To calculate the average of two lists in Java we first need to combine the two lists into one. we can do this using the addAll() method of the ArrayList class. Once you have combined the lists we can calculate the average by summing up all the elements in the combined list and dividing by the total number of factors.
Methods to Find Average of Two Lists
There are two methods to find the average of the two lists are mentioned below:
- Using the sum(), len() and + Operators
- Using sum() + len() + chain()
1. Using the sum(), len(), and + operators
Below is the Implementation of the above method:
Java
// Java Program to Using the // sum(), len(), and + operatorsimport java.io.*;import java.util.ArrayList;import java.util.Arrays;import java.util.List; // Driver Classpublic class Main { // main function public static void main(String[] args) { List<Integer> list1 = new ArrayList<>(Arrays.asList(1, 2, 3)); List<Integer> list2 = new ArrayList<>(Arrays.asList(4, 5, 6)); double average = ((double)list1.stream() .mapToInt(Integer::intValue).sum() + (double)list2.stream() .mapToInt(Integer::intValue).sum()) / (list1.size() + list2.size()); System.out.println("Average: " + average); }} |
Output
Average: 3.5
2. Using sum() + len() + chain()
Below is the Implementation of the above method:
Java
// Java Program to demonstrate// Using sum() + len() + chain()import java.io.*;import java.util.*;import java.util.stream.*; // Driver Classpublic class AverageOfTwoLists { // main function public static void main(String[] args) { List<Integer> list1 = Arrays.asList(1, 2, 3, 4, 5); List<Integer> list2 = Arrays.asList(6, 7, 8, 9, 10); double average = Stream.concat(list1.stream(), list2.stream()) .mapToInt(Integer::intValue) .average() .orElse(Double.NaN); System.out.println("Average: " + average); }} |
Output
Average: 5.5
