How to catch user input if it is anything else but int?

Question

so I am creating a TicTacToe game right now and don't really know how to handle anything else but a int. Let's say the user input is a string - the program would throw a error. I actually want it to catch it and say something like "this is not a number between 1 and 9". How can I do this?

int nextPlayerTurn= scan.nextInt();
            while (playerPosition.contains(nextPlayerTurn) ||computerPosition.contains(nextPlayerTurn)
                    || nextPlayerTurn>= 10 || nextPlayerTurn<= 0 ) {
                System.out.println("Position already taken! Please input a valid number (between 1 and 9) ");
                nextPlayerTurn= scan.nextInt();

Answer 1

If you use nextInt() and user enters a String, InputMismatchException will be thrown.

This is a way to handle it:

try {
    scan.nextInt();
}catch (InputMismatchException e) {
    System.err.println("this is not a number between 1 and 9");
}

Note that you will have to reuse nextInt() until the user enters an int

Answer 2

You can either use try catch method or if else conditions.

using if else ,

if(scan.hasNextInt()){
    int nextPlayerTurn = scan.nextInt();
    if(nextPlayerTurn < 0 || nextPlayerTurn > 10){
        System.out.println("this is not a number between 1 and 9");
    }else{
        //do something
    }
}else{
    System.out.println("this is not a number between 1 and 9");
}

using try catch ,

try{
    int nextPlayerTurn = scan.nextInt();
    if(nextPlayerTurn < 0 || nextPlayerTurn > 10){
        System.out.println("this is not a number between 1 and 9");
    }else{
        //do something
    }
}catch(InputMismatchException e){
    System.out.println("this is not a number between 1 and 9");
}

However, you can also use a method to check the InputMismatchException .
Also check Exception Handling Java