com.googlecode.jbp.common.util
Class Objects

java.lang.Object
  com.googlecode.jbp.common.util.Objects

public final class Objects
extends Object

Backports some methods of the java.util.Objects class provided in the JDK 7.

Author:

Yannick LOTH - yannick AT littlej.biz -

Method Summary

static <T> int	compare(T firstParam, T secondParam, Comparator<? super T> comparatorParam) Returns 0 if the arguments are identical and c.compare(a, b) otherwise.
static boolean	deepEquals(Object firstParam, Object secondParam) Returns true if the arguments are deeply equal to each other and false otherwise.
static boolean	equals(Object firstParam, Object secondParam) Returns true if the arguments are equal to each other and false otherwise.
static int	hash(Object... objectsParam) Generates a hash code for a sequence of input values.
static int	hashCode(Object objectParam) Returns the hash code of a non-null argument and 0 for a null argument.
static String	toString(Object objectParam) Returns the result of calling toString for a non-null argument and "null" for a null argument.
static String	toString(Object objectParam, String nullDefaultParam) Returns the result of calling toString on the first argument if the first argument is not null and returns the second argument otherwise.

Methods inherited from class java.lang.Object

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

Method Detail

compare

public static <T> int compare(T firstParam,
                              T secondParam,
                              Comparator<? super T> comparatorParam)

Returns 0 if the arguments are identical and c.compare(a, b) otherwise. Consequently, if both arguments are null 0 is returned.

Note that if one of the arguments is null, a NullPointerException may or may not be thrown depending on what ordering policy, if any, the Comparator chooses to have for null values.

Type Parameters:

T - the type of the objects being compared

Parameters:

firstParam - an object

secondParam - an object to be compared with a

comparatorParam - the Comparator to compare the first two arguments

Returns:

0 if the arguments are identical and c.compare(a, b) otherwise.

See Also:

Comparable, Comparator

deepEquals

public static boolean deepEquals(Object firstParam,
                                 Object secondParam)

Returns true if the arguments are deeply equal to each other and false otherwise. Two null values are deeply equal. If both arguments are arrays, the algorithm in Arrays.deepEquals is used to determine equality. Otherwise, equality is determined by using the equals method of the first argument.

Parameters:

firstParam - an object

secondParam - an object to be compared with a for deep equality

Returns:

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

See Also:

Arrays.deepEquals(Object[], Object[]), equals(Object, Object)

equals

public static boolean equals(Object firstParam,
                             Object secondParam)

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:

firstParam - an object

secondParam - 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)

hash

public static int hash(Object... objectsParam)

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);
 }
 

Warning: When a single object reference is supplied, the returned value does not equal the hash code of that object reference. This value can be computed by calling hashCode(Object).

Parameters:

objectsParam - 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 int hashCode(Object objectParam)

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

Parameters:

objectParam - an object

Returns:

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

See Also:

Object.hashCode()

toString

public static String toString(Object objectParam)

Returns the result of calling toString for a non-null argument and "null" for a null argument.

Parameters:

objectParam - an object

Returns:

the result of calling toString for a non-null argument and "null" for a null argument

See Also:

Object.toString(), String.valueOf(Object)

toString

public static String toString(Object objectParam,
                              String nullDefaultParam)

Returns the result of calling toString on the first argument if the first argument is not null and returns the second argument otherwise.

Parameters:

objectParam - an object

nullDefaultParam - string to return if the first argument is null

Returns:

the result of calling toString on the first argument if it is not null and the second argument otherwise.

See Also:

toString(Object)