - the new value to store

Returns:

the old value

Throws:

NullPointerException - if the map forbids null values.

UnsupportedOperationException - if the map doesn't support put().

ClassCastException - if the value is of a type unsupported by the map.

IllegalArgumentException - if something else about this value prevents it being stored in the map.

toString

public String toString()

This provides a string representation of the entry. It is of the form "key=value", where string concatenation is used on key and value.

Overrides:

toString in class Object

Returns:

the string representation