Checking if userInput is number with exception

Question

Im trying to check whether the input from the User is an int or not.

Heres my code so far:

static int readInt(Scanner userInput) {
    int intValue = 0;

    try {
    System.out.print("Please enter a number:");
    intValue = Integer.parseInt(userInput.nextLine());


    } catch (NumberFormatException ex) {
    Input.readInt(userInput);

    }
    return intValue;
}

The problem is: if I first give it input which is not a number and then after that i give it a number it always returns 0. If i give it a number the first attempt it returns the number I have given it.

What am I missing? Thanks in advance

edit: Im only allowed to use Integer.parseInt and Exceptions.

You are not assigning the return value of Input.readInt(userInput); to your intValue — user6073886
– user6073886, Commented Nov 22, 2017 at 11:02
Consider wrapping the input code in while-loop to ensure that the program only continues forward when valid input has been received. — Henrik Aasted Sørensen
– Henrik Aasted Sørensen, Commented Nov 22, 2017 at 11:03
If you're only allowed to use Integer.parseInt and Exceptions, please edit your question and add this requirement. — Mickael
– Mickael, Commented Nov 22, 2017 at 11:09

DevJava · Accepted Answer · 2017-11-22 11:12:42Z

1

To avoid your problem, in the catch block you need to assign this Input.readInt(userInput) to your variable. like this :

intValue  = Input.readInt(userInput);

answered Nov 22, 2017 at 11:12

DevJava

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Comments

Vlant · Accepted Answer · 2017-11-22 11:04:45Z

0

It looks like you are not setting the variable in the catch

intValue = Input.readInt(userInput);

answered Nov 22, 2017 at 11:04

Vlant

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1 Comment

user7852469 Over a year ago

That solved it, thanks! so I dont have to put "Input.readInt(userInput);" in my catch then at all, right?

TEXHIK · Accepted Answer · 2017-11-22 11:26:51Z

0

Recursion is overhead here. use loop:

Integer result = null;
do {
    System.out.print("Please enter a number:");
    try {
        result = Integer.parseInt(userInput.nextLine());
    } catch (NumberFormatException ex) {
        System.out.print("Not a number");
    }
} while(result==null);
return result;

answered Nov 22, 2017 at 11:26

TEXHIK

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