1106: Mainline

All the key gridbag-layout machinery is exhibited in the following example, in which the repetitive part of component placement is done in the placeComponent method, keeping clutter controlled:

import java.awt.*; 
import javax.swing.*; 
public class TestPanel extends JPanel { 
 public TestPanel () { 
  GridBagLayout gbl = new GridBagLayout(); 
  setLayout(gbl); 
  GridBagConstraints gbc = new GridBagConstraints(); 
  // Fill both ways and allow expansion of all components: 
  gbc.fill = GridBagConstraints.BOTH; 
  gbc.weightx = 1.0;     
  gbc.weighty = 1.0; 
  // Place components: 
  placeComponent(0, 0, 1, 2, "A", gbl, gbc); 
  placeComponent(1, 0, 1, 1, "B", gbl, gbc); 
  placeComponent(0, 2, 1, 3, "C", gbl, gbc); 
  placeComponent(1, 1, 1, 4, "D", gbl, gbc); 
  placeComponent(2, 0, 1, 1, "E", gbl, gbc); 
  placeComponent(2, 1, 1, 1, "F", gbl, gbc); 
  placeComponent(2, 2, 1, 1, "G", gbl, gbc); 
  placeComponent(2, 3, 1, 1, "H", gbl, gbc); 
  placeComponent(2, 4, 1, 1, "I", gbl, gbc); 
 } 
 // Handle placement details: 
 public void placeComponent  
  (int x, int y, int w, int h,  
   String s, GridBagLayout l, GridBagConstraints c) { 
  c.gridx = x;          c.gridwidth = w; 
  c.gridy = y;          c.gridheight = h; 
  TestButton p = new TestButton(s); 
  l.setConstraints(p, c);   add(p); 
 } 
}