Java Program to Find Average of Two Lists

// Java Program using the
// somple for loops len(), and + operators
import java.util.*; //imports all the util packages

// Driver Class
public class Main {
    // main function
    public static void main(String[] args)
    {
        // Creating two lists
        List<Integer> list1 = new ArrayList<Integer>();
        List<Integer> list2 = new ArrayList<Integer>();
        // Adding elements in the two lists
        list1.add(1);
        list1.add(2);
        list1.add(3);
        list2.add(4);
        list2.add(5);
        list2.add(6);

        double avg = 0;
        // Using for loops to find the average
        for (int i = 0; i < list1.size(); i++)
            avg += list1.get(i);
        for (int i = 0; i < list2.size(); i++)
            avg += list2.get(i);

        int l = list1.size() + list2.size();

        System.out.println("Average: " + avg / l);
    }
}

// Java Program to Using the 
// sum(), len(), and + operators
import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

// Driver Class
public 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);
    }
}

// Java Program to demonstrate
// Using sum() + len() + chain()
import java.io.*;
import java.util.*;
import java.util.stream.*;

// Driver Class
public 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);
    }
}