How to Find the Mean/Average of a List of Numbers in Java

The challenge

Find the mean (average) of a list of numbers in an array.

To find the mean (average) of a set of numbers add all of the numbers together and divide by the number of values in the list.

For an example list of 1, 3, 5, 7

1. Add all of the numbers

1+3+5+7 = 16

2. Divide by the number of values in the list. In this example there are 4 numbers in the list.

16/4 = 4

3. The mean (or average) of this list is 4

Test cases

import static org.junit.Assert.*; import org.junit.Test; public class AveragerTest { @Test public void test1() { assertEquals(1, Averager.findAverage(new int[]{1})); } @Test public void test2() { assertEquals(4, Averager.findAverage(new int[]{1,3,5,7})); } }
Code language: Java (java)

Find the Mean/Average in Java

Avoid performing a for loop, in favour of an Arrays.stream:

import java.util.*; public class Averager { public static int findAverage(int[] nums) { // sum all the elements and divide by the amount of elements return Arrays.stream(nums).sum()/nums.length; } }
Code language: Java (java)

Alternatively, use the average functional directly and avoid summing and dividing by the length:

import java.util.Arrays; public class Averager { public static int findAverage(int[] nums) { // or use the internal `average` return (int)Arrays.stream(nums).average().orElse(0); } }
Code language: Java (java)

Another great option is to use the summaryStatistics extension of the InStream class to then in turn use the getAverage method as follows:

import java.util.stream.IntStream; public class Averager { public static int findAverage(int[] nums) { // or explore the `summaryStatistics` route return (int)IntStream.of(nums).summaryStatistics().getAverage(); } }
Code language: Java (java)

If all else fails, there’s always good old faithful, using a for loop:

public class Averager { public static int findAverage(int[] nums) { int sum = 0; for (int num : nums) { sum += num; } return sum / nums.length; } }
Code language: Java (java)
Tags:
Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments