Write a Java program that can calculate and print out the area of a square. The user enters data of the side and its measurement unit (in for inch, ft for feet, cm for centimeter, and m for meter) from the console. The program should check to be sure that the side is not negative and the measurement unit must be one among the listed-above units.

Important Notes:

Assumed that the user makes mistakes at most once for the side value and once for the measurement unit while entering the data, i.e. he/she enters the correct value the next time right after being warned.