BAEL-1586 Sum and Average in Java Array (#3718)

* Evaluation Article

* CR comments resolved

* BAEL-1586 Find Sum and Average in Java Array

* Revert "CR comments resolved"

This reverts commit c9bf88fcd58773d3df34e2a6cb4db44c3b54777d.

* Revert "Evaluation Article"

This reverts commit 41ad30313ab2c454350b5accdee531dba80e7ea9.

* BAEL-1586 Removed Author Description

* BAEL-1586 Find Sum And Avergae In Array

* remove excess whitespace

core-java/src/main/java/com/baeldung/array/Find2ndLargestInArray.java

@@ -0,0 +1,20 @@
+package com.baeldung.array;
+
+public class Find2ndLargestInArray {
+
+    public static int find2ndLargestElement(int[] array) {
+        int maxElement = array[0];
+        int secondLargestElement = -1;
+
+        for (int index = 0; index < array.length; index++) {
+            if (maxElement <= array[index]) {
+                secondLargestElement = maxElement;
+                maxElement = array[index];
+            } else if (secondLargestElement < array[index]) {
+                secondLargestElement = array[index];
+            }
+        }
+        return secondLargestElement;
+    }
+
+}

core-java/src/main/java/com/baeldung/array/FindElementInArray.java

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+package com.baeldung.array;
+
+import java.util.Arrays;
+
+public class FindElementInArray {
+
+    public static boolean findGivenElementInArrayWithoutUsingStream(int[] array, int element) {
+        boolean actualResult = false;
+
+        for (int index = 0; index < array.length; index++) {
+            if (element == array[index]) {
+                actualResult = true;
+                break;
+            }
+        }
+        return actualResult;
+    }
+
+    public static boolean findGivenElementInArrayUsingStream(int[] array, int element) {
+        return Arrays.stream(array).filter(x -> element == x).findFirst().isPresent();
+    }
+}

core-java/src/main/java/com/baeldung/array/SumAndAverageInArray.java

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+package com.baeldung.array;
+
+import java.util.Arrays;
+
+public class SumAndAverageInArray {
+
+    public static int findSumWithoutUsingStream(int[] array) {
+        int sum = 0;
+        for (int index = 0; index < array.length; index++) {
+            sum += array[index];
+        }
+        return sum;
+    }
+
+    public static int findSumUsingStream(int[] array) {
+        return Arrays.stream(array).sum();
+    }
+
+    public static double findAverageWithoutUsingStream(int[] array) {
+        int sum = findSumWithoutUsingStream(array);
+        return (double) sum / array.length;
+    }
+
+    public static double findAverageUsingStream(int[] array) {
+        return Arrays.stream(array).average().getAsDouble();
+    }
+}

core-java/src/test/java/com/baeldung/array/Find2ndLargestInArrayTest.java

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+package com.baeldung.array;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class Find2ndLargestInArrayTest {
+    @Test
+    public void givenAnIntArray_thenFind2ndLargestElement() {
+        int[] array = { 1, 3, 24, 16, 87, 20 };
+        int expected2ndLargest = 24;
+
+        int actualSecondLargestElement = Find2ndLargestInArray.find2ndLargestElement(array);
+
+        Assert.assertEquals(expected2ndLargest, actualSecondLargestElement);
+    }
+}

core-java/src/test/java/com/baeldung/array/FindElementInArrayTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.array;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FindElementInArrayTest {
+    @Test
+    public void givenAnIntArray_whenNotUsingStream_thenFindAnElement() {
+        int[] array = { 1, 3, 4, 8, 19, 20 };
+        int element = 19;
+        boolean expectedResult = true;
+        boolean actualResult = FindElementInArray.findGivenElementInArrayWithoutUsingStream(array, element);
+        Assert.assertEquals(expectedResult, actualResult);
+
+        element = 78;
+        expectedResult = false;
+        actualResult = FindElementInArray.findGivenElementInArrayWithoutUsingStream(array, element);
+        Assert.assertEquals(expectedResult, actualResult);
+    }
+
+    @Test
+    public void givenAnIntArray_whenUsingStream_thenFindAnElement() {
+        int[] array = { 15, 16, 12, 18 };
+        int element = 16;
+        boolean expectedResult = true;
+        boolean actualResult = FindElementInArray.findGivenElementInArrayUsingStream(array, element);
+        Assert.assertEquals(expectedResult, actualResult);
+
+        element = 20;
+        expectedResult = false;
+        actualResult = FindElementInArray.findGivenElementInArrayUsingStream(array, element);
+        Assert.assertEquals(expectedResult, actualResult);
+    }
+
+}

core-java/src/test/java/com/baeldung/array/SumAndAverageInArrayTest.java

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+package com.baeldung.array;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class SumAndAverageInArrayTest {
+    @Test
+    public void givenAnIntArray_whenNotUsingStream_thenFindSum() {
+        int[] array = { 1, 3, 4, 8, 19, 20 };
+        int expectedSumOfArray = 55;
+        int actualSumOfArray = SumAndAverageInArray.findSumWithoutUsingStream(array);
+        Assert.assertEquals(expectedSumOfArray, actualSumOfArray);
+    }
+
+    @Test
+    public void givenAnIntArray_whenUsingStream_thenFindSum() {
+        int[] array = { 1, 3, 4, 8, 19, 20 };
+        int expectedSumOfArray = 55;
+        int actualSumOfArray = SumAndAverageInArray.findSumUsingStream(array);
+
+        Assert.assertEquals(expectedSumOfArray, actualSumOfArray);
+    }
+
+    @Test
+    public void givenAnIntArray_whenNotUsingStream_thenFindAverage() {
+        int[] array = { 1, 3, 4, 8, 19, 20 };
+        double expectedAvgOfArray = 9.17;
+        double actualAvgOfArray = SumAndAverageInArray.findAverageWithoutUsingStream(array);
+
+        Assert.assertEquals(expectedAvgOfArray, actualAvgOfArray, 0.0034);
+    }
+
+    @Test
+    public void givenAnIntArray_whenUsingStream_thenFindAverage() {
+        int[] array = { 1, 3, 4, 8, 19, 20 };
+        double expectedAvgOfArray = 9.17;
+        double actualAvgOfArray = SumAndAverageInArray.findAverageUsingStream(array);
+
+        Assert.assertEquals(expectedAvgOfArray, actualAvgOfArray, 0.0034);
+    }
+}