An OverlayLayout Example

Rather than contrive an example using the OverlayLayout manager,with an OverlayLayout manager running. You can type in the X- and Y-alignment values between 0.0 and 1.0 into text fields along the bottom. The text fields are organized as X and Y alignments for each of the three buttons (B1, B2, and B3 respectively). Click the Update button. The buttons in the floating panel rearrange themselves according to the values you enter. The gridlines show the bounds of the panel and its center. Try changing several of the values; this will give you an idea of how this layout manager might be used.

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

public class OverlayTest extends JFrame {

	public OverlayTest() {
		super("OverlayLayout Test");
		setSize(500, 300);
		setDefaultCloseOperation(EXIT_ON_CLOSE);

		final Container c = getContentPane();
		c.setLayout(new GridBagLayout());

		final JPanel p1 = new GridPanel();
		final OverlayLayout overlay = new OverlayLayout(p1);
		p1.setLayout(overlay);

		final JButton jb1 = new JButton("B1");
		final JButton jb2 = new JButton("B2");
		final JButton jb3 = new JButton("B3");

		Dimension b1 = new Dimension(60, 50);
		Dimension b2 = new Dimension(80, 40);
		Dimension b3 = new Dimension(100, 60);

		jb1.setMinimumSize(b1);
		jb1.setMaximumSize(b1);
		jb1.setPreferredSize(b1);
		jb2.setMinimumSize(b2);
		jb2.setMaximumSize(b2);
		jb2.setPreferredSize(b2);
		jb3.setMinimumSize(b3);
		jb3.setMaximumSize(b3);
		jb3.setPreferredSize(b3);

		SimpleReporter reporter = new SimpleReporter();
		jb1.addActionListener(reporter);
		jb2.addActionListener(reporter);
		jb3.addActionListener(reporter);

		p1.add(jb1);
		p1.add(jb2);
		p1.add(jb3);

		JPanel p2 = new JPanel();
		p2.setLayout(new GridLayout(2, 6));
		p2.add(new JLabel("B1 X", JLabel.CENTER));
		p2.add(new JLabel("B1 Y", JLabel.CENTER));
		p2.add(new JLabel("B2 X", JLabel.CENTER));
		p2.add(new JLabel("B2 Y", JLabel.CENTER));
		p2.add(new JLabel("B3 X", JLabel.CENTER));
		p2.add(new JLabel("B3 Y", JLabel.CENTER));
		p2.add(new JLabel(""));

		final JTextField x1 = new JTextField("0.0", 4); // B1 x alignment
		final JTextField y1 = new JTextField("0.0", 4); // B1 y alignment
		final JTextField x2 = new JTextField("0.0", 4);
		final JTextField y2 = new JTextField("0.0", 4);
		final JTextField x3 = new JTextField("0.0", 4);
		final JTextField y3 = new JTextField("0.0", 4);

		p2.add(x1);
		p2.add(y1);
		p2.add(x2);
		p2.add(y2);
		p2.add(x3);
		p2.add(y3);

		GridBagConstraints constraints = new GridBagConstraints();
		c.add(p1, constraints);

		constraints.gridx = 1;
		JButton updateButton = new JButton("Update");
		updateButton.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent ae) {
			jb1.setAlignmentX(Float.valueOf(x1.getText().trim()).floatValue());
			jb1.setAlignmentY(Float.valueOf(y1.getText().trim()).floatValue());
			jb2.setAlignmentX(Float.valueOf(x2.getText().trim()).floatValue());
			jb2.setAlignmentY(Float.valueOf(y2.getText().trim()).floatValue());
			jb3.setAlignmentX(Float.valueOf(x3.getText().trim()).floatValue());
			jb3.setAlignmentY(Float.valueOf(y3.getText().trim()).floatValue());

				p1.revalidate();
			}
		});
		c.add(updateButton, constraints);

		constraints.gridx = 0;
		constraints.gridy = 1;
		constraints.gridwidth = 2;
		c.add(p2, constraints);
	}

	public static void main(String args[]) {
		OverlayTest ot = new OverlayTest();
		ot.setVisible(true);
	}

	public class SimpleReporter implements ActionListener {
		public void actionPerformed(ActionEvent ae) {
			System.out.println(ae.getActionCommand());
		}
	}

	public class GridPanel extends JPanel {
		public void paint(Graphics g) {
			super.paint(g);
			int w = getSize().width;
			int h = getSize().height;

			g.setColor(Color.red);
			g.drawRect(0, 0, w - 1, h - 1);
			g.drawLine(w / 2, 0, w / 2, h);
			g.drawLine(0, h / 2, w, h / 2);
		}
	}
}