Fatal Exception: java.lang.NullPointerException Attempt to invoke virtual method 'int java.lang.String.length ()' on a null object reference #43 ...

This method will return Student object if rollNo matches with any of the Student object or else it will throw an user defined exception InvalidStudentException.

This tutorial on how to use the Java Scanner for user input will quickly show you how to import java.util, take String, int, double and char input, and teach you the difference between the ...