Focus Traversal Demo in SWT

[Java Tip]

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.events.KeyListener;
import org.eclipse.swt.events.TraverseEvent;
import org.eclipse.swt.events.TraverseListener;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.RowLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.List;
import org.eclipse.swt.widgets.Shell;

public class FocusTraversal {
  Display display = new Display();
  Shell shell = new Shell(display);

  public FocusTraversal() {
    init();

    shell.pack();
    shell.open();
    //textUser.forceFocus();

    // Set up the event loop.
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        // If no more entries in event queue
        display.sleep();
      }
    }

    display.dispose();
  }

  private void init() {
    shell.setLayout(new RowLayout());
    Composite composite1 = new Composite(shell, SWT.BORDER);
    composite1.setLayout(new RowLayout());
    composite1.setBackground(display.getSystemColor(SWT.COLOR_WHITE));
    Button button1 = new Button(composite1, SWT.PUSH);
    button1.setText("Button1");
    List list = new List(composite1, SWT.MULTI | SWT.BORDER);
    list.setItems(new String[]{"Item-1", "Item-2", "Item-3"});

    Button radioButton1 = new Button(composite1, SWT.RADIO);
    radioButton1.setText("radio-1");
    Button radioButton2 = new Button(composite1, SWT.RADIO);
    radioButton2.setText("radio-2");
    Composite composite2 = new Composite(shell, SWT.BORDER);
    composite2.setLayout(new RowLayout());
    composite2.setBackground(display.getSystemColor(SWT.COLOR_GREEN));
    Button button2 = new Button(composite2, SWT.PUSH);
    button2.setText("Button2");
    final Canvas canvas = new Canvas(composite2, SWT.NULL);
    canvas.setSize(50, 50);
    canvas.setBackground(display.getSystemColor(SWT.COLOR_YELLOW));

    Combo combo = new Combo(composite2, SWT.DROP_DOWN);
    combo.add("combo");
    combo.select(0);
    canvas.addKeyListener(new KeyListener() {
      public void keyPressed(KeyEvent e) {
        GC gc = new GC(canvas);
        // Erase background first. 
        Rectangle rect = canvas.getClientArea();
        gc.fillRectangle(rect.x, rect.y, rect.width, rect.height);
        Font font = new Font(display, "Arial", 32, SWT.BOLD );
        gc.setFont(font);
        gc.drawString("" + e.character, 15, 10);
        gc.dispose();
        font.dispose();
      }

      public void keyReleased(KeyEvent e) {
      }
    });
    canvas.addTraverseListener(new TraverseListener() {
      public void keyTraversed(TraverseEvent e) {
        if(e.detail == SWT.TRAVERSE_TAB_NEXT ||
            e.detail == SWT.TRAVERSE_TAB_PREVIOUS)
          e.doit = true;
      }
    });
    composite1.setTabList(new Control[]{button1, list});
    composite2.setTabList(new Control[]{button2, canvas, combo});
    shell.setTabList(new Control[]{composite2, composite1});
  }

  public static void main(String[] args) {
    new FocusTraversal();
  }
}