Question

Questions Write a method that returns the union of two array lists of integers using the following header: public static ArrayList<Integer> union(ArrayList<Integer> list1, ArrayList<Integer> list2)

Write a test program that: 1. prompts the user to enter two lists, each with five integers, 2. displays their union numbers separated by exactly one space., and 3. finds the maximum number and the minimum number in the combined list. Here is a sample run of the program.

Enter five integers for list1: 5 3 22 32 6 Enter five integers for list2: 9 7 33 4 17 The Combined list is 5 3 22 32 6 9 7 33 4 17 The Maximum is 33 The Minimum is 3

Answer 1

package com.test;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

public class ArrayListUnion {

   public static ArrayList<Integer> union(ArrayList<Integer> list1, ArrayList<Integer> list2) {
       ArrayList<Integer> unionList = new ArrayList<Integer>();
       //set to hold unique values
       Set<Integer> output = new HashSet<Integer>();

       for (int i = 0; i < list1.size(); i++) {
           output.add(list1.get(i));

           for (int j = 0; j < list2.size(); j++) {
               output.add(list2.get(j));
           }
       }
       //Add to output list
       for(int i : output) {
           unionList.add(i);
       }
       //return
       return unionList;
   }

   public static void main(String[] args) {
       // TODO Auto-generated method stub
       //Create two list
       ArrayList<Integer> list1 = new ArrayList<Integer>();
       ArrayList<Integer> list2 = new ArrayList<Integer>();
       //Add int
       list1.add(5);
       list1.add(3);
       list1.add(22);
       list1.add(32);
       list1.add(6);

       list2.add(9);
       list2.add(7);
       list2.add(33);
       list2.add(4);
       list2.add(17);
       //Call union
       ArrayList<Integer> unionList = union(list1, list2);
       //Display
       System.out.println("List 1: " + list1);
       System.out.println("List 2" + list2);
       System.out.println("The Combined list is: " + unionList);
       //Sort list to find minimum and maximum
       Collections.sort(unionList);
       //Display minimum and maximum
       System.out.println("Minimum: " + unionList.get(0));
       System.out.println("Maximum: " + unionList.get(unionList.size() - 1));
   }

}

------------

List 1: [5, 3, 22, 33, 6]
List 2[9, 7, 33, 4, 17]
The Combined list is: [33, 17, 3, 4, 5, 22, 6, 7, 9]
Minimum: 3
Maximum: 33