Throwing exceptions for wrong data types?

[Kar Man]

Hi, in the case that I want to throw an exception when the wrong type of data type is entered, how can I do this with IllegalArgumentException?

 
int row = console.nextInt();
		if(row < 1) {
			row = 1;
		}
		if(row > 5) {
			row = 5;
		}
		if (row != int) {
			throw new IllegalArgumentException("Please enter appropriate integer.");
		}

For instance, if someone were to enter a double, string, or boolean input into the scanner instead of an integer, how could I throw an exception for this? I have to do this for an assignment, and they specifically said that I need to use a throw exception for this. Thanks everyone in advance!

[Henry Wong]

Sameer Kan wrote:For instance, if someone were to enter a double, string, or boolean input into the scanner instead of an integer, how could I throw an exception for this? I have to do this for an assignment, and they specifically said that I need to use a throw exception for this. Thanks everyone in advance!

The Scanner class nextInt() method will throw an InputMismatchException exception, if the token is not an integer. So, you can catch the InputMismatchException instance and throw an IllegalArgumentException upon catching in the catch block.

Now, having said that, if this is a homework assignment, then I don't think your instructor wants you to use the nextInt() method. Instead, your instructor is probably expecting you to use the next() method instead. This method returns a raw token (string), which you can parse out the integer (or throw the exception).

Henry

[Carey Brown]

Henry has mentioned a way to deal with the problem. I'm not sure I agree with Henry though. Seems like you could use hasNextInt() to do what you want.

[Campbell Ritchie]

There are ways to ensure that an error message is passed if the wrong data type is entered, allowing you to enter new data, and avoid all exceptions. I think Carey is right, but in case of doubt, ask your teacher for clarification.