java.util

Class AbstractMap.SimpleImmutableEntry<K,V>

java.lang.Object

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

All Implemented Interfaces:

Serializable, Map.Entry<K,V>

Enclosing class:

AbstractMap<K,V>

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

An Entry maintaining an immutable key and value. This class does not support method setValue. This class may be convenient in methods that return thread-safe snapshots of key-value mappings.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
SimpleImmutableEntry(K key, V value)
SimpleImmutableEntry(Map.Entry<? extends K,? extends V> entry)

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o) Indicates whether some other object is "equal to" this one.
K	getKey() Returns the key corresponding to this entry.
V	getValue() Returns the value corresponding to this entry.
int	hashCode() Returns a hash code value for the object.
V	setValue(V value) Replaces the value corresponding to this entry with the specified value (optional operation).
String	toString() Returns a string representation of the object.

Methods inherited from class java.lang.Object

clone, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

SimpleImmutableEntry

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

SimpleImmutableEntry

public SimpleImmutableEntry(K key,
                            V value)

Method Detail

equals

public boolean equals(@Nullable
                      Object o)

Description copied from class: Object

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

Specified by:

equals in interface Map.Entry<K,V>

Overrides:

equals in class Object

Parameters:

o - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

See Also:

Object.hashCode(), HashMap

getKey

public K getKey()

Description copied from interface: Map.Entry

Returns the key corresponding to this entry.

Specified by:

getKey in interface Map.Entry<K,V>

Returns:

the key corresponding to this entry

getValue

public V getValue()

Description copied from interface: Map.Entry

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.

Specified by:

getValue in interface Map.Entry<K,V>

Returns:

the value corresponding to this entry

hashCode

public int hashCode()

Description copied from class: Object

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java^TM programming language.)

Specified by:

hashCode in interface Map.Entry<K,V>

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

setValue

public V setValue(V value)

Replaces the value corresponding to this entry with the specified value (optional operation). This implementation simply throws UnsupportedOperationException, as this class implements an immutable map entry.

Specified by:

setValue in interface Map.Entry<K,V>

Parameters:

value - new value to be stored in this entry

Returns:

(Does not return)

Throws:

UnsupportedOperationException - always

toString

public String toString()

Description copied from class: Object

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())
 

Overrides:

toString in class Object

Returns:

a string representation of the object.