Event Handling with the Swing Component Set - The Definitive Guide to Java Swing - page 53

Listing 2-13. Reversing Focus Traversal
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.Comparator;
import java.util.Arrays;
import java.util.List;
public class NextComponentSample {
public static void main(String args[]) {
Runnable runner = new Runnable() {
public void run() {
JFrame frame = new JFrame("Reverse Sample");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridLayout(3,3));
// for (int i=1; i<10; i++) {
for (int i=9; i>0; i--) {
JButton button = new JButton(Integer.toString(i));
frame.add(button, 0);
}
final Container contentPane = frame.getContentPane();
Comparator<Component> comp = new Comparator<Component>() {
public int compare(Component c1, Component c2) {
Component comps[] = contentPane.getComponents();
List list = Arrays.asList(comps);
int first = list.indexOf(c1);
int second = list.indexOf(c2);
return second - first;
}
};
FocusTraversalPolicy policy = new SortingFocusTraversalPolicy(comp);
frame.setFocusTraversalPolicy(policy);
frame.setSize(300, 200);
frame.setVisible(true);
}
};
EventQueue.invokeLater(runner);
}
}