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.
Modifier and Type | Field and Description |
---|---|
private static long |
serialVersionUID
Required for serialization support.
|
Constructor and Description |
---|
Null()
Restricted constructor - singleton.
|
Modifier and Type | Method and Description |
---|---|
private java.lang.Object |
readResolve()
Ensure singleton.
|
private static final long serialVersionUID
Serializable
,
Constant Field Values