Mega Code Archive
Use the Event queue to retrieve event
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import java.awt.AWTEvent;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class EventQueuePanel extends JPanel implements ActionListener {
EventQueuePanel() {
JButton button = new JButton("Draw line");
add(button);
button.addActionListener(this);
}
public void actionPerformed(ActionEvent evt) {
Graphics g = getGraphics();
displayPrompt(g, "Click to chooose the first point");
Point p = getClick();
g.drawOval(p.x - 2, p.y - 2, 4, 4);
displayPrompt(g, "Click to choose the second point");
Point q = getClick();
g.drawOval(q.x - 2, q.y - 2, 4, 4);
g.drawLine(p.x, p.y, q.x, q.y);
displayPrompt(g, "Done! Press button the start again.");
g.dispose();
}
public void displayPrompt(Graphics g, String s) {
y += 20;
g.drawString(s, 0, y);
}
public Point getClick() {
EventQueue eq = Toolkit.getDefaultToolkit().getSystemEventQueue();
while (true) {
try {
AWTEvent evt = eq.getNextEvent();
if (evt.getID() == MouseEvent.MOUSE_PRESSED) {
MouseEvent mevt = (MouseEvent) evt;
Point p = mevt.getPoint();
Point top = getRootPane().getLocation();
p.x -= top.x;
p.y -= top.y;
return p;
}
} catch (InterruptedException e) {
}
}
}
private int y = 60;
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setTitle("EventQueueTest");
frame.setSize(300, 200);
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
Container contentPane = frame.getContentPane();
contentPane.add(new EventQueuePanel());
frame.show();
}
}
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