Thread: A GUI issue.

Hello there,

I'd like to quickly start off by saying after contemplating what section to post this in this one seemed more appropriate then any of the other sections, though I have a gut feeling I'm still wrong.

I'm fairly week at OO programming, no particular reason aside from I'm much more used to C which is more procedural.

My problem at the moment is (and forgive my terms they're probably going to be wrong) I have two graphic classes 'startMenu' and 'Camera', which are part of a game I'm getting to grips with. I want to make it so that 'startMenu' will "go away" after the user hits enter, which I've currently implemented very poorly with a scan statement. From running this code with the other classes I find that nothing comes up (no window) until I hit enter. In this case it seems to skip (although is probably appearing for a nano second) everything in 'startMenu' and just goes to 'Camera'.

Because I'm so used to procedural I'm just so baffled by the fact it's not similar to C in the sense that a scanf statement will "Stop" everything and wait for input; where as here it waits for input then starts.

How do I make it so that 'startMenu' will show in the window and after the key enter is pressed it will show 'Camera'? (If that question makes any sense).

I also have some additional questions:

• How do I "take away" a class from the JFrame? I'm '.add' ing stuff to it is there a similar command to remove it from the frame entirely instead of just being in the background.
• How do I layer graphics in the JFrame? I've heard and looked at panels, content and just '.add' ing it to the window in the right order. What would be the best option for a game?
• How can I make an Image a button? I've looked around but all tutorials regarding this are just "Put image on button", I want the image to act as a button.

Thank you for your time, I hope I haven't wasted it.

class Thing 
{
 
  public Thing()
  {
    JFrame mainwindow = new JFrame("Dooby");
    mainwindow.add(new startMenu());
 
    Scanner scan = new Scanner(System.in);
    String startit = scan.nextLine();
 
    mainwindow.add(new Camera());
    mainwindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    mainwindow.setSize(800, 600);
    mainwindow.setVisible(true);
    mainwindow.setLocationRelativeTo(null);
  }
 
  public static void main (String[] args)
  {
    new Thing();
  }
}

Thanks! I went with your mouselistener idea and I've run into another little problem.

I'd like what's displayed to change from 'startMenu' to 'Camera' upon a click (there are some pointless lines of code in there). But it doesn't actually change what's displayed. What's going on?

I can have the code, without Mouselistener, to have:

    mainwindow.add(new startMenu());
    mainwindow.add(new Camera());

And it will display what's in Camera.

But here's the actual code itself, what am I doing wrong here with the mouse listener?

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.util.Scanner;
 
class Thing extends JFrame
{
  int x, y;
  private JFrame mainwindow = new JFrame("Dooby");
 
  public Thing()
  {
    mainwindow.add(new startMenu());
    Handlerclass handler = new Handlerclass();
    mainwindow.addMouseListener(handler);
    mainwindow.addMouseMotionListener(handler);
    mainwindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    mainwindow.setSize(800, 600);
    mainwindow.setVisible(true);
    Scanner scan = new Scanner(System.in);
    String startit = scan.nextLine();
    mainwindow.setLocationRelativeTo(null);
  }
 
  public static void main (String[] args)
  {
    new Thing();
  }
 
  private class Handlerclass implements MouseListener, MouseMotionListener
  {
    public void mouseClicked(MouseEvent e)
    {
      mainwindow.add(new Camera());
      System.err.println("Boo");
    }
    public void mousePressed(MouseEvent e)
    {
    }
    public void mouseReleased(MouseEvent e)
    {
    }
    public void mouseEntered(MouseEvent e)
    {
    }
    public void mouseExited(MouseEvent e)
    {
    }
    public void mouseMoved(MouseEvent e)
    {
    }
    public void mouseDragged(MouseEvent e)
    {
    }
  }
}

what am I doing wrong here with the mouse listener?

Can you explain what the problem is?

Originally Posted by Norm

Can you explain what the problem is?

Ah, sorry!

When I click, the content of 'Camera' is not displayed; instead the content of 'startMenu' remains on the screen.

Does the println statement execute and print "Boo" on the console?

Where do you remove the old contents of the container?


After you add something to a container, you need to tell the container and its layout manager to redo the layout of all the components in the container. The Container class has methods you can use to tell it to do that.

Originally Posted by Norm

Does the println statement execute and print "Boo" on the console?

After you add something to a container, you need to tell the container and its layout manager to redo the layout of all the components in the container. The Container class has methods you can use to tell it to do that.

It does print "Boo" every time I click.

So simply "refresh" the layout? May I ask why when I have mainwindow.add(startMenu()) with mainwindow.add(Camera()) directly after it that the window actually displays the content of 'Camera' (While briefly flashing the content of startMenu)?

Would this be a good resource JAVA Platform SE6 to look for a refresh method?

Thank you by the way!

Originally Posted by KevinWorkman

Yeah, the API is your best friend. The method you're looking for is validate or revalidate. Alternatively, you could look into CardLayout.

Ok, using validate now.

It works and changes the content of the window to the 'Camera' class.

Now 'Camera' uses a working keylistener, but in switching to it with validate I loose control... Pressing the keys doesn't yeild any output from the program. What's going wrong?