Communicating between 2 GUIs each in a separate class

Question

So I have 2 Java classes, each of which creates a JFrame with various components in it. Each class has its own addComponentsToPane(...) method which is to set up the contents of the frame. this is used in the createAndShowGui() method which is invoked in the main method of the class.

Let's call them class A and B. So the thing is, in A I have a button that when clicked, launches B (simple call of B.main(null). What I'm trying to do is, make it so that when the button is clicked, it will open window B but if clicked again it won't. Now, I can almost manage this just fine by simply setting a boolean value, but the problem is of course if I click once, the window opens and that's fine...but if I close window B and click the appropriate button in A again nothing happens...because the boolean is still saying that B is open.

So what I'm wondering is, given this kind of setup, is there a way that I could reset that boolean in A when B is closed? I was thinking mabe I could do something with a WindowListener in B but if that is a possible solution then I till haven't figured out what to configure it to do..

See [The Use of Multiple JFrames, Good/Bad Practice?](http://stackoverflow.com/a/9554657/418556) One of those frames should probably be a modal dialog. — Andrew Thompson, Aug 08 '13 at 07:16
Am I understanding correctly that A and B are seperate applications (as in, they both have a main class)? Does it need to be this way? — RaptorDotCpp, Aug 08 '13 at 07:16
check the solution at http://stackoverflow.com/questions/8777547/how-can-i-check-that-a-frame-is-open-or-not-in-java — Ashish, Aug 08 '13 at 07:19
Please have a look at this [answer](http://stackoverflow.com/a/9443609/1057230), hope this might help a bit :-) — nIcE cOw, Aug 08 '13 at 11:08

score 2 · Answer 1 · answered Aug 08 '13 at 08:15

Don't destroy B or set the reference to null, just hide it when closed. You can create it hidden on application startup, or just on-demand from A.

A.Button then calls --> B.show().

If B is a JFrame (which it probably should be) you can set the behaviour on close 'X' being clicked by calling JFrame.setDefaultCloseOperation(). The default should already be WindowConstants.HIDE_ON_CLOSE.

LuigiEdlCarno · Answer 2 · 2013-08-08T08:05:09.557

1

Basically what you have to do, is make one Frame your "main" frame, meaning it contains the main method. In your case that would be your Frame A. Then make Frame B (rather use JDialog instead of JFrame) part of Frame A.

Something like:

public MainApp extends JFrame { // Frame A
    ...
    private static CustomWindowB FrameB = null;
    ...
    public static void main(String[] args){
       super();
       FrameB = new CustomWindowB(...);
       ...
    }
    ...
    public void FunctionCalledByButtonClick(){
        if(FrameB == null){
           FrameB = new CustomWindowB(...);
        } else {
           if(FrameB.isVisible()){
              FrameB.hide();
           } else {
              FrameB.show();
           }
        }
    }
 }

And for B you can do:

public CustomWindowB extends JDialog {  // Frame B

   public CustomWindowB(...){
      super();
      ...
      this.setVisible(true);
   }

   public void hide(){
      this.setVisisble(false);
   }

   public void show(){
      this.setVisisble(true);
   }
}

edited Aug 08 '13 at 08:05

answered Aug 08 '13 at 07:24

LuigiEdlCarno

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Don't extend frame or other top level containers. Instead create & use an instance of one. – Andrew Thompson Aug 08 '13 at 08:06
@AndrewThompson What is the drawback of extending a top level container over modifying and instance. I added `super();` for clarity. – LuigiEdlCarno Aug 08 '13 at 08:08
1

When a GUI needs a button or a label, do you extend them? If you do, you'd be almost unique in doing so. If not, ask yourself *why* the top level contain is different. For more on the general principle, see [Composition over inheritance](http://en.wikipedia.org/wiki/Composition_over_inheritance). – Andrew Thompson Aug 08 '13 at 08:16

Communicating between 2 GUIs each in a separate class

2 Answers2