Receiving float from Scanner input Java

Question

I need a method that should check whether user's input is a float, and if it is string or int it should throw an exception.

I declare the Scanner outside of the method:

    Scanner sc = new Scanner(System.in);

And the method definition is:

private boolean CheckFloat(Scanner sc) throws MyException {
    if(!sc.hasNextFloat()){
        throw new MyException("Wrong type");
    }
    else {
        float input = sc.nextFloat();
        if(input%1==0) {
            throw new MyException("Wrong type");
        }
        else return true;
    }
}

The problem is that the exception is thrown no matter what the user types in, so my question is: what exactly do I do wrong?

I know that in Java an input like 1.2 is interpreted as double, but how to take a float from the console then? Or do I misunderstand working of the method hasNextFloat() or the whole Scanner?

I haven't found anything helpful so far

Solution

Since you're using nextFloat() you must be sure that you enter a floating number, otherwise clear the scanner with next()

public static void main(String[] args) throws Exception {
    while (true) {
        System.out.print("Enter a float: ");
        try {
            float myFloat = input.nextFloat();
            if (myFloat % 1 == 0) {
                throw new Exception("Wrong type");
            }
            System.out.println(myFloat);
        } catch (InputMismatchException ime) {
            System.out.println(ime.toString());
            input.next(); // Flush the buffer from all data
        }
    }
}

Results:

UPDATE

You still have to handle the InputMismatchException, just throw your own exception in the catch block.

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);

    // while (true) just for testing
    while (true) {
        try {
            System.out.print("Enter a float: ");
            System.out.println(CheckFloat(input));
        } catch (MyException me) {
            System.out.println(me.toString());
        }
    }
}

private static float CheckFloat(Scanner sc) throws MyException {
    try {
        float input = sc.nextFloat();
        if (input % 1 == 0) {
            throw new MyException("Wrong type");
        } else {
            return input;
        }
    } catch (InputMismatchException ime) {
        sc.next(); // Flush the scanner

        // Rethrow your own exception
        throw new MyException("Wrong type");
    }
}

private static class MyException extends Exception {
    // You exception details
    public MyException(String message) {
        super(message);
    }
}

Results:

Comments

[JeramyRR]

You may need to make a call to sc.next() before your !sc.hasNextFloat()

[Kala]

Ok sorry I'm tired :p But for me it still throws exception also when I give the proper float input

[Kala]

As I corrected my code I noticed that it also accepted only the comma notation, and that's why your solution didn't work for me properly... So I guess I should just change the locale now. Sorry and thanks a lot for help anyway