few java programs I need help with

Write a JAVA program to check if a number entered by the user is Odd or Even. If the number is Odd, also check whether it is Prime or not.

Write a JAVA program using method() to find the compound interest on a principle entered by the user for a period of 5 years compounded annually at 2% rate of interest.

What is the difference between run-time and compile-time error ?

THANKS !!!