java 简单猜数字游戏

import java.awt.*;  
import java.awt.event.*;  
import javax.swing.*;  
  
public class lc4 implements ActionListener   {  
    int n=13;  
      
    JFrame jf=new JFrame("Example");  
          
    JTextField tf1=new JTextField(5);  
    JTextField tf2=new JTextField(15);  
      
    Label l=new Label("Please Input A Number:");  
      
    JButton b=new JButton("Close");  
  
    public static void main(String[] args) {  
        lc4 that=new lc4();  
        that.go();  
    }  
      
    public void go(){  
        jf.getContentPane().setLayout(new FlowLayout());  
          
        l.setBackground(Color.yellow);  
        tf1.setBackground(Color.green);  
        tf2.setBackground(Color.red);  
        b.setBackground(Color.gray);  
          
        jf.getContentPane().add(l);  
        jf.getContentPane().add(tf1);  
        jf.getContentPane().add(tf2);  
        jf.getContentPane().add(b);  
          
        tf1.addActionListener(this);  
        tf2.addActionListener(this);  
        b.addActionListener(this);  
          
        jf.pack();  
        jf.setVisible(true);  
    }  
    public void actionPerformed(ActionEvent e) {  
          
        if(n==Integer.valueOf(tf1.getText())){  
            tf2.setText("U R Right!");  
        }  
        else if(n<Integer.valueOf(tf1.getText())){  
            tf2.setText("Bigger!");  
        }  
        else{  
            tf2.setText("Smaller!");  
        }  
          
        if((JButton)e.getSource()==b){  
            System.exit(0);  
        }  
    }  
  
  
}