java - 使用 if else 语句进行 JOptionPane 输入验证

Question

我想当用户输入一个不超过 100 的非正整数时，它会显示一条错误消息，如果输入正确，用户将再次输入，然后继续执行 if/else 语句。

import java.util.Scanner;
import javax.swing.JOptionPane;

public class Culminating {

    public static void main(String[] args) {
          Scanner  in = new Scanner (System.in);
       JOptionPane.showMessageDialog(null, "WELCOME");
        String userInput = JOptionPane.showInputDialog("KINDLY ENTER YOUR GRADES");
       int num = Integer.parseInt(userInput);
      
       
       if (num>100)
     {
    JOptionPane.showMessageDialog(null, "ERROR: PLEASE ENTER UP TO 100 ONLY" ); 
    
     }  
       
       else if (num>93)
     {
    JOptionPane.showMessageDialog(null, "Letter Grade: " + " A " + "\n\nPoints: " + 4.0 ); 
     }  
       
    else if (num > 90 )
    {
    JOptionPane.showMessageDialog(null, "Letter Grade: " +" A- " + "\n\nPoints: " + 3.7 ); 
    }
    
    else if (num> 87){
    JOptionPane.showMessageDialog(null, "Letter Grade: " + " B+ " + "\n\nPoints: " + 3.3 ); 
    }
       
    else if (num> 83){
    JOptionPane.showMessageDialog(null, "Letter Grade: " + " B " + "\n\nPoints: " + 3.0 ); 
    }
       
    else if (num>80){
    JOptionPane.showMessageDialog(null, "Letter Grade: " + " B- " + "\n\nPoints: " + 2.7 ); 
    }
       
    else if (num>77){
   JOptionPane.showMessageDialog(null, "Letter Grade: " + " C+ " + "\n\nPoints: " + 2.3 ); 
    }
    
    else if (num>73){
    JOptionPane.showMessageDialog(null, "Letter Grade: " + " C " + "\n\nPoints: " + 2.0 ); 
    }
       
    else if (num> 70){
    JOptionPane.showMessageDialog(null, "Letter Grade: " + " C- " + "\n\nPoints: " + 1.7 ); 
    }
    
    else if (num> 67){
    JOptionPane.showMessageDialog(null, "Letter Grade: " + " D+ " + "\n\nPoints: " + 1.3 ); 
    }
    
    else if (num>64){
    JOptionPane.showMessageDialog(null, "Letter Grade: " + " D " + "\n\nPoints: " + 1.0 ); 
    }
    
    else if (num<64){
    JOptionPane.showMessageDialog(null, "Letter Grade: " + " E " + "\n\nPoints: " + 0.0 ); 
    } 
       }
}

标签： javaswingvalidationinputjoptionpane