Only let users input positive integers (no decimals or strings)?

Question

I know how to ask the user to input positive integers, but I don't know how approach the code to avoid an input error such as a decimal or string input.

  int seedValue;
  double angle, gunpowder;

  System.out.println("Please enter a positive integer seed value: ");
  seedValue = input.nextInt();

     while (seedValue <= 0) {  
        System.out.println("Please enter a positive integer seed value: ");
        seedValue = input.nextInt();
     }

     System.out.println("That target is " +
      threeDec.format(gen.nextDouble() * 1000) + "m away.");

Answer 1

This may be an approch:

• Read the input as a string value using Scanner.readLine();
• Try to convert the string to int using Integer.parseInt method. This method will throw a NumberFormatException in case the input string contains decimals and invalid digits.
• if the input value is parsed properly in previous step, then check for negative