add lab11

lab/lab11/Question4/MyPanel.java

@@ -0,0 +1,46 @@
+import java.awt.Color;
+import java.awt.Graphics;
+import java.awt.Point;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.util.ArrayList;
+
+import javax.swing.JPanel;
+
+public class MyPanel extends JPanel {
+	private ArrayList<Point> point;
+
+	public MyPanel() {
+		point = new ArrayList<Point>();
+		// Anonymous class.
+		this.addMouseListener(new MouseAdapter() {
+			public void mouseClicked(MouseEvent e) {
+				// Check whether the left mouse button is clicked
+				if (e.getButton() == MouseEvent.BUTTON1) {
+					// store the point which been clicked
+					point.add(e.getPoint());
+					// get the coordinate
+					System.out.println("(" + e.getX() + "," + e.getY() + ")");
+				}
+
+			}
+		});
+	}
+
+	@Override
+	protected void paintComponent(Graphics g) {
+		// must clean the panel before drawing on it.
+		super.paintComponent(g);
+		g.setColor(Color.RED);
+		for (int i = 0; i < point.size(); i++) {
+			g.drawRect((int) point.get(i).getX(), (int) point.get(i).getY(), 1, 1);
+			if (i > 0) {
+				// connect next point
+				g.drawLine((int) point.get(i).getX(), (int) point.get(i).getY(),
+						(int) point.get(i - 1).getX(), (int) point.get(i - 1).getY());
+			}
+		}
+		// draw the red square
+		repaint();
+	}
+}