Combine two lists (Using ArrayList java)

Write a method that returns the union of two array lists of integers using the following header: public static ArrayList union( ArrayList list1, ArrayList list2) For example, the union of two array lists {2,3,1,5} and {3,4,6} is {2, 3, 1, 5, 3, 4, 6}. 1. Write a test program that prompts the user to enter two lists, each with five integers, and displays their union. The numbers are separated by exactly one space in the output.

2. What shall you do if you need to merge and sort the array?