Re: Alignment Problem

chester_fried@hotmail.com wrote:

Look at the program below to see how to get GridBagLayout to put all of
your components at the top of the container. The trick is to set the
weighty to 0.0 for all rows except the last one. That one gets a
weighty of 1.0 causing it to take all of the extra vertical space.

GridBagConstraints is the most powerful layout manager but also the most
difficult to master.

As to your other problem, just remove the old components, add the new
components and call validate() on the container. That should be all
that is required.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class test extends JPanel {
     public test() {
         setPreferredSize(new Dimension(400,300));

         setBackground(Color.BLUE);

         setLayout(new GridBagLayout());

         GridBagConstraints c = new GridBagConstraints();
         c.fill = GridBagConstraints.HORIZONTAL;
         c.anchor = GridBagConstraints.NORTH;
         c.weighty = 0.0;
         c.gridy = 0;

         JButton[] buttons = new JButton[6];
         String[] strs = { "one","two","three","four","five","six" };
         for (int i=0; i<buttons.length; i++) {
             buttons[i] = new JButton(strs[i]);
             add(buttons[i],c);
             if (i == 1)
                 ++c.gridy;
             if (i == 3) {
                 ++c.gridy;
                 c.weighty = 1.0;
             }
         }
     }

     public static void main(String[] args) {
         Runnable r = new Runnable() {
             public void run() {
                 JFrame f = new JFrame();
                 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                 test t = new test();
                 f.add(t,BorderLayout.CENTER);
                 f.pack();
                 f.setVisible(true);
             }
         };
         EventQueue.invokeLater(r);
     }
}

--

Knute Johnson
email s/nospam/knute/