The challenge

Write function avg which calculates average of numbers in given list.

The solution in Java code

Option 1 (working through the problem):

 public class Solution { public static double find_average(int[] array){ double sum = 0; for(int i=0; i

Option 2 (using streams):

 import java.util.Arrays; public class Solution { public static double find_average(int[] array){ return Arrays.stream(array).average().orElse(0); } }

Option 3 (using an IntStream):

 import java.util.stream.IntStream; public class Solution { public static double find_average(int[] array){ return IntStream.of(array).average().getAsDouble(); } }

Option 4 (an alternate IntStream approach):

 import java.util.stream.IntStream; public class Solution { public static double find_average(int[] array){ return IntStream.of(array).sum() / (double) array.length; } }

Test cases to validate our solution

 import org.junit.Test; import static org.junit.Assert.assertEquals; import org.junit.runners.JUnit4; public class SolutionTest { private static final double DELTA = 1e-15; @Test public void testSomething() { assertEquals(1, Solution.find_average(new int[]{1,1,1}), DELTA); assertEquals(2, Solution.find_average(new int[]{1, 2, 3}), DELTA); assertEquals(2.5, Solution.find_average(new int[]{1, 2, 3, 4}), DELTA); System.out.println("Running 20 random tests..."); for(int i=0; i<20; i++){ int[] arr = randArray(); assertEquals(solution(arr), Solution.find_average(arr), DELTA); } } private static int[] randArray(){ int size = (int)Math.floor(Math.random()*5 + 2); int[] arr = new int[size]; for(int i=0; i