title: How to check if a string is numeric?
body: <p>I have a gpa program, and it works with the <code>equalsIgnoreCase()</code> method which compares two strings, the letter "a" to the user input, which checks if they put "a" or not. But now I want to add an exception with an error message that executes when a number is the input. I want the program to realize that the integer input is not the same as string and give an error message. Which methods can I use to compare a type <em>String</em> variable to input of type <em>int</em>, and throw exception?</p>