Package com.intellij.util

Class NotNullizer

java.lang.Object

com.intellij.util.NotNullizer

public final class NotNullizer
extends java.lang.Object

Has its own null-object instance, which is hidden from outside world, preventing accidental "unwrapping".

Constructor Summary

Constructors

Constructor and Description
NotNullizer(java.lang.String name)

Method Summary

Modifier and Type	Method and Description
<T> T	notNullize(T value) "Wraps" null with null-object.
<T> T	nullize(T value) "Unwraps" null from the value returned by notNullize(Object).

Methods inherited from class java.lang.Object

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

Constructor Detail

NotNullizer

public NotNullizer(java.lang.String name)

Method Detail

notNullize

public <T> T notNullize(T value)

"Wraps" null with null-object.

Useful when some generic data structure A does not allow nulls, but there is a need to implement another structure B on top of A which should support nulls.
Returned value should never be presented to clients of structure B, and it must be "unwrapped" back with nullize(Object).
Casting the value to anything but Object will result in ClassCastException, this means the value cannot be used anywhere where T is a specific type different from Object.

Returns:

null wrapper if value is null, otherwise original value

See Also:

nullize(Object)

nullize

public <T> T nullize(T value)

"Unwraps" null from the value returned by notNullize(Object).

Returns:

null if value is the null wrapper, otherwise original value

See Also:

notNullize(Object)