Exercise Eight

Exercise Eight

• Okay, let's try a simple example of using events. Try to create a program which will respond to button events. In the following example, a panel is colored differently each time the user clicks the button:
  

  import java.awt.*;
  
  public class EventExample extends Panel
    {
    public Panel     displayPanel;
    public Button    colorButton;
    public Color[]   colors = {Color.black, 
  			     Color.red, 
  			     Color.yellow,
  			     Color.green};
    private int	   counter = 0;
  
    public EventExample()
      {
      setLayout(new BorderLayout());
      displayPanel = new Panel();
      add("Center", displayPanel);
      colorButton = new Button("Change Color");
      add("South", colorButton);
      }
  
    public static void main(String[] args)
      {
      Frame baseFrame = new Frame();
      EventExample ee = new EventExample();
      baseFrame.add("Center", ee);
      baseFrame.reshape(10,10,200,200);
      baseFrame.setTitle("Event Example");
      baseFrame.show();
      }
  
    public boolean action(Event evt, Object obj)
      {
      displayPanel.setBackground(colors[counter]);
      if (counter <=2)     
         counter++;
      else
         counter =0;
      return super.action(evt, obj);
      }
    }
  

Event Modifiers
Table of Contents
Beans Events