Bael 8351 (#17280)

* BAEL-7765: How to fix JsonParseException: Unexpected character (code 115) when parsing unquoted JSON in Jackson

* BAEL-8243: the @ApplicationModuleListener annotation already includes the functionality of @async

* BAEL-8351
How to Calculate Average of an 2d Array in Java

* BAEL-8351: How to Calculate Average of an 2d Array in Java

Author: achraftt

core-java-modules/core-java-arrays-operations-advanced/src/main/java/com/baeldung/array/AverageIn2DArray.java

@@ -0,0 +1,24 @@
+package com.baeldung.array;
+
+import java.util.Arrays;
+import java.util.OptionalDouble;
+
+public class AverageIn2DArray {
+    public static double findAverageWithoutUsingStream(int[][] array) {
+        int sum = 0;
+        int count = 0;
+        for (int[] row : array) {
+            for (int value : row) {
+                sum += value;
+                count++;
+            }
+        }
+        return (double) sum / count;
+    }
+
+    public static OptionalDouble findAverageUsingStream(int[][] array) {
+        return Arrays.stream(array)
+                .flatMapToInt(Arrays::stream)
+                .average();
+    }
+}

core-java-modules/core-java-arrays-operations-advanced/src/test/java/com/baeldung/array/AverageIn2DArrayUnitTest.java

@@ -0,0 +1,138 @@
+package com.baeldung.array;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.OptionalDouble;
+
+public class AverageIn2DArrayUnitTest {
+
+    private static final int[][] singleElementArray = {{5}};
+    private static final int[][] positiveNumbersArray = {
+            {1, 2, 3},
+            {4, 5, 6},
+            {7, 8, 9}
+    };
+    private static final int[][] mixedNumbersArray = {
+            {-3, 4, -2},
+            {1, -5, 6},
+            {2, 0, -1}
+    };
+    private static final int[][] zerosArray = {
+            {0, 0, 0},
+            {0, 0, 0},
+            {0, 0, 0}
+    };
+    private static final int[][] emptyArray = {};
+    private static final int[][] emptyRowsArray = {{}};
+    private static final int[][] irregularArray = {
+            {1, 2, 3},
+            {4, 5},
+            {6}
+    };
+
+
+    // Without Stream
+    @Test
+    public void givenSingleElementArray_whenNotUsingStream_thenFindAverage() {
+        double expectedAverage = 5.0;
+        double actualAverage = AverageIn2DArray.findAverageWithoutUsingStream(singleElementArray);
+        Assert.assertEquals(expectedAverage, actualAverage, 0.0001);
+    }
+
+    @Test
+    public void givenPositiveNumbersArray_whenNotUsingStream_thenFindAverage() {
+        double expectedAverage = 5.0;
+        double actualAverage = AverageIn2DArray.findAverageWithoutUsingStream(positiveNumbersArray);
+        Assert.assertEquals(expectedAverage, actualAverage, 0.0001);
+    }
+
+    @Test
+    public void givenMixedNumbersArray_whenNotUsingStream_thenFindAverage() {
+        double expectedAverage = 0.222;
+        double actualAverage = AverageIn2DArray.findAverageWithoutUsingStream(mixedNumbersArray);
+        Assert.assertEquals(expectedAverage, actualAverage, 0.001);
+    }
+
+    @Test
+    public void givenZerosArray_whenNotUsingStream_thenFindAverage() {
+        double expectedAverage = 0.0;
+        double actualAverage = AverageIn2DArray.findAverageWithoutUsingStream(zerosArray);
+        Assert.assertEquals(expectedAverage, actualAverage, 0.0001);
+    }
+
+    @Test
+    public void givenEmptyArray_whenNotUsingStream_thenFindAverage() {
+        double expectedAverage = Double.NaN;
+        double actualAverage = AverageIn2DArray.findAverageWithoutUsingStream(emptyArray);
+        Assert.assertEquals(expectedAverage, actualAverage, 0.0001);
+    }
+
+    @Test
+    public void givenEmptyRowsArray_whenNotUsingStream_thenFindAverage() {
+        double expectedAverage = Double.NaN;
+        double actualAverage = AverageIn2DArray.findAverageWithoutUsingStream(emptyRowsArray);
+        Assert.assertEquals(expectedAverage, actualAverage, 0.0001);
+    }
+
+    @Test
+    public void givenIrregularArray_whenNotUsingStream_thenFindAverage() {
+        double expectedAverage = 3.5;
+        double actualAverage = AverageIn2DArray.findAverageWithoutUsingStream(irregularArray);
+        Assert.assertEquals(expectedAverage, actualAverage, 0.0001);
+    }
+
+    // Using Stream
+
+    @Test
+    public void givenSingleElementArray_whenUsingStream_thenFindAverage() {
+        double expectedAverage = 5.0;
+        OptionalDouble actualAverage = AverageIn2DArray.findAverageUsingStream(singleElementArray);
+        Assert.assertTrue("Expected average should be present", actualAverage.isPresent());
+        Assert.assertEquals(expectedAverage, actualAverage.getAsDouble(), 0.0001);
+    }
+
+    @Test
+    public void givenPositiveNumbersArray_whenUsingStream_thenFindAverage() {
+        double expectedAverage = 5.0;
+        OptionalDouble actualAverage = AverageIn2DArray.findAverageUsingStream(positiveNumbersArray);
+        Assert.assertTrue("Expected average should be present", actualAverage.isPresent());
+        Assert.assertEquals(expectedAverage, actualAverage.getAsDouble(), 0.0001);
+    }
+
+    @Test
+    public void givenMixedNumbersArray_whenUsingStream_thenFindAverage() {
+        double expectedAverage = 0.222;
+        OptionalDouble actualAverage = AverageIn2DArray.findAverageUsingStream(mixedNumbersArray);
+        Assert.assertTrue("Expected average should be present", actualAverage.isPresent());
+        Assert.assertEquals(expectedAverage, actualAverage.getAsDouble(), 0.001);
+    }
+
+    @Test
+    public void givenZerosArray_whenUsingStream_thenFindAverage() {
+        double expectedAverage = 0.0;
+        OptionalDouble actualAverage = AverageIn2DArray.findAverageUsingStream(zerosArray);
+        Assert.assertTrue("Expected average should be present", actualAverage.isPresent());
+        Assert.assertEquals(expectedAverage, actualAverage.getAsDouble(), 0.0001);
+    }
+
+    @Test
+    public void givenEmptyArray_whenUsingStream_thenFindAverage() {
+        OptionalDouble actualAverage = AverageIn2DArray.findAverageUsingStream(emptyArray);
+        Assert.assertFalse("Expected no average to be present", actualAverage.isPresent());
+    }
+
+    @Test
+    public void givenEmptyRowsArray_whenUsingStream_thenFindAverage() {
+        OptionalDouble actualAverage = AverageIn2DArray.findAverageUsingStream(emptyRowsArray);
+        Assert.assertFalse("Expected no average to be present", actualAverage.isPresent());
+    }
+
+    @Test
+    public void givenIrregularArray_whenUsingStream_thenFindAverage() {
+        double expectedAverage = 3.5;
+        OptionalDouble actualAverage = AverageIn2DArray.findAverageUsingStream(irregularArray);
+        Assert.assertTrue("Expected average should be present", actualAverage.isPresent());
+        Assert.assertEquals(expectedAverage, actualAverage.getAsDouble(), 0.0001);
+    }
+}