Drawing Graphics - Using paint() on Frame

Java Swing Tutorials - Herong's Tutorial Examples

∟Drawing Graphics - Using paint() on Frame

This section provides a tutorial example on how to override the paint() method in the javax.swing.JFrame class to draw graphics (a rectangle) on the frame window. This solution is not recommended.

Problem: I want to draw some graphics in a frame.

Solution 1: You can do this very easily by extending JFrame class to create your own frame class so that you can override the paint() method. The paint() method provides you a Graphics object, which will give you utility methods to draw various types of graphics. The following sample code, JFramePaint1.java, shows you how to do this.

/* JFramePaint1.java
 * Copyright (c) 1997-2018 HerongYang.com. All Rights Reserved.
 */
import java.awt.*;
import javax.swing.*;
public class JFramePaint1 {
   public static void main(String[] a) {
      MyJFrame f = new MyJFrame();
      f.setTitle("Drawing Graphics in Frames");
      f.setBounds(100,50,500,300);
      f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      f.setVisible(true);
   }
   static class MyJFrame extends JFrame {
      public void paint(Graphics g) {
         g.drawRect(20,10,100,60);
      }
   }
}

If you run this example, you will get:

Note 1: The paint() method is inherited by JFrame class from the Component class. It will be called whenever this component should be painted.

Note 2: If you look at the rectangle displayed on the frame, you will see that the origin of the drawing coordinates is located at the top left corner of the entire frame, including the title bar.

Note 3: By default, the paint() method provides transparent background, in JDK 1.4, 1.5 and 1.6. This is why you see a Web page showing up in the picture.