JButton Adding Problem

Question

Hi everyone,
First, like to say I appreciate all your help. I have come here for help before and I always get my questions answered. Thanks.
Here is my problem:
I've created a JPanel and added this panel to a JFrame. The JPanel has a MouseListener and a MouseMotionListener. I am tryin to add JButtons to the JPanel at positions passed from the MouseMotionListener, but everytime I attempt this, the JButton pops to the top left corner of the screen. I don't know if I should use a layout manager on the JPanel and if I do, I don't know which one to use. I've tried using the SpringLayout, but was unsuccessful at deploying it.
Appreciate any help.
Thanks again.

Answer 1

Null layout is not recommended, see my earlier post. Here is a simple SpringLayout that does the same thing.
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
public class TestSpring extends JFrame
     Container cp;
     int mpx, mpy;
     int MINX= 80;
     int MINY=20;
     JLabel txt = new JLabel("use mouse to position buttons, drag to set size");
     SpringLayout slay = new SpringLayout();
     MouseInputAdapter mia = new MouseInputAdapter()
          public void mousePressed(MouseEvent evt){mousePress(evt);}
          public void mouseReleased(MouseEvent evt){mouseRelease(evt);}
     TestSpring()
          super("TestSpring");
          cp = getContentPane();
          addWindowListener(new WindowAdapter()
          {public void windowClosing(WindowEvent evt){System.exit(0);}});
          cp.addMouseListener(mia);
          cp.setLayout(slay);
          cp.add(txt);
          setBounds(0,0,700,400);
     void mousePress(MouseEvent evt)
          mpx = evt.getX();
          mpy = evt.getY();
     void mouseRelease(MouseEvent evt)
          int x,y,dx,dy;
          x = evt.getX();
          y=evt.getY();
          dx = x-mpx;
          dy = y-mpy;
          if(dx < 0){dx = -dx; mpx = x;}
          if(dy < 0){dy = -dy; mpy = y;}
          JButton jb = new JButton(mpx+","+mpy);
          cp.add(jb);
          setCPosition(jb,mpx,mpy);
          if(dx < MINX)dx = MINX;
          if(dy < MINY)dy = MINY;
          setCSize(jb, dx, dy);
          cp.validate();
     void setCPosition(Component c, int x, int y)
          slay.getConstraints(c).setX(Spring.constant(x));
          slay.getConstraints(c).setY(Spring.constant(y));
     void setCSize(Component c, int w, int h)
          slay.getConstraints(c).setWidth(Spring.constant(w));
          slay.getConstraints(c).setHeight(Spring.constant(h));
     // the main startup function
     public static void main(String[] args)
          new TestSpring().show();
}