Question

Write a method that returns the union of two arrays lists of integers using the following header:

Public static ArrayList union(Array list, ArrayList list2)
For example, the addition of two array lists (2,3,1,5) and (3,4,6) is (2,3,1,5,3,4,6).
Write a test program that prompts the user to enter two lists, each with five integers, and displays their union. The number are separated by exactly one space. Here is a sample run:

Enter five integers for list1: 3 5 45 4 3
Enter five integers for list2: 33 51 5 4 13
The combined list is 3 5 45 4 3 33 51 5 4 13

Answer 1

import java.util.*;

public class Main

{

public static void main(String[] args) {

Scanner input = new Scanner(System.in);

ArrayList<Integer> l1 = new ArrayList<Integer>(5);

ArrayList<Integer> l2 = new ArrayList<Integer>(5);

System.out.println("Enter five integers for list1: ");

for (int i=0; i<5; i++) {

int x = input.nextInt();

l1.add(x);

}

System.out.println("Enter five integers for list2: ");

for (int i=0; i<5; i++) {

int x = input.nextInt();

l2.add(x);

}

System.out.println(union(l1, l2));

}

public static ArrayList<Integer> union(ArrayList<Integer> list, ArrayList<Integer> list2) {

for (int i:list2)

list.add(i);

return list;

}

}

Step-by-step explanation:

Create a method called union takes two lists, list and list2

Inside the method:

Initialize a for loop iterates through the list2

Add all the elements in list2 to list

Return the list

Inside the main:

Declare the lists

Ask the user for the numbers and put them in the lists

Call the union method to combine the lists and print the combined list