import java.awt.*; import java.awt.event.*; import javax.swing.*; public class HelloJava3 { public static void main( String[] args ) { JFrame frame = new JFrame( "HelloJava3" ); frame.add( new HelloComponent3("Hello Java!") ); frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE ); frame.setSize( 300, 300 ); frame.setVisible( true ); } } class HelloComponent3 extends JComponent implements MouseMotionListener, ActionListener { String theMessage; int messageX = 125, messageY = 95; // Coordinates of the message JButton theButton; int colorIndex; // Current index into someColors static Color[] someColors = { Color.black, Color.red, Color.green, Color.blue, Color.magenta }; public HelloComponent3( String message ) { theMessage = message; theButton = new JButton("Change Color"); setLayout( new FlowLayout() ); add( theButton ); theButton.addActionListener( this ); addMouseMotionListener( this ); } public void paintComponent( Graphics g ) { g.drawString(theMessage, messageX, messageY); } public void mouseDragged( MouseEvent e ) { messageX = e.getX(); messageY = e.getY(); repaint(); } public void mouseMoved( MouseEvent e ) {} public void actionPerformed( ActionEvent e ) { // Did somebody push our button? if (e.getSource() == theButton) changeColor(); } synchronized private void changeColor() { // Change the index to the next color, awkwardly. if (++colorIndex == someColors.length) colorIndex = 0; setForeground(currentColor( )); // Use the new color. repaint( ); // Paint again so we can see the change. } synchronized private Color currentColor() { return someColors[colorIndex]; } }