eventhandlingdemo5.java

JAVA程序设计课程中各章节的程序实例。

/**
*A item event handling program 
*Choice and Checkbox objects generate "item events"
*that can be processed by any ItemListener object.
*2004.12.29. xhcprince
*/

import java.awt.*;
import java.awt.event.*;

public class EventHandlingDemo5 extends Frame implements ItemListener
{
	private Checkbox checkbox;
	private Label label;
	
	public EventHandlingDemo5(String strName)
	{
		super(strName);
		
		Panel p = new Panel();
		
		checkbox = new Checkbox("Be taller!",null,true);
		
		p.setLayout(new FlowLayout());
		p.add(checkbox);
		
		label = new Label("I can and I will:)",Label.CENTER);
		add(p);
		add(label,"South");
		
		checkbox.addItemListener(this);
	}
	
	public void itemStateChanged(ItemEvent e)
	{
	/*--------------------------------------------------------------------------
		Called just after a state change in the listeded-to component
	--------------------------------------------------------------------------*/
		if(e.getStateChange() == ItemEvent.SELECTED)
		{
			label.setVisible(true);
			label.repaint();
		}
		
		else
		{
			label.setVisible(false);
		}
	}

	public static void main(String args[])
	{
		EventHandlingDemo5 obj = new EventHandlingDemo5("Tall!");
		
		obj.setSize(300,300);
		obj.setVisible(true);
	}
}