java.util

Class Objects

java.lang.Object

java.util.Objects

public final class Objects
extends Object

Backport of java.util.Objects#hash(Object...) and java.util.Objects#hashCode() from Java 7 into Java 6.

Author:

Markus KARG (mkarg@java.net)

Constructor Summary

Constructors

Constructor and Description
Objects()

Method Summary

Methods

Modifier and Type	Method and Description
static boolean	equals(Object a, Object b) Returns true if the arguments are equal to each other and false otherwise.
static int	hash(Object... values) Generates a hash code for a sequence of input values.
static int	hashCode(Object o) Returns the hash code of a non-null argument and 0 for a null argument.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Objects

public Objects()

Method Detail

hash

public static final int hash(Object... values)

Generates a hash code for a sequence of input values. The hash code is generated as if all the input values were placed into an array, and that array were hashed by calling Arrays.hashCode(Object[]).

This method is useful for implementing Object.hashCode() on objects containing multiple fields. For example, if an object that has three fields, x, y, and z, one could write:

 @Override
 public int hashCode() {
        return Objects.hash(x, y, z);
 }
 

Parameters:

values - the values to be hashed

Returns:

a hash value of the sequence of input values

See Also:

Arrays.hashCode(Object[]), List.hashCode()

hashCode

public static final int hashCode(Object o)

Returns the hash code of a non-null argument and 0 for a null argument.

Parameters:

o - an object

Returns:

the hash code of a non-null argument and 0 for a null argument

See Also:

Object.hashCode()

equals

public static final boolean equals(Object a,
             Object b)

Returns true if the arguments are equal to each other and false otherwise. Consequently, if both arguments are null, true is returned and if exactly one argument is null, false is returned. Otherwise, equality is determined by using the equals method of the first argument.

Parameters:

a - an object

b - an object to be compared with a for equality

Returns:

true if the arguments are equal to each other and false otherwise

See Also:

Object.equals(Object)