怎样在上面加一个捕捉异常的代码，如输入字母a会出现错误，应该怎样解决

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
//导入相应的包

public class game {
public static int couBut = 0;
//创建一个公共整形coutBut用户控制输入次数
public static void main(String[] args) {
JFrame frame = new JFrame("猜数字游戏");
frame.setSize(400, 200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel();
frame.add(panel);
placeComponents(panel);
frame.setVisible(true);
}

private static void placeComponents(JPanel panel) {        
    panel.setLayout(null);
    JLabel userLabel = new JLabel("请输入一个100内整数进行试猜，注意允许竞猜的最大次数是5次！", SwingConstants.CENTER);       
    userLabel.setBounds(10,20,360,25);        
    panel.add(userLabel);      
   JTextField userText = new JTextField(20);
    userText.setBounds(160,50,80,25);
    panel.add(userText);
    userText.setHorizontalAlignment(JTextField.CENTER);       
    JButton loginButton = new JButton("确定");
    loginButton.setBounds(160, 80, 80, 25);
    panel.add(loginButton);            
  loginButton.addActionListener(new ActionListener() {          
         public void actionPerformed(ActionEvent actionEvent) {              
           couBut += 1;             
           int guessnum;
           guessnum = Integer.parseInt(userText.getText());
    int realnumber = (int)(Math.random()*100+1);
    if(couBut > 4 && couBut < 6){
                userLabel.setText("您猜 5 次了都没猜对，这不怪你，程序就是这么扣！");
                    userText.setText("");
            }
            else if(couBut > 4){
                    System.exit(0);
             }
     else if(guessnum > realnumber){
        userLabel.setText("您输入的数字太大了，请重新竞猜！");
        userText.setText("");
      }
     else if(guessnum < realnumber){
        userLabel.setText("您输入的数字太小了，请重新竞猜！");
        userText.setText("");
     }
     else{
        userLabel.se

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
//导入相应的包

public class game {
    public static int couBut = 0;

    //创建一个公共整形coutBut用户控制输入次数
    public static void main(String[] args) {
        JFrame frame = new JFrame("猜数字游戏");
        frame.setSize(400, 200);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel panel = new JPanel();
        frame.add(panel);
        placeComponents(panel);
        frame.setVisible(true);
    }

    private static void placeComponents(JPanel panel) {
        panel.setLayout(null);
        JLabel userLabel = new JLabel("请输入一个100内整数进行试猜，注意允许竞猜的最大次数是5次！", SwingConstants.CENTER);
        userLabel.setBounds(10, 20, 360, 25);
        panel.add(userLabel);
        JTextField userText = new JTextField(20);
        userText.setBounds(160, 50, 80, 25);
        panel.add(userText);
        userText.setHorizontalAlignment(JTextField.CENTER);
        JButton loginButton = new JButton("确定");
        loginButton.setBounds(160, 80, 80, 25);
        panel.add(loginButton);
        loginButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent actionEvent) {
                couBut += 1;
                int guessnum = 0;
                while(true){
                    try{
                        guessnum = Integer.parseInt(userText.getText());
                        break;
                    }catch (Exception e){
                        JOptionPane.showMessageDialog(null, "输入的不是数字，请重新输入！", "提示框",JOptionPane.INFORMATION_MESSAGE);
                        userText.setText("");
                        return;
                    }
                }
                int realnumber = (int) (Math.random() * 100 + 1);
                if (couBut > 4 && couBut < 6) {
                    userLabel.setText("您猜 5 次了都没猜对，这不怪你，程序就是这么扣！");
                    userText.setText("");
                } else if (couBut > 4) {
                    System.exit(0);
                } else if (guessnum > realnumber) {
                    userLabel.setText("您输入的数字太大了，请重新竞猜！");
                    userText.setText("");
                } else if (guessnum < realnumber) {
                    userLabel.setText("您输入的数字太小了，请重新竞猜！");
                    userText.setText("");
                }
            }
        });
    }
}

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