The program should start with displaying a list of programs for all given problems. All the problems should be listed associated with a number e.g. Programs Available: 1. Factorial 2. Fibonacci Series 3. Contains ... 4. ... and so on Then the user should be asked to enter a choice to run the program. After the choice is made by entering the number, 1,2,.. etc., the corresponding program should run. First the program should take input of any variables required and then do the computation and show the result on the screen. Once the program is complete, the program should ask the user, whether program should continue or exit. If user selects continue, then the main list of programs should appear as it was displayed in the first instance. 1. Write a Java class called Factorial. This class defines a method called factorial () which takes as its only parameter an int called n, and returns an int representing the factorial of n. The factorial of an integer n, denoted n !, is defined as n(n1)(n2)1 (but note that 0 ! is 1). You MAY assume that n is a non-negative integer. 2. Write a Java class called Fibonacci. This class defines a method called fibonacci() which takes as its only parameter an int called n, and returns an int representing the nth Fibonacci number. The nth Fibonacci number, denoted fn, is defined as follows: f0=0fl=1fn=fn1+fn2 You MAY assume that n is a non-negative integer. Write a Java class called Contains. This class defines a method called contains(), which takes as parameters an array of int called a as well as an int called x, and returns a boolean which is true if and only if x occurs in a, false otherwise. Write a Java class called Maximum. This class defines a method called maximum(), which takes as its only parameter an array of int called a, and returns an int representing the maximum value which occurs in the array. 5. Write a Java class called CountOccurrences. This class defines a method called countOccurrences(), which takes as parameters an array of int called a as well as a int called x, and returns an int representing the number of elements of a which are equal to x. 6. Write a Java class called Reverse. This class defines a method called reverse(), which takes as its only parameter an array of int called a, and returns a new array of int which contains all the elements in a, but in the reverse order