I have an int filled out by the user on the console and I need to check if the input given was a non number. How to I do that?

Question

Java. In brackets you see what I want to do.

if (variableThatIsAnInt != [intType])
System.out.println("invalid option");

Answer 1

A variable which is an int or Integer can never be anything else than this type. This is only possible if you ditch the typing completely and define everything as an Object only.

As an example:

Integer myVar = 1;
Object myDirtyVar = myVar;

A check whether myVar is an instance of Integer would always be true.

What you are actually looking for is to check whether a String value is assignable to a numerical (in this case: Integer) number.

This can be done multiple ways, one way would be the following:

What's the best way to check if a String represents an integer in Java?

Another way is to try to parse/convert it and then catch the Exception (NumberFormatException) which may appear if the String is not representing an Integer.