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Introduction to Web Programming
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:

    [Example]

    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);
        }
      }
    
    
    

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