Catch块串/号验证

• Z时代
• 2024-01-10
• 分类：问答

在catch块我想打印输入有效的卡没有，如果有人进入 字符串或数字小于13或大于16Catch块串/号验证

我刚才说NumberFormatException的，但它什么都不做如果我输入一个字符串或数字小于13或大于16的数字。

如何在这里有例外？此代码仅用于验证信用卡。我只是需要试试catch块的帮助。

import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import javax.swing.BoxLayout; 
import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.JTextField; 
//CreditCard class 
public class CreditCard { 
    //Variable declaration 
    private JFrame frame; 
    private JPanel panel; 
    private JTextField textField; 
    private JLabel label; 
    private JLabel resLabel; 
    private JButton validateBtn; 
    //Constructor 
    public CreditCard() { 
     frame = new JFrame("Credit Card Details"); 
     frame.setSize(350, 350); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     // create a new panel and add the frame to the panel. 
     panel = new JPanel(); 
     frame.add(panel); 
     panel.setLayout(null); 
     // add label 
     label = new JLabel("Enter Credit Card No."); 
     label.setBounds(10, 20, 165, 25); 
     panel.add(label); 
     // add input text 
     textField = new JTextField(16); 
     textField.setBounds(10, 50, 165, 25); 
     panel.add(textField); 
     // create a validation button 
     validateBtn = new JButton("Validate"); 
     validateBtn.setBounds(10, 80, 80, 25); 
     panel.add(validateBtn); 
     frame.setVisible(true); 
     // set label as valid or invalid 
     resLabel = new JLabel(); 
     resLabel.setBounds(180, 50, 265, 25); 
     panel.add(resLabel); 
     // add event listener 
     validateBtn.addActionListener(new ActionListener() { 
      @Override 
      public void actionPerformed(ActionEvent e) { 
       try { 
       String text = textField.getText(); 
       if (text.length() < 13 || text.length() > 16) { 
        resLabel.setText("Entered Value Must Be Between 13-16 Chars"); 
        return; 
       } 
       boolean isValid = validateText(text); 
       if(isValid) 
        resLabel.setText("Credit Card is Valid"); 
       else 
        resLabel.setText("Credit Card is Invalid"); 
       }catch(NumberFormatException f){ 
        System.out.println("Enter Valid Card Number"); 
       } 
      } 
      private boolean validateText(String text) { 
       int rSum = 0, lSum = 0; 
       for (int i = text.length() - 2; i >= 0; i -= 2) { 
        if (!Character.isDigit(text.charAt(i))) 
         return false; 
        int currentNum = Character.getNumericValue(text.charAt(i)); 
        currentNum *= 2; 
        if (currentNum > 9) { 
         int tempSum = 0; 
         while (currentNum >= 10) { 
          tempSum += currentNum % 10; 
          currentNum /= 10; 
         } 
         tempSum += currentNum; 
         currentNum = tempSum; 
        } 
        rSum += currentNum; 
       } 
       System.out.println(rSum); 
       for (int i = text.length() - 1; i >= 0; i -= 2) { 
        if (!Character.isDigit(text.charAt(i))) 
         return false; 
        int currentNum = Character.getNumericValue(text.charAt(i)); 
        lSum += currentNum; 
       } 
       System.out.println(lSum); 
       int totalSum = lSum + rSum; 
       if (totalSum % 10 == 0) 
        return true; 
       return false; 
      } 
     }); 
    } 
} 

回答：

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