Drawing Graphics - Using paint() on Component

Java Swing Tutorials - Herong's Tutorial Examples

∟Drawing Graphics - Using paint() on Component

This section provides a tutorial example on how to override the paint() method in the javax.swing.Component class to draw graphics (a rectangle) and add the component to the content pane of the frame window.

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

Solution 2: Obviously, solution 1 is not so ideal, because we are drawing on the UI element of the frame itself. To draw graphics only in the content area of the frame, we can create a new component with its own paint() method and add it to the content pane of the frame. The following sample code, JFramePaint2.java, shows you how to do this.

/* JFramePaint2.java
 * Copyright (c) 1997-2018 HerongYang.com. All Rights Reserved.
 */
import java.awt.*;
import javax.swing.*;
public class JFramePaint2 {
   public static void main(String[] a) {
      JFrame f = new JFrame();
      f.setTitle("Drawing Graphics in a Frame"
         +" by Adding a Component");
      f.setBounds(100,50,500,300);
      f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      f.getContentPane().add(new MyComponent());
      f.setVisible(true);
   }
   static class MyComponent extends JComponent {
    b  public void paint(Graphics g) {
         g.drawRect(20,10,100,60);
      }
   }
}

If you run this example, you will get:

Note 1: Since no size and location is given to the new added component, it takes the entire area of the content pane, which is the entire area of the frame without the title bar area.