public static class ObjectUtils.Null extends Object implements 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.
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