org.apache.commons.lang
Class ObjectUtils

java.lang.Object
  |
  +--org.apache.commons.lang.ObjectUtils

public class ObjectUtils

extends java.lang.Object

Common Object manipulation routines.

Version:

$Id: ObjectUtils.java,v 1.4 2002/09/22 09:18:33 scolebourne Exp $

Author:

Nissim Karpenstein, Janek Bogucki, Daniel Rall, Stephen Colebourne

Inner Class Summary

static class

ObjectUtils.Null Class used as a null placeholder where null has another meaning.

Field Summary

static ObjectUtils.Null

NULL Singleton used as a null placeholder where null has another meaning.

Constructor Summary

ObjectUtils()
ObjectUtils instances should NOT be constructed in standard programming.

Method Summary

static java.lang.Object	defaultIfNull(java.lang.Object object, java.lang.Object defaultValue) Returns a default value if the object passed is null.
static boolean	equals(java.lang.Object object1, java.lang.Object object2) Compares two objects for equality, where either one or both objects may be null.
static java.lang.String	identityToString(java.lang.Object object) Gets the toString that would be produced by Object if a class did not override toString itself.

Methods inherited from class java.lang.Object

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

Field Detail

NULL

public static final ObjectUtils.Null NULL

Singleton used as a null placeholder where null has another meaning.

For example, in a HashMap the get(key) method returns null if the Map contains null or if there is no matching key. The Null placeholder can be used to distinguish between these two cases.

Another example is HashTable, where null cannot be stored.

This instance is Serializable.

Constructor Detail

ObjectUtils

public ObjectUtils()

ObjectUtils instances should NOT be constructed in standard programming. Instead, the class should be used as ObjectUtils.defaultIfNull("a","b");. This constructor is public to permit tools that require a JavaBean instance to operate.

Method Detail

defaultIfNull

public static java.lang.Object defaultIfNull(java.lang.Object object,
                                             java.lang.Object defaultValue)

Returns a default value if the object passed is null.

Parameters:

object - the object to test

defaultValue - the default value to return

Returns:

object if it is not null, defaultValue otherwise

equals

public static boolean equals(java.lang.Object object1,
                             java.lang.Object object2)

Compares two objects for equality, where either one or both objects may be null.

Parameters:

object1 - the first object

object2 - the second object

Returns:

true if the values of both objects are the same

identityToString

public static java.lang.String identityToString(java.lang.Object object)

Gets the toString that would be produced by Object if a class did not override toString itself. Null will return null.

Parameters:

object - the object to create a toString for, may be null

Returns:

the default toString text, or null if null passed in