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javajava.util.scannernumberformatexceptioninputmismatchexception

Asking for input after catching an exception


I want the user to enter a number which is scanned by the following code:

scanner.nextInt();

If a user enters a string instead, the program throws InputMismatchException, which is obvious. I want to catch the exception in such a way that the program prompts the user to enter an input until the user enters an integer value.

Scanner scanner = new Scanner(System.in);
while(true) {
    try {
        System.out.println("Please enter a number: ");
        int input = scanner.nextInt();
        System.out.println(input);
        //statements
        break;
    }
    catch(InputMismatchException | NumberFormatException ex ) {
        continue;
    }
}

This code creates an infinite loop if a string is entered.


Solution

  • Put Scanner scanner = new Scanner(System.in); within your while loop.

    Scanner scanner;
    while(true) {    
        try {
            System.out.println("Please enter a number: ");
            scanner = new Scanner(System.in);
            int input = scanner.nextInt();
            System.out.println(input);
            //statements
            break;
        }
        catch(InputMismatchException | NumberFormatException ex ) {
            System.out.println("I said a number...");
        }
    }