CheckBox的监听器怎么使用？？

Question

我不太会用，给我举一个例子吧，看API文档，按照我自己的理解方式去做不行。

Answer 1

import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;
import java.awt.font.FontRenderContext;
import java.awt.geom.AffineTransform;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import javax.swing.table.*;
import java.util.*;
/**
 * 2011-6-5 0:33:50
 * @author Administrator
 */
public class TJComboBox2 {
    JFrame frame;
    Container contentPane;
    JComboBox comboBox;
    JLabel label;
    public TJComboBox2(){
        frame=new JFrame("ComboBox测试");
        contentPane=frame.getContentPane();
        contentPane.setLayout(new GridBagLayout());
        setLabel();
        add(contentPane, label, 0, 0, 1, 1);
        setComboBox();
        add(contentPane, comboBox, 0, 1, 1, 0);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
    public void setLabel(){
        label=new JLabel();
        label.setText("Swing 目前字体大小:"+label.getFont().getSize());
        label.setHorizontalAlignment(JLabel.CENTER);
        label.setVerticalAlignment(JLabel.CENTER);
        label.setBackground(Color.red);
        label.setForeground(Color.green);
        label.setOpaque(true);
        Font font=new Font("楷体",Font.PLAIN,100);
//        label.setFont(font);
        String str=new String("Swing 目前字体大小:100");
        Rectangle2D rect=font.getStringBounds(str, new FontRenderContext(new AffineTransform(), true, true));
        label.setPreferredSize(new Dimension((int)rect.getWidth(),(int)rect.getHeight()));
    }
    public void setComboBox(){
        Integer size[]={10,11,12,13,14,15,20,30,40,50};
        DefaultComboBoxModel model=new DefaultComboBoxModel(size);
        comboBox=new JComboBox(model);
        comboBox.addItemListener(new ItemListener(){
            Object lastValue;
            public void itemStateChanged(ItemEvent e) {
                Object o=comboBox.getSelectedItem();
                if(lastValue!=null){
                    if(lastValue.equals(o)){
                        return;
                    }
                }
                lastValue=o;
                int size;
                if(o instanceof String){
                    try{
                        size=Integer.parseInt((String)o);
                    }catch(NumberFormatException nfe){
                        JOptionPane.showMessageDialog(frame, "输入的大小不是纯数字", "错误提示", JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                }
                else{
                    size=(Integer)o;
                }
                DefaultComboBoxModel model=(DefaultComboBoxModel)comboBox.getModel();
                if(model.getIndexOf(size)==-1){
                    model.addElement(size);
                }
                label.setText("Swing 目前字体大小:"+size);
                label.setFont(new Font(label.getFont().getName(),label.getFont().getStyle(),size));
            }
        });
        comboBox.setEditable(true);
        ComboBoxEditor editor=comboBox.getEditor();
        comboBox.configureEditor(editor, "请输入或者直接选择");
    }
    public void add(Container main,Container child,int gridx,int gridy,double weightx,double weighty){
        GridBagConstraints c=new GridBagConstraints();
        c.gridx=gridx;
        c.gridy=gridy;
        c.gridwidth=1;
        c.gridheight=1;
        c.weightx=weightx;
        c.weighty=weighty;
        c.fill=GridBagConstraints.BOTH;
        main.add(child,c);
    }
    public static void main(String args[]){
        new TJComboBox2();
    }
}