//file: HelloJava3.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class HelloJava3
extends JComponent
implements MouseMotionListener, ActionListener {
// Coordinates for the message
int messageX = 125, messageY = 95;
String theMessage;
JButton theButton;
// Current index into someColors
int colorIndex;
static Color[] someColors = { Color.black, Color.red,
Color.green, Color.blue, Color.magenta };
public HelloJava3(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) {
// Save the mouse coordinates and paint the message.
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.
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];
}
public static void main(String[] args) {
JFrame f = new JFrame("HelloJava3");
// Make the application exit when the window is closed.
f.addWindowListener(new WindowAdapter( ) {
public void windowClosing(WindowEvent we) { System.exit(0); }
});
f.setSize(300, 300);
f.getContentPane( ).add(new HelloJava3("Hello, Java!"));
f.setVisible(true);
}
}
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