ObjectUtils.Null

java.lang.Object
- org.apache.commons.lang3.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 HashMap.get(java.lang.Object) 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

- Field Summary
  
  Fields
  Modifier and Type Field Description
  
  private static long serialVersionUID
  Required for serialization support.
- Constructor Summary
  
  Constructors
  Constructor Description
  
  Null()
  Restricted constructor - singleton.
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  private java.lang.Object readResolve()
  Ensure singleton.
  - Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - serialVersionUID
```
private static final long serialVersionUID
```
    Required for serialization support. Declare serialization compatibility with Commons Lang 1.0
    
    See Also:
    
    Serializable, Constant Field Values
- Constructor Detail
  - Null
```
Null()
```
    Restricted constructor - singleton.
- Method Detail
  - readResolve
```
private java.lang.Object readResolve()
```
    Ensure singleton.
    
    Returns:
    
    the singleton value