String to int failed ̣(can you show me what's wrong and how to fix it? )

Question

1.00/5 (1 vote)

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import java.util.Scanner;

public class Menu {
     public static Scanner scanner = new Scanner(System.in);
    
    public static int inputInt(String msg){
        int data;
            System.out.print( msg);
            data= Integer.parseInt(scanner.nextLine());
      
        return data;
    }
    public static void main(String[] args) {
        y1 f1 = new y1();
        y2 f2 = new y2();
        y3 f3 = new y3();

        int option = -1;
        do {
            System.out.println("----- MENU -----");
            System.out.println("1. y1");
            System.out.println("2. y2");
            System.out.println("3. y3");
            System.out.println("0. Exists");
 
            option = inputInt("Enter your choice: ");

            switch (option) {
                case 1:
                    f1.findS();
                    break;
                case 2:
                    
                    f2.check();
                    break;
                case 3:                    
                    f3.seriesOfPrimeNum();
                    break;
                case 0:
                    System.out.println("Exist program. Goodbye!!");
                    break;
                default:
                    System.out.println("Wrong input ! Please enter again ");
            }
        }  while (option != 0);
    }
}

What I have tried:

When I enter a character or string for option it outputs an error, whereas in the inputInt function I convert String to Int already

Posted 18-Jul-23 5:08am

i want to code better

Updated 18-Jul-23 5:30am

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Richard MacCutchan 18-Jul-23 11:33am

I just tried that and it seems to work fine. You need to provide more details.

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OriginalGriff · Accepted Answer · 2023-07-18T05:30:00

Because the string or character you entered isn't a numeric digit: if it isn't, it can't be parsed to a number!
Put a while loop around the print and parseInt calls, and a try ... catch block as well. Move your return to after the parseInt call, and it will loop until the user enters a number.

Java

while(true) {
   try {
      ...your stuff...
      return data;
   }
   catch(Exception e) {}
}

Also, see here: Java.util.Scanner.nextInt() Method | Tutorialspoint[^]
Replace this:

Java

data= Integer.parseInt(scanner.nextLine());

With this:

Java

data= scanner.nextInt();

And let the system do the work.

String to int failed ̣(can you show me what's wrong and how to fix it? )

1 solution

Solution 1

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