照抄书上一段代码 2 个错!!!!!
import java.awt.*;
import java.awt.event.*;
class box extends Frame
implements ItemListener
{
Checkbox b1,b2,b3,b4;
TextField tf;
box(String t)
{
super(t);
setLayout(new FlowLayout());
b1=new Checkbox("A",false);
b2=new Checkbox("B",false);
b3=new Checkbox("C",false);
b4=new Checkbox("D",false);
add(b1); add(b2); add(b3); add(b4);
b1.addItemListener(this);
b2.addItemListener(this);
b3.addItemListener(this);
b4.addItemListener(this);
tf=new TextField(20);
add(tf);
setSize(40,100);
}
public void itemStateChanged(ItemEvent event)
{
tf.setText("Checkbox "+event.getItemSelectable().getLabel());
}
addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){ System.exit(0);}
});
public static void main(String args[])
{
box m=new box("box");
m.show();
}
}