import java.awt.*; import java.awt.event.*; import javax.swing.*; public class HelloJava4 { public static void main( String[] args ) { JFrame frame = new JFrame( "HelloJava4" ); frame.add( new HelloComponent4("Hello Java!") ); frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE ); frame.setSize( 300, 300 ); frame.setVisible( true ); } } class HelloComponent4 extends JComponent implements MouseMotionListener, ActionListener, Runnable { 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 }; boolean blinkState; public HelloComponent4( String message ) { theMessage = message; theButton = new JButton("Change Color"); setLayout( new FlowLayout() ); add( theButton ); theButton.addActionListener( this ); addMouseMotionListener( this ); Thread t = new Thread( this ); t.start(); } public void paintComponent( Graphics g ) { g.setColor(blinkState ? getBackground() : currentColor( )); 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 ) { if ( e.getSource() == theButton ) changeColor(); } synchronized private void changeColor() { if (++colorIndex == someColors.length) colorIndex = 0; setForeground( currentColor() ); repaint(); } synchronized private Color currentColor( ) { return someColors[colorIndex]; } public void run( ) { try { while(true) { blinkState = !blinkState; // Toggle blinkState. repaint(); // Show the change. Thread.sleep(300); } } catch (InterruptedException ie) { } } }