Merge branch 'master' of https://github.com/eugenp/tutorials into task/BAEL-20665

# Conflicts:
#	core-groovy-2/src/test/groovy/com/baeldung/metaprogramming/MetaprogrammingUnitTest.groovy
#	core-java-modules/pom.xml
#	pom.xml

algorithms-miscellaneous-3/README.md

@@ -15,5 +15,4 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Creating a Triangle with for Loops in Java](https://www.baeldung.com/java-print-triangle)
 - [Efficient Word Frequency Calculator in Java](https://www.baeldung.com/java-word-frequency)
 - [The K-Means Clustering Algorithm in Java](https://www.baeldung.com/java-k-means-clustering-algorithm)
-- [Creating a Custom Annotation in Java](https://www.baeldung.com/java-custom-annotation)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-2) [[next -->]](/algorithms-miscellaneous-4)

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/greedy/GreedyAlgorithm.java

@@ -15,7 +15,7 @@ public class GreedyAlgorithm {
         this.fp = new FollowersPath();
     }
     
-    public long findMostFollowersPath(String account) throws Exception {        
+    public long findMostFollowersPath(String account) {
         long max = 0;
         SocialUser toFollow = null;
         
@@ -31,12 +31,8 @@ public class GreedyAlgorithm {
         if (currentLevel < maxLevel - 1) {
             currentLevel++;
             max += findMostFollowersPath(toFollow.getUsername());
-            //fp.addFollower(toFollow.getUsername(), max);
-            //fp.addCount(max);
             return max;
         } else {
-            //fp.addFollower(toFollow.getUsername(), max);
-            //fp.addCount(max);
             return max;
         }            
     }

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/greedy/NonGreedyAlgorithm.java

@@ -13,9 +13,8 @@ public class NonGreedyAlgorithm {
         this.tc = tc;
         this.currentLevel = level;
     }
-    
-    
-    public long findMostFollowersPath(String account) throws Exception {        
+      
+    public long findMostFollowersPath(String account) {
         List<SocialUser> followers = tc.getFollowers(account);
         long total = currentLevel > 0 ? followers.size() : 0;
 

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/greedy/SocialConnector.java

@@ -20,9 +20,9 @@ public class SocialConnector {
         return this.isCounterEnabled;
     }
     
-    public List<SocialUser> getFollowers(String account) throws Exception {
+    public List<SocialUser> getFollowers(String account) {
         if (counter < 0)
-            throw new Exception ("API limit reached");
+            throw new IllegalStateException ("API limit reached");
         else {
             if(this.isCounterEnabled) counter--;
             for(SocialUser user : users) {

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/minheapmerge/HeapNode.java

@@ -0,0 +1,13 @@
+package com.baeldung.algorithms.minheapmerge;
+
+public class HeapNode {
+
+    int element;
+    int arrayIndex;
+    int nextElementIndex = 1;
+
+    public HeapNode(int element, int arrayIndex) {
+        this.element = element;
+        this.arrayIndex = arrayIndex;
+    }
+}

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/minheapmerge/MinHeap.java

@@ -0,0 +1,88 @@
+package com.baeldung.algorithms.minheapmerge;
+
+public class MinHeap {
+
+    HeapNode[] heapNodes;
+
+    public MinHeap(HeapNode heapNodes[]) {
+        this.heapNodes = heapNodes;
+        heapifyFromLastLeafsParent();
+    }
+
+    void heapifyFromLastLeafsParent() {
+        int lastLeafsParentIndex = getParentNodeIndex(heapNodes.length);
+        while (lastLeafsParentIndex >= 0) {
+            heapify(lastLeafsParentIndex);
+            lastLeafsParentIndex--;
+        }
+    }
+
+    void heapify(int index) {
+        int leftNodeIndex = getLeftNodeIndex(index);
+        int rightNodeIndex = getRightNodeIndex(index);
+        int smallestElementIndex = index;
+        if (leftNodeIndex < heapNodes.length && heapNodes[leftNodeIndex].element < heapNodes[index].element) {
+            smallestElementIndex = leftNodeIndex;
+        }
+        if (rightNodeIndex < heapNodes.length && heapNodes[rightNodeIndex].element < heapNodes[smallestElementIndex].element) {
+            smallestElementIndex = rightNodeIndex;
+        }
+        if (smallestElementIndex != index) {
+            swap(index, smallestElementIndex);
+            heapify(smallestElementIndex);
+        }
+    }
+
+    int getParentNodeIndex(int index) {
+        return (index - 1) / 2;
+    }
+
+    int getLeftNodeIndex(int index) {
+        return (2 * index + 1);
+    }
+
+    int getRightNodeIndex(int index) {
+        return (2 * index + 2);
+    }
+
+    HeapNode getRootNode() {
+        return heapNodes[0];
+    }
+
+    void heapifyFromRoot() {
+        heapify(0);
+    }
+
+    void swap(int i, int j) {
+        HeapNode temp = heapNodes[i];
+        heapNodes[i] = heapNodes[j];
+        heapNodes[j] = temp;
+    }
+    
+    static int[] merge(int[][] array) {
+        HeapNode[] heapNodes = new HeapNode[array.length];
+        int resultingArraySize = 0;
+
+        for (int i = 0; i < array.length; i++) {
+            HeapNode node = new HeapNode(array[i][0], i);
+            heapNodes[i] = node;
+            resultingArraySize += array[i].length;
+        }
+        
+        MinHeap minHeap = new MinHeap(heapNodes);
+        int[] resultingArray = new int[resultingArraySize];
+
+        for (int i = 0; i < resultingArraySize; i++) {
+            HeapNode root = minHeap.getRootNode();
+            resultingArray[i] = root.element;
+
+            if (root.nextElementIndex < array[root.arrayIndex].length) {
+                root.element = array[root.arrayIndex][root.nextElementIndex++];
+            } else {
+                root.element = Integer.MAX_VALUE;
+            }
+            minHeap.heapifyFromRoot();
+        }
+        return resultingArray;
+    }
+}

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/greedy/GreedyAlgorithmUnitTest.java

@@ -35,21 +35,21 @@ public class GreedyAlgorithmUnitTest {
     }
 
     @Test
-    public void greedyAlgorithmTest() throws Exception {
+    public void greedyAlgorithmTest() {
         GreedyAlgorithm ga = new GreedyAlgorithm(prepareNetwork());
         assertEquals(ga.findMostFollowersPath("root"), 5);
     }
 
     @Test
-    public void nongreedyAlgorithmTest() throws Exception {
+    public void nongreedyAlgorithmTest() {
         NonGreedyAlgorithm nga = new NonGreedyAlgorithm(prepareNetwork(), 0);
-        Assertions.assertThrows(Exception.class, () -> {
+        Assertions.assertThrows(IllegalStateException.class, () -> {
             nga.findMostFollowersPath("root");
           });
     }
 
     @Test
-    public void nongreedyAlgorithmUnboundedTest() throws Exception {
+    public void nongreedyAlgorithmUnboundedTest() {
         SocialConnector sc = prepareNetwork();
         sc.switchCounter();
         NonGreedyAlgorithm nga = new NonGreedyAlgorithm(sc, 0);

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/minheapmerge/MinHeapUnitTest.java

@@ -0,0 +1,22 @@
+package com.baeldung.algorithms.minheapmerge;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+import org.junit.Test;
+
+public class MinHeapUnitTest {
+
+    private final int[][] inputArray = { { 0, 6 }, { 1, 5, 10, 100 }, { 2, 4, 200, 650 } };
+    private final int[] expectedArray = { 0, 1, 2, 4, 5, 6, 10, 100, 200, 650 };
+
+    @Test
+    public void givenSortedArrays_whenMerged_thenShouldReturnASingleSortedarray() {
+        int[] resultArray = MinHeap.merge(inputArray);
+        
+        assertThat(resultArray.length, is(equalTo(10)));
+        assertThat(resultArray, is(equalTo(expectedArray)));
+    }
+    
+}

algorithms-searching/README.md

@@ -9,3 +9,4 @@ This module contains articles about searching algorithms.
 - [Breadth-First Search Algorithm in Java](https://www.baeldung.com/java-breadth-first-search)
 - [String Search Algorithms for Large Texts](https://www.baeldung.com/java-full-text-search-algorithms)
 - [Monte Carlo Tree Search for Tic-Tac-Toe Game](https://www.baeldung.com/java-monte-carlo-tree-search)
+- [Range Search Algorithm in Java](https://www.baeldung.com/java-range-search)

algorithms-sorting-2/.gitignore

@@ -0,0 +1,4 @@
+/target/
+.settings/
+.classpath
+.project

algorithms-sorting-2/pom.xml

@@ -0,0 +1,64 @@
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>algorithms-sorting-2</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>algorithms-sorting-2</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-math3</artifactId>
+            <version>${commons-math3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-codec</groupId>
+            <artifactId>commons-codec</artifactId>
+            <version>${commons-codec.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit-jupiter-api.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${org.assertj.core.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.codehaus.mojo</groupId>
+                    <artifactId>exec-maven-plugin</artifactId>
+                    <version>${exec-maven-plugin.version}</version>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
+
+    <properties>
+        <commons-math3.version>3.6.1</commons-math3.version>
+        <org.assertj.core.version>3.9.0</org.assertj.core.version>
+        <commons-codec.version>1.11</commons-codec.version>
+        <junit-jupiter-api.version>5.3.1</junit-jupiter-api.version>
+    </properties>
+
+</project>

algorithms-sorting-2/src/main/java/com/baeldung/algorithms/quicksort/BentleyMcIlroyPartioning.java

@@ -0,0 +1,66 @@
+package com.baeldung.algorithms.quicksort;
+
+import static com.baeldung.algorithms.quicksort.SortingUtils.swap;
+
+public class BentleyMcIlroyPartioning {
+
+    public static Partition partition(int input[], int begin, int end) {
+        int left = begin, right = end;
+        int leftEqualKeysCount = 0, rightEqualKeysCount = 0;
+
+        int partitioningValue = input[end];
+
+        while (true) {
+            while (input[left] < partitioningValue)
+                left++;
+
+            while (input[right] > partitioningValue) {
+                if (right == begin)
+                    break;
+                right--;
+            }
+
+            if (left == right && input[left] == partitioningValue) {
+                swap(input, begin + leftEqualKeysCount, left);
+                leftEqualKeysCount++;
+                left++;
+            }
+
+            if (left >= right) {
+                break;
+            }
+
+            swap(input, left, right);
+
+            if (input[left] == partitioningValue) {
+                swap(input, begin + leftEqualKeysCount, left);
+                leftEqualKeysCount++;
+            }
+
+            if (input[right] == partitioningValue) {
+                swap(input, right, end - rightEqualKeysCount);
+                rightEqualKeysCount++;
+            }
+            left++; right--;
+        }
+        right = left - 1;
+        for (int k = begin; k < begin + leftEqualKeysCount; k++, right--) {
+            if (right >= begin + leftEqualKeysCount)
+                swap(input, k, right);
+        }
+        for (int k = end; k > end - rightEqualKeysCount; k--, left++) {
+            if (left <= end - rightEqualKeysCount)
+                swap(input, left, k);
+        }
+        return new Partition(right + 1, left - 1);
+    }
+
+    public static void quicksort(int input[], int begin, int end) {
+        if (end <= begin)
+            return;
+        Partition middlePartition = partition(input, begin, end);
+        quicksort(input, begin, middlePartition.getLeft() - 1);
+        quicksort(input, middlePartition.getRight() + 1, end);
+    }
+
+}

algorithms-sorting-2/src/main/java/com/baeldung/algorithms/quicksort/DutchNationalFlagPartioning.java

@@ -0,0 +1,38 @@
+package com.baeldung.algorithms.quicksort;
+
+import static com.baeldung.algorithms.quicksort.SortingUtils.compare;
+import static com.baeldung.algorithms.quicksort.SortingUtils.swap;
+
+public class DutchNationalFlagPartioning {
+
+    public static Partition partition(int[] a, int begin, int end) {
+        int lt = begin, current = begin, gt = end;
+        int partitioningValue = a[begin];
+
+        while (current <= gt) {
+            int compareCurrent = compare(a[current], partitioningValue);
+            switch (compareCurrent) {
+                case -1:
+                    swap(a, current++, lt++);
+                    break;
+                case 0:
+                    current++;
+                    break;
+                case 1:
+                    swap(a, current, gt--);
+                    break;
+            }
+        }
+        return new Partition(lt, gt);
+    }
+
+    public static void quicksort(int[] input, int begin, int end) {
+        if (end <= begin)
+            return;
+
+        Partition middlePartition = partition(input, begin, end);
+
+        quicksort(input, begin, middlePartition.getLeft() - 1);
+        quicksort(input, middlePartition.getRight() + 1, end);
+    }
+}

algorithms-sorting-2/src/main/java/com/baeldung/algorithms/quicksort/Partition.java

@@ -0,0 +1,29 @@
+package com.baeldung.algorithms.quicksort;
+
+public class Partition {
+    private int left;
+    private int right;
+
+    public Partition(int left, int right) {
+        super();
+        this.left = left;
+        this.right = right;
+    }
+
+    public int getLeft() {
+        return left;
+    }
+
+    public void setLeft(int left) {
+        this.left = left;
+    }
+
+    public int getRight() {
+        return right;
+    }
+
+    public void setRight(int right) {
+        this.right = right;
+    }
+
+}

algorithms-sorting-2/src/main/java/com/baeldung/algorithms/quicksort/SortingUtils.java

@@ -0,0 +1,32 @@
+package com.baeldung.algorithms.quicksort;
+
+public class SortingUtils {
+
+    public static void swap(int[] array, int position1, int position2) {
+        if (position1 != position2) {
+            int temp = array[position1];
+            array[position1] = array[position2];
+            array[position2] = temp;
+        }
+    }
+
+    public static int compare(int num1, int num2) {
+        if (num1 > num2)
+            return 1;
+        else if (num1 < num2)
+            return -1;
+        else
+            return 0;
+    }
+
+    public static void printArray(int[] array) {
+        if (array == null) {
+            return;
+        }
+        for (int e : array) {
+            System.out.print(e + " ");
+        }
+        System.out.println();
+    }
+
+}

algorithms-sorting-2/src/main/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT"/>
+    </root>
+</configuration>

algorithms-sorting-2/src/test/java/com/baeldung/algorithms/quicksort/BentleyMcilroyPartitioningUnitTest.java

@@ -0,0 +1,16 @@
+package com.baeldung.algorithms.quicksort;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class BentleyMcilroyPartitioningUnitTest {
+
+    @Test
+    public void given_IntegerArray_whenSortedWithBentleyMcilroyPartitioning_thenGetSortedArray() {
+        int[] actual = {3, 2, 2, 2, 3, 7, 7, 3, 2, 2, 7, 3, 3};
+        int[] expected = {2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 7, 7, 7};
+        BentleyMcIlroyPartioning.quicksort(actual, 0, actual.length - 1);
+        Assert.assertArrayEquals(expected, actual);
+    }
+
+}

algorithms-sorting-2/src/test/java/com/baeldung/algorithms/quicksort/DNFThreeWayQuickSortUnitTest.java

@@ -0,0 +1,15 @@
+package com.baeldung.algorithms.quicksort;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class DNFThreeWayQuickSortUnitTest {
+
+    @Test
+    public void givenIntegerArray_whenSortedWithThreeWayQuickSort_thenGetSortedArray() {
+        int[] actual = {3, 5, 5, 5, 3, 7, 7, 3, 5, 5, 7, 3, 3};
+        int[] expected = {3, 3, 3, 3, 3, 5, 5, 5, 5, 5, 7, 7, 7};
+        DutchNationalFlagPartioning.quicksort(actual, 0, actual.length - 1);
+        Assert.assertArrayEquals(expected, actual);
+    }
+}

apache-poi/pom.xml

@@ -32,7 +32,7 @@
     </dependencies>
 
     <properties>
-        <poi.version>3.15</poi.version>
+        <poi.version>4.1.1</poi.version>
         <jexcel.version>1.0.6</jexcel.version>
     </properties>
 

apache-poi/src/main/java/com/baeldung/poi/excel/ExcelCellFormatter.java

@@ -0,0 +1,20 @@
+package com.baeldung.poi.excel;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.DataFormatter;
+import org.apache.poi.ss.usermodel.FormulaEvaluator;
+import org.apache.poi.ss.usermodel.Workbook;
+
+public class ExcelCellFormatter {
+
+    public String getCellStringValue(Cell cell) {
+        DataFormatter formatter = new DataFormatter();
+        return formatter.formatCellValue(cell);
+    }
+
+    public String getCellStringValueWithFormula(Cell cell, Workbook workbook) {
+        DataFormatter formatter = new DataFormatter();
+        FormulaEvaluator evaluator = workbook.getCreationHelper().createFormulaEvaluator();
+        return formatter.formatCellValue(cell, evaluator);
+    }
+}

apache-poi/src/main/java/com/baeldung/poi/excel/read/cellvalueandnotformula/CellValueAndNotFormulaHelper.java

@@ -0,0 +1,83 @@
+package com.baeldung.poi.excel.read.cellvalueandnotformula;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.CellType;
+import org.apache.poi.ss.usermodel.FormulaEvaluator;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.ss.util.CellAddress;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+
+public class CellValueAndNotFormulaHelper {
+
+    public Object getCellValueByFetchingLastCachedValue(String fileLocation, String cellLocation) throws IOException {
+        Object cellValue = new Object();
+
+        FileInputStream inputStream = new FileInputStream(new File(fileLocation));
+        Workbook workbook = new XSSFWorkbook(inputStream);
+
+        Sheet sheet = workbook.getSheetAt(0);
+
+        CellAddress cellAddress = new CellAddress(cellLocation);
+        Row row = sheet.getRow(cellAddress.getRow());
+        Cell cell = row.getCell(cellAddress.getColumn());
+
+        if (cell.getCellType() == CellType.FORMULA) {
+            switch (cell.getCachedFormulaResultType()) {
+                case BOOLEAN:
+                    cellValue = cell.getBooleanCellValue();
+                    break;
+                case NUMERIC:
+                    cellValue = cell.getNumericCellValue();
+                    break;
+                case STRING:
+                    cellValue = cell.getStringCellValue();
+                    break;
+                default:
+                    cellValue = null;
+            }
+        }
+
+        workbook.close();
+        return cellValue;
+    }
+
+    public Object getCellValueByEvaluatingFormula(String fileLocation, String cellLocation) throws IOException {
+        Object cellValue = new Object();
+
+        FileInputStream inputStream = new FileInputStream(new File(fileLocation));
+        Workbook workbook = new XSSFWorkbook(inputStream);
+
+        Sheet sheet = workbook.getSheetAt(0);
+        FormulaEvaluator evaluator = workbook.getCreationHelper()
+            .createFormulaEvaluator();
+
+        CellAddress cellAddress = new CellAddress(cellLocation);
+        Row row = sheet.getRow(cellAddress.getRow());
+        Cell cell = row.getCell(cellAddress.getColumn());
+
+        if (cell.getCellType() == CellType.FORMULA) {
+            switch (evaluator.evaluateFormulaCell(cell)) {
+                case BOOLEAN:
+                    cellValue = cell.getBooleanCellValue();
+                    break;
+                case NUMERIC:
+                    cellValue = cell.getNumericCellValue();
+                    break;
+                case STRING:
+                    cellValue = cell.getStringCellValue();
+                    break;
+                default:
+                    cellValue = null;
+            }
+        }
+
+        workbook.close();
+        return cellValue;
+    }
+}

apache-poi/src/test/java/com/baeldung/poi/excel/ExcelCellFormatterUnitTest.java

@@ -0,0 +1,87 @@
+package com.baeldung.poi.excel;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.Before;
+import org.junit.Test;
+
+public class ExcelCellFormatterUnitTest {
+    private static final String FILE_NAME = "ExcelCellFormatterTest.xlsx";
+    private static final int STRING_CELL_INDEX = 0;
+    private static final int BOOLEAN_CELL_INDEX = 1;
+    private static final int RAW_NUMERIC_CELL_INDEX = 2;
+    private static final int FORMATTED_NUMERIC_CELL_INDEX = 3;
+    private static final int FORMULA_CELL_INDEX = 4;
+
+    private String fileLocation;
+
+    @Before
+    public void setup() throws IOException, URISyntaxException {
+            fileLocation = Paths.get(ClassLoader.getSystemResource(FILE_NAME).toURI()).toString();
+    }
+
+    @Test
+    public void givenStringCell_whenGetCellStringValue_thenReturnStringValue() throws IOException {
+        Workbook workbook = new XSSFWorkbook(fileLocation);
+        Sheet sheet = workbook.getSheetAt(0);
+        Row row = sheet.getRow(0);
+
+        ExcelCellFormatter formatter = new ExcelCellFormatter();
+        assertEquals("String Test", formatter.getCellStringValue(row.getCell(STRING_CELL_INDEX)));
+        workbook.close();
+    }
+
+    @Test
+    public void givenBooleanCell_whenGetCellStringValue_thenReturnBooleanStringValue() throws IOException {
+        Workbook workbook = new XSSFWorkbook(fileLocation);
+        Sheet sheet = workbook.getSheetAt(0);
+        Row row = sheet.getRow(0);
+
+        ExcelCellFormatter formatter = new ExcelCellFormatter();
+        assertEquals("TRUE", formatter.getCellStringValue(row.getCell(BOOLEAN_CELL_INDEX)));
+        workbook.close();
+    }
+
+    @Test
+    public void givenNumericCell_whenGetCellStringValue_thenReturnNumericStringValue() throws IOException {
+        Workbook workbook = new XSSFWorkbook(fileLocation);
+        Sheet sheet = workbook.getSheetAt(0);
+        Row row = sheet.getRow(0);
+
+        ExcelCellFormatter formatter = new ExcelCellFormatter();
+        assertEquals("1.234", formatter.getCellStringValue(row.getCell(RAW_NUMERIC_CELL_INDEX)));
+        assertEquals("1.23", formatter.getCellStringValue(row.getCell(FORMATTED_NUMERIC_CELL_INDEX)));
+        workbook.close();
+    }
+
+    @Test
+    public void givenFormualCell_whenGetCellStringValue_thenReturnOriginalFormulaString() throws IOException {
+        Workbook workbook = new XSSFWorkbook(fileLocation);
+        Sheet sheet = workbook.getSheetAt(0);
+        Row row = sheet.getRow(0);
+
+        ExcelCellFormatter formatter = new ExcelCellFormatter();
+        assertEquals("SUM(1+2)", formatter.getCellStringValue(row.getCell(FORMULA_CELL_INDEX)));
+        workbook.close();
+    }
+
+    @Test
+    public void givenFormualCell_whenGetCellStringValueForFormula_thenReturnOriginalFormulatring() throws IOException {
+        Workbook workbook = new XSSFWorkbook(fileLocation);
+        Sheet sheet = workbook.getSheetAt(0);
+        Row row = sheet.getRow(0);
+
+        ExcelCellFormatter formatter = new ExcelCellFormatter();
+        assertEquals("3", formatter.getCellStringValueWithFormula(row.getCell(FORMULA_CELL_INDEX), workbook));
+        workbook.close();
+    }
+
+}

apache-poi/src/test/java/com/baeldung/poi/excel/read/cellvalueandnotformula/CellValueAndNotFormulaUnitTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.poi.excel.read.cellvalueandnotformula;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class CellValueAndNotFormulaUnitTest {
+
+    private CellValueAndNotFormulaHelper readCellValueAndNotFormulaHelper;
+    private String fileLocation;
+    private static final String FILE_NAME = "test.xlsx";
+
+    @Before
+    public void setup() throws URISyntaxException {
+        fileLocation = Paths.get(ClassLoader.getSystemResource(FILE_NAME).toURI()).toString();
+        readCellValueAndNotFormulaHelper = new CellValueAndNotFormulaHelper();
+    }
+
+    @Test
+    public void givenExcelCell_whenReadCellValueByLastCachedValue_thenProduceCorrectResult() throws IOException {
+        final double expectedResult = 7.0;
+        final Object cellValue = readCellValueAndNotFormulaHelper.getCellValueByFetchingLastCachedValue(fileLocation, "C2");
+
+        assertEquals(expectedResult, cellValue);
+    }
+
+    @Test
+    public void givenExcelCell_whenReadCellValueByEvaluatingFormula_thenProduceCorrectResult() throws IOException {
+        final double expectedResult = 7.0;
+        final Object cellValue = readCellValueAndNotFormulaHelper.getCellValueByEvaluatingFormula(fileLocation, "C2");
+
+        assertEquals(expectedResult, cellValue);
+    }
+}

apache-rocketmq/README.md

@@ -0,0 +1,5 @@
+## Apache RocketMQ
+
+This module contains articles about Apache RocketMQ
+
+### Relevant Articles: 

apache-rocketmq/pom.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>apache-rocketmq</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <name>apache-rocketmq</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.rocketmq</groupId>
+            <artifactId>rocketmq-spring-boot-starter</artifactId>
+            <version>2.0.4</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <geode.core>1.6.0</geode.core>
+    </properties>
+</project>

apache-rocketmq/src/main/java/com/baeldung/rocketmq/consumer/CartEventConsumer.java

@@ -0,0 +1,34 @@
+package com.baeldung.rocketmq.consumer;
+
+import com.baeldung.rocketmq.event.CartItemEvent;
+import org.apache.rocketmq.spring.annotation.RocketMQMessageListener;
+import org.apache.rocketmq.spring.core.RocketMQListener;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.stereotype.Service;
+
+@SpringBootApplication
+public class CartEventConsumer {
+
+    public static void main(String[] args) {
+        SpringApplication.run(CartEventConsumer.class, args);
+    }
+
+    @Service
+    @RocketMQMessageListener(topic = "cart-item-add-topic", consumerGroup = "cart-consumer_cart-item-add-topic")
+    public class CardItemAddConsumer implements RocketMQListener<CartItemEvent> {
+        public void onMessage(CartItemEvent addItemEvent) {
+            System.out.println("Adding item: " + addItemEvent);
+            // logic
+        }
+    }
+
+    @Service
+    @RocketMQMessageListener(topic = "cart-item-removed-topic", consumerGroup = "cart-consumer_cart-item-removed-topic")
+    public class CardItemRemoveConsumer implements RocketMQListener<CartItemEvent> {
+        public void onMessage(CartItemEvent removeItemEvent) {
+            System.out.println("Removing item: " + removeItemEvent);
+            // logic
+        }
+    }
+}

apache-rocketmq/src/main/java/com/baeldung/rocketmq/event/CartItemEvent.java

@@ -0,0 +1,32 @@
+package com.baeldung.rocketmq.event;
+
+public class CartItemEvent {
+    private String itemId;
+    private int quantity;
+
+    public CartItemEvent(String itemId, int quantity) {
+        this.itemId = itemId;
+        this.quantity = quantity;
+    }
+
+    public String getItemId() {
+        return itemId;
+    }
+
+    public void setItemId(String itemId) {
+        this.itemId = itemId;
+    }
+
+    public int getQuantity() {
+        return quantity;
+    }
+
+    public void setQuantity(int quantity) {
+        this.quantity = quantity;
+    }
+
+    @Override
+    public String toString() {
+        return "CartItemEvent{" + "itemId='" + itemId + '\'' + ", quantity=" + quantity + '}';
+    }
+}

apache-rocketmq/src/main/java/com/baeldung/rocketmq/producer/CartEventProducer.java

@@ -0,0 +1,26 @@
+package com.baeldung.rocketmq.producer;
+
+
+import com.baeldung.rocketmq.event.CartItemEvent;
+import org.apache.rocketmq.spring.core.RocketMQTemplate;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class CartEventProducer implements CommandLineRunner {
+
+    @Autowired
+    private RocketMQTemplate rocketMQTemplate;
+
+    public static void main(String[] args) {
+        SpringApplication.run(CartEventProducer.class, args);
+    }
+
+    public void run(String... args) throws Exception {
+        rocketMQTemplate.convertAndSend("cart-item-add-topic", new CartItemEvent("bike", 1));
+        rocketMQTemplate.convertAndSend("cart-item-add-topic", new CartItemEvent("computer", 2));
+        rocketMQTemplate.convertAndSend("cart-item-removed-topic", new CartItemEvent("bike", 1));
+    }
+}