example4_15.java

书中的例题

/* 演示复选框 */
import java.awt.*;
import java.awt.event.*;
class Example4_15 extends Frame implements ItemListener
{
  Checkbox c1,c2,c3;
  Example4_15(){
	setSize(200,200);
	setVisible(true);
    setLayout(new GridLayout(3,1));
    c1 = new Checkbox("one",null,true);
	c2 = new Checkbox("two");
	c3 = new Checkbox("three");
	add(c1);    add(c2);   add(c3);
    validate();
    c1.addItemListener(this);
    c2.addItemListener(this);
    c3.addItemListener(this);
  }
 public void itemStateChanged(ItemEvent ev){
   String state = "deselected";
   if (ev.getStateChange()==ItemEvent.SELECTED){
      state = "selected";
    } 
   System.out.println(ev.getItem()+" "+state);
  }
 public static void main(String[] args) 
	{  new Example4_15();	}
}