actionListener

package 实验四;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
//切换按钮的文字
public class label_3 extends JFrame {
	/**
	 * @param
	 */
		private static final long serialVersionUID=1L;
		JButton b1 =new JButton("切换");
		JRadioButton r1=new JRadioButton ("普通");
		JRadioButton r2=new JRadioButton ("黑体");
		JRadioButton r3=new JRadioButton ("斜体");
		ButtonGroup group=new ButtonGroup();
		
		
		
		public label_3(){
			setTitle("切换");		//给窗口命名
			getContentPane().setLayout(new FlowLayout(1,10,20));
			getContentPane().add(b1);
			group.add(r1);				//将单选框添加至组中
			group.add(r2);
			group.add(r3);
			add(r1);
			add(r2);
			add(r3);
			Actionevent A1=new Actionevent(Font.PLAIN);    //给每个字体构造一个对象，并将其设置为按钮监听器
			Actionevent A2=new Actionevent(Font.BOLD);
			Actionevent A3=new Actionevent(Font.ITALIC);
			r1.addActionListener(A1);
			r2.addActionListener(A2);
			r3.addActionListener(A3);
			this.setSize(800, 300);
		}
	    //@Override
		class Actionevent implements ActionListener{
			private int f;
			Actionevent(int x){
				this.f=x;
			}
	    	public void actionPerformed(ActionEvent e){
	    		if(f==0) b1.setFont(new Font(b1.getName(),Font.PLAIN,20));   //如何不更改字号->如何获取Button文字的大小
	    		else if(f==1) b1.setFont(new Font(b1.getName(),Font.BOLD,20));
	    		else if(f==2) b1.setFont(new Font(b1.getName(),Font.ITALIC,20));
	    	}
		}
		
		
		public static void main(String[] args){
			label_3 frame =new label_3();
			frame.setDefaultCloseOperation(3);
			frame.setResizable(false);
			//frame.pack();
			frame.setVisible(true);
	}
}