using java please?

3.45 (Factorial) The factorial of a nonnegative integer n is written n! (pronounced"n factorial") and is defined as follows and For example, 5!-5.4-3-2.1, which is 120. n!n (n-1) (n-2). .. (for values of n greater than or equal to 1) n!(for n 0). a) Write a program that reads a nonnegative integer and computes and prints its factorial. b) Write a program that estimates the value of the mathematical constant e by using the formula: 1 2 3! c) Write a program that computes the value of by using the formula 1! 2 3