Changing the Color of a Frame

We will fill in the actionPerformed() body so that clicking the button changes the color of the frame. To change the color of the frame, do this:

getContentPane().setBackground( Color.red )

A JFrame is a complicated object, made up of many parts. The frame's content pane is where components added to the frame are displayed. The getContentPane() method of the frame returns a reference to the content pane. The setBackground() method of the pane changes its background color.

Other pre-defined colors are Color.green, Color.blue, Color.yellow, and so on. (Look in your Java documentation under the class Color to find more.) Here is the interesting part of our program:

class ButtonFrame extends JFrame implements ActionListener
{
  JButton bChange ;

  // constructor   
  public ButtonFrame() 
  {
   . . . 
  }
   
  public void actionPerformed( ActionEvent evt)
  {
     ;
    repaint();  // ask the system to paint the screen.
  }
  
}

The repaint() will be explained in the next page.