Please write the code in java
(Recursion):
Implement a SubsetGenerator that generates all subsets of the characters of a string. For example, the subsets of the characters of the string “rum” are the eight strings
“rum”, “ru”, “rm”, “r”, “um”, “u”, “m”, “ ”
Note that the subsets don’t have to be substrings – for example, “rm” isn’t a sub-string of “rum”.
(Sorting and Searching):
Write a program that selection sort algorithm to sort an array of integers in descending order.
(Sorting and Searching):
Sort an array list of strings by increasing length, Hint: Supply a Comparator.