org.apache.commons.lang
Class ObjectUtils.Null
java.lang.Object
|
+--org.apache.commons.lang.ObjectUtils.Null
- All Implemented Interfaces:
- java.io.Serializable
- Enclosing class:
- ObjectUtils
- public static class ObjectUtils.Null
- extends java.lang.Object
- implements java.io.Serializable
Class 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.
- See Also:
- Serialized Form
Constructor Summary |
private |
ObjectUtils.Null()
Restricted constructor - singleton |
Method Summary |
private java.lang.Object |
readResolve()
Ensure singleton. |
Methods inherited from class java.lang.Object |
, clone, equals, finalize, getClass, hashCode, notify, notifyAll, registerNatives, toString, wait, wait, wait |
ObjectUtils.Null
private ObjectUtils.Null()
- Restricted constructor - singleton
readResolve
private java.lang.Object readResolve()
- Ensure singleton.
- Returns:
- the singleton value
Copyright (c) 2001-2002 - Apache Software Foundation