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})); } }
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; } }
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); } }
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(); } }
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; } }