Swing dispose() doesn't actually null the current object reference?

Question

After wondering whether disposing my frame would return a null (if checked) I went ahead and tested it out. I've searched on dispose() but most of the articles I read just state when to use it, not what it actually does. I tried out the sample code, maybe my code is simply incorrect but if it's not. What does dispose() actually do inside the JVM?

If someone does find a link related to this, please post it so I can remove this question

http://docs.oracle.com/javase/6/docs/api/java/awt/Window.html#dispose%28%29 — martinez314, Aug 15 '14 at 21:35
[Here](http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/awt/Window.java#Window.doDispose%28%29) you can see the implementation. — Jens, Aug 15 '14 at 21:37
If you agree with what I said, then re-read your question and your code: it makes no sense. How could the frame object set all the references on itself to null? It doesn't know them. — JB Nizet, Aug 15 '14 at 21:38
See also this related [Q&A](http://stackoverflow.com/q/6309407/230513) and partial [list](http://stackoverflow.com/a/2486200/230513). — trashgod, Aug 16 '14 at 00:07

score 1 · Answer 1 · answered Aug 15 '14 at 21:37

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1) No method ever can set your variable to null. Never ever. It may change an internal state so any future call may throw an error (e.g. with a Socket), but the variable itself won't be changed. You need to do this explicitly yourself.

2) Read the javadocs :)

Releases all of the native screen resources used by this Window, its subcomponents, and all of its owned children. That is, the resources for these Components will be destroyed, any memory they consume will be returned to the OS, and they will be marked as undisplayable. [...]

answered Aug 15 '14 at 21:37

ZeissS

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Yea seems like a COMPLETELY newbie question from my part! I do need to learn the basics – Juxhin Aug 15 '14 at 21:40
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No problem - other people can still stumble over the same thing. That why we are here. – ZeissS Aug 16 '14 at 11:08

score 1 · Accepted Answer · answered Aug 15 '14 at 21:38

Objects can change their state. However, they cannot willy-nilly change any state in the entire collection of other objects.

So, if you call any method on an object, it will not have a direct impact on any reference to that object from any possible other object.

In your case, dispose() is releasing the in-object references to the wrapped OS level components, not removing the Java object from the environment (and clearing out its references).

@Juxhin, Anytime. Glad to help. – Edwin Buck Aug 15 '14 at 21:53 — Edwin Buck, Aug 15 '14 at 21:53

Swing dispose() doesn't actually null the current object reference?

2 Answers2