import java.awt.AWTEvent;
import java.awt.EventQueue;
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 javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main extends JPanel implements ActionListener {
Main() {
JButton button = new JButton("Click to chooose the first point");
add(button);
button.addActionListener(this);
}
public void actionPerformed(ActionEvent evt) {
Graphics g = getGraphics();
Point p = getClick();
g.drawOval(p.x - 2, p.y - 2, 4, 4);
Point q = getClick();
g.drawOval(q.x - 2, q.y - 2, 4, 4);
g.drawLine(p.x, p.y, q.x, q.y);
g.dispose();
}
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) {
}
}
}
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setSize(300, 200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new Main());
frame.setVisible(true);
}
}