Question

I started writing a small program to learn a bit more about java and try to design my layouts by hand without always using NetBeans.

Thing is, when I run my project and close it, it won’t stop running in NetBeans, so everytime I re-run it creates another run. By searching and looking at another GUI I had created using NetBeans I thought adding the

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

would do the trick, but I guess I am wrong.

Can someone please explain me what I should do?

Here is a SSCCE of my programa: http://pastebin.com/QhKpwdDw

Thank you very much in advance!

Answer 1

You might want to take a look at this question: How to close a Java Swing application from the code, as it deals with closing the application in general and also how to ensure it completely terminated.

But to answer your question quickly, there are a couple of options.

Option 1

Since you are extending JFrame in your class, you can just use EXIT_ON_CLOSE to quit.

setDefaultCloseOperation(EXIT_ON_CLOSE);

NOTE: EXIT_ON_CLOSE exits all JFrames in your application, not just the one it is applied to.

Option 2

This is most likely not the answer you want, but DISPOSE_ON_CLOSE will close only the JFrame you are applying it to.

If you have multiple JFrames open, or if you have any other Threads, they will keep running and the program will not end. But if you only have one Thread and one JFrame, this will close the application.

setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);

My Preference

I would go with Option 1, disagreeing with everyone else. It is directly tied to JFrame and not dependent on WindowConstants, which makes things cleaner and more reliable. But more importantly, it closes all of the windows, not just the one that you apply it to.

Even though it looks like you only have one window, you may have other internal Threads elsewhere in your program that NetBeans is throwing in there.

To be sure everything closes, you want to use EXIT_ON_CLOSE.

Extra Information

For a discussion on how DISPOSE_ON_CLOSE and EXIT_ON_CLOSE differ: http://www.coderanch.com/t/340183/GUI/java/DISPOSE-CLOSE-vs-EXIT-CLOSE

Documentation on JFrame's EXIT_ON_CLOSE: http://docs.oracle.com/javase/1.4.2/docs/api/javax/swing/JFrame.html#EXIT_ON_CLOSE

Documentation on DISPOSE_ON_CLOSE and other WindowConstants: http://docs.oracle.com/javase/1.5.0/docs/api/javax/swing/WindowConstants.html#DISPOSE_ON_CLOSE