For java program have some little program

Exercise 2: Write a recursive method called countDown(int n) that takes a single int parameter, n>-0, and displays a countdown. For example, countDown (10) would display 10 BlastOff! Write a main method that prompts the user to enter a positive integer n and counts down to 1 from n Exercise 3: Modify the above method so that if n is even, it displays only even numbers in the countdown, whereas if n is odd, it displays only odd numbers in the countdown For example, countDown(10) would print 4 BlastOff! and countdown(9) would print BlastOff! Exercise 4: Write a recursive method to display the first m multiples of a positive integer n. For example, if n is 2 and m is 5, it should display 2, 4, 6, 8, 10. As a second example, if n is 3 and m is 6, then it should display 3, 6,9, 12, 15, 18 (Order doesn't matter) Write a main method that prompts the user to enter a positive integer n and displays as above