Merge remote-tracking branch 'origin/PR-7005' into PR-7005

.github/ISSUE_TEMPLATE/issue_report.md

@@ -0,0 +1,32 @@
+---
+name: Issue Report
+about: Report an issue to help us improve
+title: '[ISSUE] '
+---
+
+**Article and Module Links**
+A link to the affected article and the affected module. You can find the link to the module in the Conclusion section in the "on Github" standard phase.
+
+**Describe the Issue**
+A clear and concise description of what the issue is.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected Behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Environment (please complete the following information):**
+- OS: [e.g. Windows]
+- Browser [e.g. chrome, safari]
+- Version [e.g. 22]
+
+**Additional Context**
+Add any other context about the issue here.

CONTRIBUTING.md

@@ -0,0 +1,11 @@
+# Contributing to Baeldung Tutorials
+First off, thank you for considering contributing to Baeldung Tutorials.
+
+## Reporting Issues
+Before you submit an issue, please review the guidelines below:
+
+1. **No Custom Modifications:** If your issue arises from any custom modifications you've made to the code in the repository, we won't be able to assist. We can only help if the issue is reproducible with the untouched codebase from this repo. If you're working with a modified version, consider asking for help on StackOverflow or other relevant forums.
+2. **Use a clear and descriptive title** for the issue to identify the problem.
+3. **Include a link to the article** you're having issues with.
+4. **Describe the exact steps which reproduce the problem** in as many details as possible.
+5. **Additional Details:** Offer any other context or descriptions that could be useful. Screenshots, error messages, copy/pasteable snippets, or logs can be immensely helpful.

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/rotatearray/RotateArray.java

@@ -0,0 +1,102 @@
+package com.baeldung.algorithms.rotatearray;
+
+/**
+ *  To speed up the rotation, we narrow k rotations to the remainder of k divided by the array length, or k module the array length.
+ *  Therefore, a large rotation number will be translated into the relative smallest rotation.
+ *  All solutions replace the original array, although they might use an extra array to compute the rotation.
+ */
+public class RotateArray {
+
+    private RotateArray() {
+        throw new IllegalStateException("Rotate array algorithm utility methods class");
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void bruteForce(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        k %= arr.length;
+        int temp;
+        int previous;
+        for (int i = 0; i < k; i++) {
+            previous = arr[arr.length - 1];
+            for (int j = 0; j < arr.length; j++) {
+                temp = arr[j];
+                arr[j] = previous;
+                previous = temp;
+            }
+        }
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void withExtraArray(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        int[] extraArray = new int[arr.length];
+        for (int i = 0; i < arr.length; i++) {
+            extraArray[(i + k) % arr.length] = arr[i];
+        }
+        System.arraycopy(extraArray, 0, arr, 0, arr.length);
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void cyclicReplacement(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        k = k % arr.length;
+        int count = 0;
+        for (int start = 0; count < arr.length; start++) {
+            int current = start;
+            int prev = arr[start];
+            do {
+                int next = (current + k) % arr.length;
+                int temp = arr[next];
+                arr[next] = prev;
+                prev = temp;
+                current = next;
+                count++;
+            } while (start != current);
+        }
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void reverse(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        k %= arr.length;
+        reverse(arr, 0, arr.length - 1);
+        reverse(arr, 0, k - 1);
+        reverse(arr, k, arr.length - 1);
+    }
+
+    private static void reverse(int[] nums, int start, int end) {
+        while (start < end) {
+            int temp = nums[start];
+            nums[start] = nums[end];
+            nums[end] = temp;
+            start++;
+            end--;
+        }
+    }
+
+    private static void checkInvalidInput(int[] arr, int rotation) {
+        if (rotation < 1 || arr == null)
+            throw new IllegalArgumentException("Rotation must be greater than zero or array must be not null");
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/rotatearray/RotateArrayUnitTest.java

@@ -0,0 +1,124 @@
+package com.baeldung.algorithms.rotatearray;
+
+import static com.baeldung.algorithms.rotatearray.RotateArray.bruteForce;
+import static com.baeldung.algorithms.rotatearray.RotateArray.cyclicReplacement;
+import static com.baeldung.algorithms.rotatearray.RotateArray.reverse;
+import static com.baeldung.algorithms.rotatearray.RotateArray.withExtraArray;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+class RotateArrayUnitTest {
+
+    private final int[] arr = { 1, 2, 3, 4, 5, 6 };
+    private final int rotationLtArrayLength = 1;
+    private final int rotationGtArrayLength = arr.length + 2;
+    private final int[] ltArrayLengthRotation = { 6, 1, 2, 3, 4, 5 };
+    private final int[] gtArrayLengthRotation = { 5, 6, 1, 2, 3, 4 };
+
+    @Test
+    void givenInputArray_whenNoRotationOrEmptyArray_thenThrowIllegalArgumentException() {
+        final int noRotation = 0;
+        final int someRotation = arr.length - 1;
+
+        assertThrows(IllegalArgumentException.class, () -> bruteForce(arr, noRotation));
+        assertThrows(IllegalArgumentException.class, () -> withExtraArray(arr, noRotation));
+        assertThrows(IllegalArgumentException.class, () -> cyclicReplacement(arr, noRotation));
+        assertThrows(IllegalArgumentException.class, () -> reverse(arr, noRotation));
+
+        assertThrows(IllegalArgumentException.class, () -> bruteForce(null, someRotation));
+        assertThrows(IllegalArgumentException.class, () -> withExtraArray(null, someRotation));
+        assertThrows(IllegalArgumentException.class, () -> cyclicReplacement(null, someRotation));
+        assertThrows(IllegalArgumentException.class, () -> reverse(null, someRotation));
+    }
+
+    @Test
+    void givenInputArray_whenUseBruteForceRotationLtArrayLength_thenRotateArrayOk() {
+
+        bruteForce(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseBruteForceRotationGtArrayLength_thenRotateArrayOk() {
+
+        bruteForce(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseBruteForceRotationEqArrayLength_thenDoNothing() {
+        int[] expected = arr.clone();
+
+        bruteForce(arr, arr.length);
+        assertArrayEquals(expected, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseExtraArrayRotationLtArrayLength_thenRotateArrayOk() {
+
+        withExtraArray(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseExtraArrayRotationGtArrayLength_thenRotateArrayOk() {
+
+        withExtraArray(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseExtraArrayWithRotationEqArrayLength_thenDoNothing() {
+        int[] clone = arr.clone();
+
+        withExtraArray(arr, arr.length);
+        assertArrayEquals(clone, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseCyclicReplacementRotationLtArrayLength_thenRotateArrayOk() {
+
+        cyclicReplacement(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseCyclicReplacementRotationGtArrayLength_thenRotateArrayOk() {
+
+        cyclicReplacement(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseCyclicReplacementRotationEqArrayLength_thenDoNothing() {
+        int[] clone = arr.clone();
+
+        cyclicReplacement(arr, arr.length);
+        assertArrayEquals(clone, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseReverseRotationLtArrayLength_thenRotateArrayOk() {
+
+        reverse(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseReverseRotationGtArrayLength_thenRotateArrayOk() {
+
+        reverse(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseReverseRotationEqArrayLength_thenDoNothing() {
+
+        int[] clone = arr.clone();
+
+        reverse(arr, arr.length);
+        assertArrayEquals(clone, arr);
+    }
+}

apache-kafka-2/README.md

@@ -13,3 +13,4 @@ You can build the project from the command line using: *mvn clean install*, or i
 - [Read Data From the Beginning Using Kafka Consumer API](https://www.baeldung.com/java-kafka-consumer-api-read)
 - [Get Partition Count for a Topic in Kafka](https://www.baeldung.com/java-kafka-partition-count-topic)
 - [bootstrap-server in Kafka Configuration](https://www.baeldung.com/java-kafka-bootstrap-server)
+- [Introduction to Apache Kafka](https://www.baeldung.com/apache-kafka)

apache-kafka-2/src/test/java/com/baeldung/kafka/multipletopics/MultipleTopicsLiveTest.java

@@ -0,0 +1,103 @@
+package com.baeldung.kafka.multipletopics;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.Properties;
+import java.util.concurrent.ExecutionException;
+
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.apache.kafka.common.serialization.StringDeserializer;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+// This live test needs a Docker Daemon running so that a kafka container can be created
+
+@Testcontainers
+public class MultipleTopicsLiveTest {
+
+    private final Logger log = LoggerFactory.getLogger(MultipleTopicsLiveTest.class);
+
+    private static final String CARD_PAYMENTS_TOPIC = "card-payments";
+    private static final String BANK_TRANSFERS_TOPIC = "bank-transfers";
+    private static KafkaProducer<String, String> producer;
+    private static KafkaConsumer<String, String> consumer;
+
+    @Container
+    private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
+
+    @BeforeAll
+    static void setup() {
+        KAFKA_CONTAINER.addExposedPort(9092);
+        producer = new KafkaProducer<>(getProducerProperties());
+        consumer = new KafkaConsumer<>(getConsumerProperties());
+    }
+
+    @AfterAll
+    static void destroy() {
+        KAFKA_CONTAINER.stop();
+    }
+
+    private static Properties getProducerProperties() {
+        Properties producerProperties = new Properties();
+        producerProperties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        producerProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        producerProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        return producerProperties;
+    }
+
+    private static Properties getConsumerProperties() {
+        Properties consumerProperties = new Properties();
+        consumerProperties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        consumerProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        consumerProperties.put(ConsumerConfig.GROUP_ID_CONFIG, "payments");
+        return consumerProperties;
+    }
+
+    @Test
+    void whenSendingMessagesOnTwoTopics_thenConsumerReceivesMessages() throws Exception {
+        publishMessages();
+
+        consumer.subscribe(Arrays.asList(CARD_PAYMENTS_TOPIC, BANK_TRANSFERS_TOPIC));
+
+        int eventsProcessed = 0;
+        for (ConsumerRecord<String, String> record : consumer.poll(Duration.ofSeconds(10))) {
+            log.info("Event on topic={}, payload={}", record.topic(), record.value());
+            eventsProcessed++;
+        }
+
+        assertThat(eventsProcessed).isEqualTo(2);
+    }
+
+    private void publishMessages() throws ExecutionException, InterruptedException {
+        ProducerRecord<String, String> cardPayment = new ProducerRecord<>(CARD_PAYMENTS_TOPIC, createCardPayment());
+        producer.send(cardPayment).get();
+
+        ProducerRecord<String, String> bankTransfer = new ProducerRecord<>(BANK_TRANSFERS_TOPIC, createBankTransfer());
+        producer.send(bankTransfer).get();
+    }
+
+    private String createCardPayment() {
+        return "{\"paymentReference\":\"A184028KM0013790\", \"type\":\"card\", \"amount\":\"275\", \"currency\":\"GBP\"}";
+    }
+
+    private String createBankTransfer() {
+        return "{\"paymentReference\":\"19ae2-18mk73-009\", \"type\":\"bank\", \"amount\":\"150\", \"currency\":\"EUR\"}";
+    }
+}

apache-poi-3/README.md

@@ -0,0 +1,3 @@
+## Relevant Articles
+- [How To Convert Excel Data Into List Of Java Objects](https://www.baeldung.com/java-convert-excel-data-into-list)
+- [Expand Columns with Apache POI](https://www.baeldung.com/java-apache-poi-expand-columns)

apache-poi-3/pom.xml

@@ -0,0 +1,97 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>apache-poi-3</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>apache-poi-3</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.poi</groupId>
+            <artifactId>poi-ooxml</artifactId>
+            <version>${poi.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.poi</groupId>
+            <artifactId>poi-scratchpad</artifactId>
+            <version>${poi.version}</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/com.github.ozlerhakan/poiji -->
+        <dependency>
+            <groupId>com.github.ozlerhakan</groupId>
+            <artifactId>poiji</artifactId>
+            <version>${poiji.version}</version>
+        </dependency>
+
+        <!-- https://mvnrepository.com/artifact/org.apache.poi/poi/5.2.3 -->
+        <dependency>
+            <groupId>org.apache.poi</groupId>
+            <artifactId>poi</artifactId>
+            <version>${poi.version}</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml-schemas/4.1.2 -->
+        <dependency>
+            <groupId>org.apache.poi</groupId>
+            <artifactId>poi-ooxml-schemas</artifactId>
+            <version>4.1.2</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.apache.xmlbeans/xmlbeans/5.1.1 -->
+        <dependency>
+            <groupId>org.apache.xmlbeans</groupId>
+            <artifactId>xmlbeans</artifactId>
+            <version>5.1.1</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-collections4 -->
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>4.4</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.dhatim/fastexcel/0.15.7 -->
+        <dependency>
+            <groupId>org.dhatim</groupId>
+            <artifactId>fastexcel</artifactId>
+            <version>${fastexcel.version}</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.dhatim/fastexcel-reader/0.15.7 -->
+        <dependency>
+            <groupId>org.dhatim</groupId>
+            <artifactId>fastexcel-reader</artifactId>
+            <version>${fastexcel.version}</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/net.sourceforge.jexcelapi/jxl/2.6.12 -->
+        <dependency>
+            <groupId>net.sourceforge.jexcelapi</groupId>
+            <artifactId>jxl</artifactId>
+            <version>${jxl.version}</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.apache.logging.log4j/log4j-api -->
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-api</artifactId>
+            <version>2.17.1</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.apache.logging.log4j/log4j-core -->
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-core</artifactId>
+            <version>2.17.1</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <poi.version>5.2.3</poi.version>
+        <poiji.version>4.1.1</poiji.version>
+        <fastexcel.version>0.15.7</fastexcel.version>
+        <jxl.version>2.6.12</jxl.version>
+    </properties>
+
+</project>

apache-poi-3/src/main/java/com/baeldung/convert/exceldatatolist/FoodInfo.java

@@ -0,0 +1,54 @@
+package com.baeldung.convert.exceldatatolist;
+
+import com.poiji.annotation.ExcelCellName;
+
+public class FoodInfo {
+
+    @ExcelCellName("Category")
+    private String category; //food category
+    @ExcelCellName("Name")
+    private String name; // food name
+    @ExcelCellName("Measure")
+    private String measure;
+    @ExcelCellName("Calories")
+    private double calories; //amount of calories in kcal/measure
+
+    @Override
+    public String toString() {
+        return "FoodInfo{" + "category='" + category + '\'' + ", name='" + name + '\'' + ", measure='" + measure + '\'' + ", calories=" + calories + "} \n";
+    }
+
+
+    public String getCategory() {
+        return category;
+    }
+
+    public void setCategory(String category) {
+        this.category = category;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getMeasure() {
+        return measure;
+    }
+
+    public void setMeasure(String measure) {
+        this.measure = measure;
+    }
+
+    public double getCalories() {
+        return calories;
+    }
+
+    public void setCalories(double calories) {
+        this.calories = calories;
+    }
+
+}

apache-poi-3/src/main/java/com/baeldung/convert/exceldatatolist/fastexcel/ExcelDataToListOfObjectsFastExcel.java

@@ -0,0 +1,42 @@
+package com.baeldung.convert.exceldatatolist.fastexcel;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.dhatim.fastexcel.reader.ReadableWorkbook;
+import org.dhatim.fastexcel.reader.Row;
+import org.dhatim.fastexcel.reader.Sheet;
+
+import com.baeldung.convert.exceldatatolist.FoodInfo;
+
+public class ExcelDataToListOfObjectsFastExcel {
+    public static List<FoodInfo> excelDataToListOfObjets_withFastExcel(String fileLocation)throws IOException, NumberFormatException {
+        List<FoodInfo> foodData = new ArrayList<FoodInfo>();
+
+        try (FileInputStream file = new FileInputStream(fileLocation);
+            ReadableWorkbook wb = new ReadableWorkbook(file)) {
+            Sheet sheet = wb.getFirstSheet();
+            for (Row row:
+                sheet.read()
+            ) {
+                if(row.getRowNum() == 1) {
+                    continue;
+                }
+                FoodInfo food = new FoodInfo();
+                food.setCategory(row.getCellText(0));
+                food.setName(row.getCellText(1));
+                food.setMeasure(row.getCellText(2));
+                food.setCalories(Double.parseDouble(row.getCellText(3)));
+
+                foodData.add(food);
+
+            }
+        }
+
+        return foodData;
+    }
+}

apache-poi-3/src/main/java/com/baeldung/convert/exceldatatolist/jexcelapi/ExcelDataToListOfObjectsJxl.java

@@ -0,0 +1,37 @@
+package com.baeldung.convert.exceldatatolist.jexcelapi;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+import com.baeldung.convert.exceldatatolist.FoodInfo;
+
+import jxl.Sheet;
+import jxl.Workbook;
+import jxl.read.biff.BiffException;
+
+public class ExcelDataToListOfObjectsJxl {
+    public static List<FoodInfo> excelDataToListOfObjets_withJxl(String fileLocation) throws IOException, BiffException {
+
+        List<FoodInfo> foodData = new ArrayList<FoodInfo>();
+
+        Workbook workbook = Workbook.getWorkbook(new File(fileLocation));
+        Sheet sheet = workbook.getSheet(0);
+
+        int rows = sheet.getRows();
+
+        for (int i = 1; i < rows; i++) {
+            FoodInfo foodInfo = new FoodInfo();
+
+            foodInfo.setCategory(sheet.getCell(0, i).getContents());
+            foodInfo.setName(sheet.getCell(1, i).getContents());
+            foodInfo.setMeasure(sheet.getCell(2, i).getContents());
+            foodInfo.setCalories(Double.parseDouble(sheet.getCell(3, i).getContents()));
+           
+            foodData.add(foodInfo);
+
+        }
+        return foodData;
+    }
+}

apache-poi-3/src/main/java/com/baeldung/convert/exceldatatolist/poi/ExcelDataToListApachePOI.java

@@ -0,0 +1,39 @@
+package com.baeldung.convert.exceldatatolist.poi;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.poi.ss.usermodel.DataFormatter;
+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 com.baeldung.convert.exceldatatolist.FoodInfo;
+
+public class ExcelDataToListApachePOI {
+    public static List<FoodInfo> excelDataToListOfObjets_withApachePOI(String fileLocation) throws IOException {
+        FileInputStream file = new FileInputStream(new File(fileLocation));
+        Workbook workbook = new XSSFWorkbook(file);
+        Sheet sheet = workbook.getSheetAt(0);
+        List<FoodInfo> foodData = new ArrayList<FoodInfo>();
+        DataFormatter dataFormatter = new DataFormatter();
+        for (int n = 1; n < sheet.getPhysicalNumberOfRows(); n++) {
+            Row row = sheet.getRow(n);
+            FoodInfo foodInfo = new FoodInfo();
+            int i = row.getFirstCellNum();
+
+            foodInfo.setCategory(dataFormatter.formatCellValue(row.getCell(i)));
+            foodInfo.setName(dataFormatter.formatCellValue(row.getCell(++i)));
+            foodInfo.setMeasure(dataFormatter.formatCellValue(row.getCell(++i)));
+            foodInfo.setCalories(Double.parseDouble(dataFormatter.formatCellValue(row.getCell(++i))));
+
+            foodData.add(foodInfo);
+
+        }
+        return foodData;
+    }
+}

apache-poi-3/src/main/java/com/baeldung/convert/exceldatatolist/poiji/ExcelDataToListOfObjectsPOIJI.java

@@ -0,0 +1,13 @@
+package com.baeldung.convert.exceldatatolist.poiji;
+
+import java.io.File;
+import java.util.List;
+
+import com.baeldung.convert.exceldatatolist.FoodInfo;
+import com.poiji.bind.Poiji;
+
+public class ExcelDataToListOfObjectsPOIJI {
+    public static List<FoodInfo> excelDataToListOfObjets_withPOIJI(String fileLocation){
+        return Poiji.fromExcel(new File(fileLocation), FoodInfo.class);
+    }
+}

apache-poi-3/src/test/java/com/baeldung/convert/exceldatatolist/ExcelDataToListOfObjectsUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.convert.exceldatatolist;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.util.List;
+
+// import org.junit.jupiter.api.Test;
+// import static org.junit.jupiter.api.Assertions.*;
+import org.junit.Test;
+
+import com.baeldung.convert.exceldatatolist.fastexcel.ExcelDataToListOfObjectsFastExcel;
+import com.baeldung.convert.exceldatatolist.jexcelapi.ExcelDataToListOfObjectsJxl;
+import com.baeldung.convert.exceldatatolist.poi.ExcelDataToListApachePOI;
+import com.baeldung.convert.exceldatatolist.poiji.ExcelDataToListOfObjectsPOIJI;
+
+import jxl.read.biff.BiffException;
+
+public class ExcelDataToListOfObjectsUnitTest {
+
+    @Test
+    public void whenParsingExcelFileWithPOIJI_thenConvertsToList() throws IOException {
+        List<FoodInfo> foodInfoList = ExcelDataToListOfObjectsPOIJI.excelDataToListOfObjets_withPOIJI("src/main/resources/food_info.xlsx");
+
+        assertEquals("Beverages", foodInfoList.get(0).getCategory());
+        assertEquals("Dairy", foodInfoList.get(3).getCategory());
+    }
+
+    @Test
+    public void whenParsingExcelFileWithApachePOI_thenConvertsToList() throws IOException {
+        List<FoodInfo> foodInfoList = ExcelDataToListApachePOI.excelDataToListOfObjets_withApachePOI("src/main/resources/food_info.xlsx");
+
+        assertEquals("Beverages", foodInfoList.get(0).getCategory());
+        assertEquals("Dairy", foodInfoList.get(3).getCategory());
+    }
+
+    @Test
+    public void whenParsingExcelFileWithFastExcel_thenConvertsToList() throws IOException {
+        List<FoodInfo> foodInfoList = ExcelDataToListOfObjectsFastExcel.excelDataToListOfObjets_withFastExcel("src/main/resources/food_info.xlsx");
+
+        assertEquals("Beverages", foodInfoList.get(0).getCategory());
+        assertEquals("Dairy", foodInfoList.get(3).getCategory());
+    }
+
+    @Test
+    public void whenParsingExcelFileWithJxl_thenConvertsToList() throws IOException, BiffException {
+        List<FoodInfo> foodInfoList = ExcelDataToListOfObjectsJxl.excelDataToListOfObjets_withJxl("src/main/resources/food_info.xls");
+
+        assertEquals("Beverages", foodInfoList.get(0).getCategory());
+        assertEquals("Dairy", foodInfoList.get(3).getCategory());
+    }
+
+}

apache-poi-3/src/test/java/com/baeldung/poi/excel/expandcolumn/ExpandColumnUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.poi.excel.expandcolumn;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.io.IOException;
+
+import org.apache.poi.ss.usermodel.*;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class ExpandColumnUnitTest {
+
+    private Workbook workbook;
+    private Sheet sheet;
+
+    @BeforeEach
+    void prepareSpreadsheet() {
+        workbook = new XSSFWorkbook();
+        sheet = workbook.createSheet();
+
+        Row headerRow = sheet.createRow(0);
+        Cell headerCell1 = headerRow.createCell(0);
+        headerCell1.setCellValue("Full Name");
+        Cell headerCell2 = headerRow.createCell(1);
+        headerCell2.setCellValue("Abbreviation");
+
+        Row dataRow = sheet.createRow(1);
+        Cell dataCell1 = dataRow.createCell(0);
+        dataCell1.setCellValue("Java Virtual Machine");
+        Cell dataCell2 = dataRow.createCell(1);
+        dataCell2.setCellValue("JVM");
+
+        dataRow = sheet.createRow(2);
+        dataCell1 = dataRow.createCell(0);
+        dataCell1.setCellValue("Java Runtime Environment");
+        dataCell2 = dataRow.createCell(1);
+        dataCell2.setCellValue("JRE");
+    }
+
+    @Test
+    void whenSetColumnWidth_thenColumnSetToTheSpecifiedWidth() {
+
+        Row row = sheet.getRow(2);
+        String cellValue = row.getCell(0).getStringCellValue();
+        int targetWidth = cellValue.length() * 256;
+
+        sheet.setColumnWidth(0, targetWidth);
+
+        assertEquals(targetWidth, sheet.getColumnWidth(0));
+    }
+
+    @Test
+    void whenAutoSizeColumn_thenColumnExpands() {
+
+        int originalWidth = sheet.getColumnWidth(0);
+
+        sheet.autoSizeColumn(0);
+
+        assertThat(sheet.getColumnWidth(0)).isGreaterThan(originalWidth);
+    }
+
+    @AfterEach
+    void cleanup() throws IOException {
+        workbook.close();
+    }
+
+}

aws-modules/aws-s3/README.md

@@ -4,7 +4,7 @@ This module contains articles about Simple Storage Service (S3) on AWS
 
 ### Relevant articles
 
-- [AWS S3 with Java](https://www.baeldung.com/aws-s3-java)
+- [AWS S3 with Java](https://www.baeldung.com/java-aws-s3)
 - [Multipart Uploads in Amazon S3 with Java](https://www.baeldung.com/aws-s3-multipart-upload)
 - [Using the JetS3t Java Client With Amazon S3](https://www.baeldung.com/jets3t-amazon-s3)
 - [Check if a Specified Key Exists in a Given S3 Bucket Using Java](https://www.baeldung.com/java-aws-s3-check-specified-key-exists)

core-java-modules/core-java-16/README.md

@@ -5,3 +5,4 @@
 - [Collecting Stream Elements into a List in Java](https://www.baeldung.com/java-stream-to-list-collecting)
 - [New Features in Java 16](https://www.baeldung.com/java-16-new-features)
 - [Guide to Java 8 groupingBy Collector](https://www.baeldung.com/java-groupingby-collector)
+- [Value-Based Classes in Java](https://www.baeldung.com/java-value-based-classes)

core-java-modules/core-java-16/src/main/java/com/baeldung/value_based_class/Point.java

@@ -30,6 +30,11 @@ public final class Point {
         return new Point(x, y, z);
     }
 
+    @Override
+    public String toString() {
+        return "Point{" + "x=" + x + ", y=" + y + ", z=" + z + '}';
+    }
+
     @Override
     public boolean equals(Object other) {
         if (other == null || getClass() != other.getClass())

core-java-modules/core-java-16/src/test/java/com/baeldung/value_based_class/ValueBasedClassUnitTest.java

@@ -1,14 +1,17 @@
 package com.baeldung.value_based_class;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import org.junit.Assert;
 import org.junit.Test;
 
 public class ValueBasedClassUnitTest {
     @Test
     public void givenAutoboxedAndPrimitive_whenCompared_thenReturnEquals() {
-        int primitive_a = 125;
-        Integer obj_a = 125; // this is autoboxed
-        Assert.assertSame(primitive_a, obj_a);
+        List<Integer> list = new ArrayList<>();
+        list.add(1); // this is autoboxed
+        Assert.assertEquals(list.get(0), Integer.valueOf(1));
     }
 
     @Test

core-java-modules/core-java-18/pom.xml

@@ -0,0 +1,55 @@
+<?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>core-java-18</artifactId>
+    <name>core-java-18</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../../</relativePath>
+    </parent>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <release>${maven.compiler.release}</release>
+                    <compilerArgs>--enable-preview</compilerArgs>
+                    <source>${maven.compiler.source.version}</source>
+                    <target>${maven.compiler.target.version}</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>${surefire.plugin.version}</version>
+                <configuration>
+                    <forkCount>1</forkCount>
+                </configuration>
+                <dependencies>
+                    <dependency>
+                        <groupId>org.apache.maven.surefire</groupId>
+                        <artifactId>surefire-api</artifactId>
+                        <version>${surefire.plugin.version}</version>
+                    </dependency>
+                </dependencies>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <maven.compiler.source.version>18</maven.compiler.source.version>
+        <maven.compiler.target.version>18</maven.compiler.target.version>
+        <maven.compiler.release>18</maven.compiler.release>
+        <surefire.plugin.version>3.0.0-M5</surefire.plugin.version>
+    </properties>
+
+</project>

core-java-modules/core-java-18/src/main/java/com/baeldung/finalization_closeable_cleaner/FinalizationExamples.java

@@ -0,0 +1,27 @@
+package com.baeldung.finalization_closeable_cleaner;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+
+public class FinalizationExamples {
+    FileInputStream fis = null;
+
+    public void readFileOperationWithFinalization() throws IOException {
+        try {
+            fis = new FileInputStream("input.txt");
+            // perform operation on the file
+            System.out.println(fis.readAllBytes().length);
+
+        } finally {
+            if (fis != null)
+                fis.close();
+        }
+    }
+
+    public void readFileOperationWithTryWith() throws IOException {
+        try (FileInputStream fis = new FileInputStream("input.txt")) {
+            // perform operations
+            System.out.println(fis.readAllBytes().length);
+        }
+    }
+}

core-java-modules/core-java-18/src/main/java/com/baeldung/finalization_closeable_cleaner/MyCleanerResourceClass.java

@@ -0,0 +1,48 @@
+package com.baeldung.finalization_closeable_cleaner;
+
+import java.lang.ref.Cleaner;
+
+public class MyCleanerResourceClass implements AutoCloseable {
+    private static Resource resource;
+
+    private static final Cleaner cleaner = Cleaner.create();
+    private final Cleaner.Cleanable cleanable;
+
+    public MyCleanerResourceClass() {
+        resource = new Resource();
+        this.cleanable = cleaner.register(this, new CleaningState());
+    }
+
+    public void useResource() {
+        // using the resource here
+        resource.use();
+    }
+
+    @Override
+    public void close() {
+        // perform actions to close all underlying resources
+        this.cleanable.clean();
+    }
+
+    static class CleaningState implements Runnable {
+        CleaningState() {
+            // constructor
+        }
+
+        @Override
+        public void run() {
+            // some cleanup action
+            System.out.println("Cleanup done");
+        }
+    }
+
+    static class Resource {
+        void use() {
+            System.out.println("Using the resource");
+        }
+
+        void close() {
+            System.out.println("Cleanup done");
+        }
+    }
+}

core-java-modules/core-java-18/src/main/java/com/baeldung/finalization_closeable_cleaner/MyCloseableResourceClass.java

@@ -0,0 +1,25 @@
+package com.baeldung.finalization_closeable_cleaner;
+
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+public class MyCloseableResourceClass implements AutoCloseable {
+
+    private final FileInputStream fis;
+
+    public MyCloseableResourceClass() throws FileNotFoundException {
+        this.fis = new FileInputStream("src/main/resources/file.txt");
+
+    }
+
+    public int getByteLength() throws IOException {
+        System.out.println("Some operation");
+        return this.fis.readAllBytes().length;
+    }
+    @Override
+    public void close() throws IOException {
+        System.out.println("Finalized object");
+        this.fis.close();
+    }
+}

core-java-modules/core-java-18/src/main/java/com/baeldung/finalization_closeable_cleaner/MyFinalizableResourceClass.java

@@ -0,0 +1,24 @@
+package com.baeldung.finalization_closeable_cleaner;
+
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+public class MyFinalizableResourceClass {
+    private FileInputStream fis;
+
+    public MyFinalizableResourceClass() throws FileNotFoundException {
+        this.fis = new FileInputStream("src/main/resources/file.txt");
+    }
+
+    public int getByteLength() throws IOException {
+        System.out.println("Some operation");
+        return this.fis.readAllBytes().length;
+    }
+
+    @Override
+    protected void finalize() throws Throwable {
+        System.out.println("Finalized object");
+        this.fis.close();
+    }
+}

core-java-modules/core-java-18/src/main/resources/file.txt

@@ -0,0 +1 @@
+This is a test file.

core-java-modules/core-java-18/src/test/java/com/baeldung/finalization_closeable_cleaner/FinalizationCloseableCleanerUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.finalization_closeable_cleaner;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+import java.io.IOException;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FinalizationCloseableCleanerUnitTest {
+
+    @Test
+    public void givenMyFinalizationResource_whenUsingFinalize_thenShouldClean() {
+        assertDoesNotThrow(() -> {
+            MyFinalizableResourceClass mfr = new MyFinalizableResourceClass();
+            mfr.getByteLength();
+        });
+    }
+    @Test
+    public void givenMyCleanerResource_whenUsingCleanerAPI_thenShouldClean() {
+        assertDoesNotThrow(() -> {
+            try (MyCleanerResourceClass myCleanerResourceClass = new MyCleanerResourceClass()) {
+                myCleanerResourceClass.useResource();
+            }
+        });
+    }
+
+    @Test
+    public void givenCloseableResource_whenUsingTryWith_thenShouldClose() throws IOException {
+        int length = 0;
+        try (MyCloseableResourceClass mcr = new MyCloseableResourceClass()) {
+            length = mcr.getByteLength();
+        }
+        Assert.assertEquals(20, length);
+    }
+}

core-java-modules/core-java-21/README.md

@@ -1 +1,5 @@
-## Relevant Articles
+## Relevant Articles
+- [Sequenced Collections in Java 21](https://www.baeldung.com/java-21-sequenced-collections)
+- [String Templates in Java 21](https://www.baeldung.com/java-21-string-templates)
+- [Unnamed Classes and Instance Main Methods in Java 21](https://www.baeldung.com/java-21-unnamed-class-instance-main)
+- [Unnamed Patterns and Variables in Java 21](https://www.baeldung.com/java-unnamed-patterns-variables)