ButtonGroup & JRadioButton（单选框）

关于ButtonGroup和JRadioButton的应用

import java.awt.*;import javax.swing.*;public class JRadioButtonTest extends ButtonGroup{JRadioButtonTest(){JFrame f = new JFrame("单选框示例");//创建一个JFrame的对象Container contenPane = f.getContentPane();//创建一个内容面板容器contenPane.setLayout(new FlowLayout());//设置该容器的布局JPanel pl = new JPanel();//创建一个面板对象plpl.setLayout(new GridLayout(1 ,3));//设置该面板的布局管理器格式pl.setBorder(BorderFactory.createTitledBorder("选择你喜欢的城市"));//定义3个JRadioButton单选按钮JRadioButton r1 = new JRadioButton("北京");JRadioButton r2 = new JRadioButton("上海");JRadioButton r3 = new JRadioButton("青岛");ButtonGroup bg = new ButtonGroup();//创建一个ButtonGroup对象bg.add(r1);bg.add(r2);bg.add(r3);pl.add(r1);pl.add(r2);pl.add(r3);contenPane.add(pl);f.pack();f.setVisible(true);}public static void main(String[] args){JRadioButtonTest jbt = new JRadioButtonTest();}}