Getting data out of a thread... how?

Alright, so I racked my brain over this problem and thought maybe I could work with it kind of like FileDialog seems to work in that you create a new FileDialog(variables needed) and then after it runs (after you setVisible(true)) you can call something to get the information that was stored inside like this: fd.getDirectory()...

So I tried something like that here:

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1.     public static void main(String args[]) {
2.         ArrayList<String> temp = new ArrayList<String>(2);
3.         temp.add("First Tag\\");
4.         temp.add("Second Tag\\");
5.         final TagChoosingWindow TCW = new TagChoosingWindow(temp);
6.         //Schedule a job for the event-dispatching thread:
7.         //creating and showing this application's GUI.
8.         javax.swing.SwingUtilities.invokeLater(new Runnable() {
9.             public void run() {
10.                 TCW.createAndShowGUI(); 
11.             }
12.         });
13.         Utilities.print(TCW.getAL()); //Should print the arraylist to the screen one component at a time
14.     }
15.  

but this spits out a NullPointerException error because main obviously doesn't wait for the thread to finish before trying to access TCW.getAL()...

So how do I get around this? This GUI is supposed to finish when you press the done button and I hope I can then just call a method .getAL() and get my ArrayList when it's done.

What do you guys suggest? I've had zero experience with threading before so this simple concept of getting information out of a thread is eluding me. I want to avoid having the thread do some large operation when it's finished.


Thanks for all your help
-blazed

Your (main) thread can 'join' the other thread: when it stops, your thread continues
and you can grab the ArrayList from the other object.

kind regards,

Jos

Shouldn't you use a modal JDialog instead? It takes care of suspending
other threads.

kind regards,

Jos