Write a recursive method called 'vowels', that returns the number of vowels in a string

1. Write a recursive method expFive(n) to compute y=5^n. For instance, if n is 0, y is 1. If n is 3, then y is 125. If n is 4, then y is 625. The recursive method cannot have loops. Then write a testing program to call the recursive method. If you run your program, the results should look like this: > run RecExpTest Enter a number: 3 125 >run RecExpTest Enter a number: 3125 2. For two integers m and n, their GCD(Greatest Common Divisor) can be computed by a recursive function. Write a recursive method gcd(m,n) to find their Greatest Common Divisor. Once m is 0, the function returns n. Once n is 0, the function returns m. If neither is 0, the function can recursively calculate the Greatest Common Divisor with two smaller parameters: One is n, the second one is m mod n. Although there are other approaches to calculate Greatest Common Divisor, please follow the instructions in this question, otherwise you will not get the credit. Meaning your code needs to follow the given algorithm. Then…

Recursive Power MethodWrite a method called powCal that uses recursion to raise a number to a power. The method should accept two arguments: The first argument is the exponent and the second argument is the number to be raised (example” powCal(10,2) means 210). Assume that the exponent is a nonnegative integer. Demonstrate the method in a program called Recursive (This means that you need to write a program that has at least two methods: main and powCal. The powCal method is where you implement the requirements above and the main method is where you make a method call to demonstrate how your powCal method work).

Given a long string use recursion to traverse the string and replace every vowel (A,E,I,O,U) with an @ sign. You cannot change the method header. public String encodeVowels(String s){ // Your code here }