swing - Java - how do I prevent WindowClosing from actually closing the window

Question

I seem to have the reverse problem to most people. I have the following pretty standard code to see if the user wants to do some saves before closing the window:

  frame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
  frame.addWindowListener(new WindowAdapter() {
     public void windowClosing(WindowEvent ev) {
      boolean close = true;
         // check some files, asking if the user wants to save
         // YES and NO handle OK, but if the user hits Cancel on any file,
         //   I want to abort the close process     
         // So if any of them hit Cancel, I set "close" to false
      if (close) {
          frame.dispose();
          System.exit(0);
         }
       }            
});

No matter what I try, the window always closes when I come out of windowClosing. Changing WindowAdapter to WindowListener doesn't make any difference. What is weird is that the documentation explicitly says "If the program does not explicitly hide or dispose the window while processing this event, the window close operation will be cancelled," but it doesn't work that way for me. Is there some other way of handling the x on the frame? TIA

Answer 1

I've just tried this minimal test case:

import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JFrame;
import javax.swing.WindowConstants;

public class Test {

    public static void main(String[] args) {
        final JFrame frame = new JFrame("Test");
        frame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent ev) {
                //frame.dispose();
            }
        });
        frame.setVisible(true);
    }

}

If I keep the dispose call commented, and hit the close button, the window doesn't exit. Uncomment that and hit the close button, window closes.

I'd have to guess that something is wrong in your logic to set your "close" variable. Try double checking that.