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【第18章：图形界面】_单选钮：JRadioButton

发布时间：2021-01-17 17:09:45编辑：雪饮阅读（）

 单选按钮的实现

用javax.swing.JRadioButton可以实现单选按钮
import java.awt.Container ;
import java.awt.GridLayout ;
import javax.swing.JFrame ;
import javax.swing.JPanel ;
import javax.swing.JRadioButton ;
import javax.swing.BorderFactory ;
class MyRadio{
       private JFrame frame = new JFrame("Welcome TO kasumi") ;
       private Container cont = frame.getContentPane() ;
       private JRadioButton jrb1 = new JRadioButton("kasumi") ;
       private JRadioButton jrb2 = new JRadioButton("snowDrink") ;
       private JRadioButton jrb3 = new JRadioButton("ayane") ;
       private JPanel pan = new JPanel() ;
       public MyRadio(){
              // 设置一个边框的显示条
              pan.setBorder(BorderFactory.createTitledBorder("请选择你喜欢的角色")) ;
              pan.setLayout(new GridLayout(1,3)) ;
              pan.add(this.jrb1) ;
              pan.add(this.jrb2) ;
              pan.add(this.jrb3) ;
              cont.add(pan) ;
              this.frame.setSize(300,80) ;
              this.frame.setVisible(true) ;
       }
};
public class TestJava{
       public static void main(String args[]){
              new MyRadio() ;
       }
}

按钮组的实现
使用javax.swing.ButtonGroup可以实现单选按钮的可用性，上面实现的单选按钮仅空有样式却没有功效，可以每个选项都能选择，这和html中的单选是一样的，必须设定每个单选项属于同一个按钮组才能真正实现单选。
import java.awt.Container ;
import java.awt.GridLayout ;
import javax.swing.JFrame ;
import javax.swing.JPanel ;
import javax.swing.JRadioButton ;
import javax.swing.ButtonGroup ;
import javax.swing.BorderFactory ;
class MyRadio{
       private JFrame frame = new JFrame("Welcome TO kasumi") ;
       private Container cont = frame.getContentPane() ;
       private JRadioButton jrb1 = new JRadioButton("kasumi") ;
       private JRadioButton jrb2 = new JRadioButton("snowDrink") ;
       private JRadioButton jrb3 = new JRadioButton("ayane") ;
       private JPanel pan = new JPanel() ;
       public MyRadio(){
              pan.setBorder(BorderFactory.createTitledBorder("请选择你喜欢的角色")) ;
              pan.setLayout(new GridLayout(1,3)) ;
              pan.add(this.jrb1) ;
              pan.add(this.jrb2) ;
              pan.add(this.jrb3) ;
              ButtonGroup group = new ButtonGroup() ;
              group.add(this.jrb1) ;
              group.add(this.jrb2) ;
              group.add(this.jrb3) ;
              cont.add(pan) ;
              this.frame.setSize(300,80) ;
              this.frame.setVisible(true) ;
       }
};
public class TestJava{
       public static void main(String args[]){
              new MyRadio() ;
       }
}

单选按钮切换事件监听
实现java.awt.event.ItemListener接口的itemStateChanged即可对单选按钮切换事件进行监听
import java.awt.GridLayout ;
import java.awt.event.ItemListener ;
import java.awt.event.ItemEvent ;
import javax.swing.JFrame ;
import javax.swing.JRadioButton ;
import javax.swing.ButtonGroup ;
import javax.swing.ImageIcon ;
import javax.swing.JLabel ;
import javax.swing.JPanel ;
class MyRadio implements ItemListener{
       //设置默认选中项图片
       private JLabel jlab = new JLabel("",new ImageIcon("d:/8.jpg"),JLabel.CENTER);
       //图片单选框
       private JRadioButton kasumijb = new JRadioButton("kasumi",new ImageIcon("d:/8.jpg"),true) ;
       private JRadioButton momijijb = new JRadioButton("momiji",new ImageIcon("d:/9.jpg"),false) ;
       public MyRadio(){
              JFrame frame = new JFrame("Welcome TO kasumi") ;
              frame.setLayout(new GridLayout(2,1)) ;
              //图片单选框加入到单选按钮组
              ButtonGroup group = new ButtonGroup() ;
              group.add(kasumijb) ;
              group.add(momijijb) ;
              //监听这两个单选按钮
              kasumijb.addItemListener(this) ;
              momijijb.addItemListener(this) ;
             
              JPanel pan = new JPanel() ;
              pan.setLayout(new GridLayout(1,2)) ;
              pan.add(kasumijb);
              pan.add(momijijb);
             
              frame.add(pan);
              frame.add(jlab);
             
              frame.setSize(300,80) ;
              frame.setVisible(true) ;
       }
       //实现接口的itemStateChanged方法用于接收单选按钮切换逻辑处理
       public void itemStateChanged(ItemEvent e){
              if(e.getSource()==kasumijb){
                     jlab.setIcon(kasumijb.getIcon());
              }
              if(e.getSource()==momijijb){
                     jlab.setIcon(momijijb.getIcon());
              }
       }
};
public class TestJava{
       public static void main(String args[]){
              new MyRadio() ;
       }
}