How to check if user's input is a number with scanner.hasNextDouble?

I have to write the code to (first) check if the user's input is a number, if it isn't, print "Invalid input." (Second) If it's a number, check again if it's a non-zero number, print "Invalid input" again if it isn't.

I've got the second part figured out but I can't seem to have the first part working aka check if the input is a number. I would have to enter 2 inputs instead of one and if the first input is not a number, java would give me an error instead of printing "Invalid input".

    Scanner stdin = new Scanner(System.in);

    System.out.println("Enter a non-zero number");
    double number = stdin.nextDouble();

    if (stdin.hasNextDouble()) {
        if(number != 0) {
            System.out.println("Reciprocal is " + 1 / number);
        }
        else {
            System.out.println("Invalid input");
        }
    }
    else {
        System.out.println("Invalid Input");
    }