Merge branch 'eugenp:master' into master

algorithms-modules/algorithms-miscellaneous-7/README.md

@@ -5,4 +5,5 @@
 - [Getting Pixel Array From Image in Java](https://www.baeldung.com/java-getting-pixel-array-from-image)
 - [Calculate Distance Between Two Coordinates in Java](https://www.baeldung.com/java-find-distance-between-points)
 - [Rotate Arrays in Java](https://www.baeldung.com/java-rotate-arrays)
+- [Find Missing Number From a Given Array in Java](https://www.baeldung.com/java-array-find-missing-number)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-6)

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/weightedaverage/WeightedAverageUnitTest.java

@@ -0,0 +1,153 @@
+package com.baeldung.algorithms.weightedaverage;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.*;
+import java.util.function.BiConsumer;
+import java.util.function.BinaryOperator;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.Collector;
+import java.util.stream.IntStream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class WeightedAverageUnitTest {
+
+    private List<Values> values = Arrays.asList(
+            new Values(1, 10),
+            new Values(3, 20),
+            new Values(5, 30),
+            new Values(7, 50),
+            new Values(9, 40)
+    );
+
+    private Double expected = 6.2;
+
+    @Test
+    void twoPass() {
+        double top = values.stream()
+                .mapToDouble(v -> v.value * v.weight)
+                .sum();
+        double bottom = values.stream()
+                .mapToDouble(v -> v.weight)
+                .sum();
+
+        double result = top / bottom;
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void onePass() {
+        double top = 0;
+        double bottom = 0;
+
+        for (Values v : values) {
+            top += (v.value * v.weight);
+            bottom += v.weight;
+        }
+
+        double result = top / bottom;
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void expanding() {
+        double result = values.stream()
+                .flatMap(v -> Collections.nCopies(v.weight, v.value).stream())
+                .mapToInt(v -> v)
+                .average()
+                .getAsDouble();
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void reduce() {
+        class WeightedAverage {
+            final double top;
+            final double bottom;
+
+            public WeightedAverage(double top, double bottom) {
+                this.top = top;
+                this.bottom = bottom;
+            }
+
+            double average() {
+                return top / bottom;
+            }
+        }
+
+        double result = values.stream()
+                .reduce(new WeightedAverage(0, 0),
+                        (acc, next) -> new WeightedAverage(
+                                acc.top + (next.value * next.weight),
+                                acc.bottom + next.weight),
+                        (left, right) -> new WeightedAverage(
+                                left.top + right.top,
+                                left.bottom + right.bottom))
+                .average();
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void customCollector() {
+        class WeightedAverage implements Collector<Values, WeightedAverage.RunningTotals, Double> {
+            class RunningTotals {
+                double top;
+                double bottom;
+
+                public RunningTotals() {
+                    this.top = 0;
+                    this.bottom = 0;
+                }
+            }
+
+            @Override
+            public Supplier<RunningTotals> supplier() {
+                return RunningTotals::new;
+            }
+
+            @Override
+            public BiConsumer<RunningTotals, Values> accumulator() {
+                return (current, next) -> {
+                    current.top += (next.value * next.weight);
+                    current.bottom += next.weight;
+                };
+            }
+
+            @Override
+            public BinaryOperator<RunningTotals> combiner() {
+                return (left, right) -> {
+                    left.top += right.top;
+                    left.bottom += right.bottom;
+
+                    return left;
+                };
+            }
+
+            @Override
+            public Function<RunningTotals, Double> finisher() {
+                return rt -> rt.top / rt.bottom;
+            }
+
+            @Override
+            public Set<Characteristics> characteristics() {
+                return Collections.singleton(Characteristics.UNORDERED);
+            }
+        }
+
+        double result = values.stream()
+                .collect(new WeightedAverage());
+        assertEquals(expected, result);
+    }
+
+    private static class Values {
+        int value;
+        int weight;
+
+        public Values(int value, int weight) {
+            this.value = value;
+            this.weight = weight;
+        }
+    }
+}

apache-kafka-2/README.md

@@ -15,3 +15,4 @@ You can build the project from the command line using: *mvn clean install*, or i
 - [bootstrap-server in Kafka Configuration](https://www.baeldung.com/java-kafka-bootstrap-server)
 - [Introduction to Apache Kafka](https://www.baeldung.com/apache-kafka)
 - [Ensuring Message Ordering in Kafka: Strategies and Configurations](https://www.baeldung.com/kafka-message-ordering)
+- [Read Multiple Messages with Apache Kafka](https://www.baeldung.com/kafka-read-multiple-messages)

apache-poi-3/pom.xml

@@ -76,7 +76,7 @@
     </dependencies>
 
     <properties>
-        <poi.version>5.2.3</poi.version>
+        <poi.version>5.2.5</poi.version>
         <poiji.version>4.1.1</poiji.version>
         <fastexcel.version>0.15.7</fastexcel.version>
         <jxl.version>2.6.12</jxl.version>

apache-poi-3/src/main/java/com/baeldung/poi/rowstyle/PoiUtils.java

@@ -0,0 +1,53 @@
+package com.baeldung.poi.rowstyle;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.file.Path;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.CellStyle;
+import org.apache.poi.ss.usermodel.Font;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+
+public class PoiUtils {
+
+    private PoiUtils() {
+    }
+
+    private static void newCell(Row row, String value) {
+        short cellNum = row.getLastCellNum();
+        if (cellNum == -1)
+            cellNum = 0;
+
+        Cell cell = row.createCell(cellNum);
+        cell.setCellValue(value);
+    }
+
+    public static Row newRow(Sheet sheet, String... rowValues) {
+        Row row = sheet.createRow(sheet.getLastRowNum() + 1);
+
+        for (String value : rowValues) {
+            newCell(row, value);
+        }
+
+        return row;
+    }
+
+    public static CellStyle boldFontStyle(Workbook workbook) {
+        Font boldFont = workbook.createFont();
+        boldFont.setBold(true);
+
+        CellStyle boldStyle = workbook.createCellStyle();
+        boldStyle.setFont(boldFont);
+
+        return boldStyle;
+    }
+
+    public static void write(Workbook workbook, Path path) throws IOException {
+        try (FileOutputStream fileOut = new FileOutputStream(path.toFile())) {
+            workbook.write(fileOut);
+        }
+    }
+}

apache-poi-3/src/test/java/com/baeldung/poi/rowstyle/PoiBoldStyleIntegrationTest.java

@@ -0,0 +1,150 @@
+package com.baeldung.poi.rowstyle;
+
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import org.apache.poi.hssf.usermodel.HSSFCellStyle;
+import org.apache.poi.hssf.usermodel.HSSFWorkbook;
+import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
+import org.apache.poi.ss.usermodel.CellStyle;
+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.streaming.SXSSFWorkbook;
+import org.apache.poi.xssf.usermodel.XSSFCellStyle;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.jupiter.api.Test;
+
+class PoiBoldStyleIntegrationTest {
+
+    private void writeSampleSheet(Path destination, Workbook workbook) throws IOException {
+        Sheet sheet = workbook.createSheet();
+        CellStyle boldStyle = PoiUtils.boldFontStyle(workbook);
+
+        Row header = PoiUtils.newRow(sheet, "Name", "Value", "Details");
+        header.setRowStyle(boldStyle);
+
+        PoiUtils.newRow(sheet, "Albert", "A", "First");
+        PoiUtils.newRow(sheet, "Jane", "B", "Second");
+        PoiUtils.newRow(sheet, "Zack", "C", "Third");
+
+        PoiUtils.write(workbook, destination);
+    }
+
+    private void assertRowStyleAppliedAndDefaultCellStylesDontMatch(Path sheetFile) throws IOException, InvalidFormatException {
+        try (Workbook workbook = new XSSFWorkbook(sheetFile.toFile())) {
+            Sheet sheet = workbook.getSheetAt(0);
+            Row row0 = sheet.getRow(0);
+
+            XSSFCellStyle rowStyle = (XSSFCellStyle) row0.getRowStyle();
+            assertTrue(rowStyle.getFont()
+                .getBold());
+
+            row0.forEach(cell -> {
+                XSSFCellStyle style = (XSSFCellStyle) cell.getCellStyle();
+                assertNotEquals(rowStyle, style);
+            });
+
+            Row row1 = sheet.getRow(1);
+            XSSFCellStyle row1Style = (XSSFCellStyle) row1.getRowStyle();
+            assertNull(row1Style);
+
+            Files.delete(sheetFile);
+        }
+    }
+
+    @Test
+    void givenXssfWorkbook_whenSetRowStyle1stRow_thenOnly1stRowStyled() throws IOException, InvalidFormatException {
+        Path sheetFile = Files.createTempFile("xssf-row-style", ".xlsx");
+
+        try (Workbook workbook = new XSSFWorkbook()) {
+            writeSampleSheet(sheetFile, workbook);
+        }
+
+        assertRowStyleAppliedAndDefaultCellStylesDontMatch(sheetFile);
+    }
+
+    @Test
+    void givenSxssfWorkbook_whenSetRowStyle_thenOnly1stRowStyled() throws IOException, InvalidFormatException {
+        Path sheetFile = Files.createTempFile("sxssf-row-style", ".xlsx");
+
+        try (Workbook workbook = new SXSSFWorkbook()) {
+            writeSampleSheet(sheetFile, workbook);
+        }
+
+        assertRowStyleAppliedAndDefaultCellStylesDontMatch(sheetFile);
+    }
+
+    @Test
+    void givenHssfWorkbook_whenSetRowStyle_thenOnly1stRowStyled() throws IOException {
+        Path sheetFile = Files.createTempFile("hssf-row-style", ".xls");
+
+        try (Workbook workbook = new HSSFWorkbook()) {
+            writeSampleSheet(sheetFile, workbook);
+        }
+
+        try (Workbook workbook = new HSSFWorkbook(Files.newInputStream(sheetFile))) {
+            Sheet sheet = workbook.getSheetAt(0);
+            Row row0 = sheet.getRow(0);
+
+            HSSFCellStyle rowStyle = (HSSFCellStyle) row0.getRowStyle();
+            assertTrue(rowStyle.getFont(workbook)
+                .getBold());
+
+            row0.forEach(cell -> {
+                HSSFCellStyle style = (HSSFCellStyle) cell.getCellStyle();
+                assertNotEquals(rowStyle, style);
+            });
+
+            Row row1 = sheet.getRow(1);
+            HSSFCellStyle row1Style = (HSSFCellStyle) row1.getRowStyle();
+            assertNull(row1Style);
+
+            Files.delete(sheetFile);
+        }
+    }
+
+    @Test
+    void givenXssfWorkbook_whenSetCellStyleForEachRow_thenAllCellsContainStyle() throws IOException, InvalidFormatException {
+        Path sheetFile = Files.createTempFile("xssf-cell-style", ".xlsx");
+
+        try (Workbook workbook = new XSSFWorkbook()) {
+            Sheet sheet = workbook.createSheet();
+            CellStyle boldStyle = PoiUtils.boldFontStyle(workbook);
+
+            Row header = PoiUtils.newRow(sheet, "Name", "Value", "Details");
+            header.forEach(cell -> cell.setCellStyle(boldStyle));
+
+            PoiUtils.newRow(sheet, "Albert", "A", "First");
+            PoiUtils.newRow(sheet, "Jane", "B", "Second");
+            PoiUtils.newRow(sheet, "Zack", "C", "Third");
+
+            PoiUtils.write(workbook, sheetFile);
+        }
+
+        try (Workbook workbook = new XSSFWorkbook(sheetFile.toFile())) {
+            Sheet sheet = workbook.getSheetAt(0);
+            Row row0 = sheet.getRow(0);
+
+            XSSFCellStyle rowStyle = (XSSFCellStyle) row0.getRowStyle();
+            assertNull(rowStyle);
+
+            row0.forEach(cell -> {
+                XSSFCellStyle style = (XSSFCellStyle) cell.getCellStyle();
+                assertTrue(style.getFont()
+                    .getBold());
+            });
+
+            Row row1 = sheet.getRow(1);
+            rowStyle = (XSSFCellStyle) row1.getRowStyle();
+            assertNull(rowStyle);
+
+            Files.delete(sheetFile);
+        }
+    }
+}

core-java-modules/core-java-21/src/main/java/com/baeldung/jfrview/JFRExample.java

@@ -0,0 +1,21 @@
+package com.baeldung.jfrview;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class JFRExample {
+    public static void main(String[] args) {
+        JFRExample se = new JFRExample();
+        se.insertToList(new ArrayList<>());
+    }
+
+    private void insertToList(List<Object> list) {
+        try {
+            while (true) {
+                list.add(new Object());
+            }
+        } catch (OutOfMemoryError e) {
+            System.out.println("Out of Memory. Exiting");
+        }
+    }
+}

core-java-modules/core-java-8-datetime-2/README.md

@@ -9,4 +9,6 @@
 - [Round the Date in Java](https://www.baeldung.com/java-round-the-date)
 - [Representing Furthest Possible Date in Java](https://www.baeldung.com/java-date-represent-max)
 - [Retrieving Unix Time in Java](https://www.baeldung.com/java-retrieve-unix-time)
+- [Calculate Months Between Two Dates in Java](https://www.baeldung.com/java-months-difference-two-dates)
+- [Format LocalDate to ISO 8601 With T and Z](https://www.baeldung.com/java-format-localdate-iso-8601-t-z)
 - [[<-- Prev]](/core-java-modules/core-java-datetime-java8-1)

core-java-modules/core-java-8-datetime-2/src/main/java/com/baeldung/daterangeoverlap/DateRangeOverlapChecker.java

@@ -0,0 +1,46 @@
+package com.baeldung.daterangeoverlap;
+
+import java.time.LocalDate;
+import java.util.Calendar;
+
+import org.joda.time.DateTime;
+import org.joda.time.Interval;
+
+public class DateRangeOverlapChecker {
+
+    public static boolean isOverlapUsingCalendarAndDuration(Calendar start1, Calendar end1, Calendar start2, Calendar end2) {
+        long overlap = Math.min(end1.getTimeInMillis(), end2.getTimeInMillis()) - Math.max(start1.getTimeInMillis(), start2.getTimeInMillis());
+        return overlap >= 0;
+    }
+
+    public static boolean isOverlapUsingLocalDateAndDuration(LocalDate start1, LocalDate end1, LocalDate start2, LocalDate end2) {
+        long overlap = Math.min(end1.toEpochDay(), end2.toEpochDay()) - Math.max(start1.toEpochDay(), start2.toEpochDay());
+        return overlap >= 0;
+    }
+
+    public static boolean isOverlapUsingJodaTime(DateTime start1, DateTime end1, DateTime start2, DateTime end2) {
+        Interval interval1 = new Interval(start1, end1);
+        Interval interval2 = new Interval(start2, end2);
+        return interval1.overlaps(interval2);
+    }
+
+    public static boolean isOverlapUsingCalendarAndCondition(Calendar start1, Calendar end1, Calendar start2, Calendar end2) {
+        return !(end1.before(start2) || start1.after(end2));
+    }
+
+    public static boolean isOverlapUsingLocalDateAndCondition(LocalDate start1, LocalDate end1, LocalDate start2, LocalDate end2) {
+        return !(end1.isBefore(start2) || start1.isAfter(end2));
+    }
+
+    public static boolean isOverlapUsingCalendarAndFindMin(Calendar start1, Calendar end1, Calendar start2, Calendar end2) {
+        long overlap1 = Math.min(end1.getTimeInMillis() - start1.getTimeInMillis(), end1.getTimeInMillis() - start2.getTimeInMillis());
+        long overlap2 = Math.min(end2.getTimeInMillis() - start2.getTimeInMillis(), end2.getTimeInMillis() - start1.getTimeInMillis());
+        return Math.min(overlap1, overlap2) / (24 * 60 * 60 * 1000) >= 0;
+    }
+
+    public static boolean isOverlapUsingLocalDateAndFindMin(LocalDate start1, LocalDate end1, LocalDate start2, LocalDate end2) {
+        long overlap1 = Math.min(end1.toEpochDay() - start1.toEpochDay(), end1.toEpochDay() - start2.toEpochDay());
+        long overlap2 = Math.min(end2.toEpochDay() - start2.toEpochDay(), end2.toEpochDay() - start1.toEpochDay());
+        return Math.min(overlap1, overlap2) >= 0;
+    }
+}

core-java-modules/core-java-8-datetime-2/src/test/java/com/baeldung/daterangeoverlap/DateRangeOverlapCheckerUnitTest.java

@@ -0,0 +1,158 @@
+package com.baeldung.daterangeoverlap;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.time.LocalDate;
+import java.util.Calendar;
+
+import org.joda.time.DateTime;
+import org.junit.Test;
+
+public class DateRangeOverlapCheckerUnitTest {
+
+    @Test
+    public void givenPartialOverlappingRanges_thenReturnsTrue() {
+        Calendar start1 = Calendar.getInstance();
+        start1.set(2024, 11, 15);
+        Calendar end1 = Calendar.getInstance();
+        end1.set(2024, 11, 20);
+
+        Calendar start2 = Calendar.getInstance();
+        start2.set(2024, 11, 18);
+        Calendar end2 = Calendar.getInstance();
+        end2.set(2024, 11, 22);
+
+        LocalDate startLD1 = LocalDate.of(2024, 12, 15);
+        LocalDate endLD1 = LocalDate.of(2024, 12, 20);
+
+        LocalDate startLD2 = LocalDate.of(2024, 12, 18);
+        LocalDate endLD2 = LocalDate.of(2024, 12, 22);
+
+        DateTime startJT1 = new DateTime(2024, 12, 15, 0, 0);
+        DateTime endJT1 = new DateTime(2024, 12, 20, 0, 0);
+
+        DateTime startJT2 = new DateTime(2024, 12, 18, 0, 0);
+        DateTime endJT2 = new DateTime(2024, 12, 22, 0, 0);
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingCalendarAndDuration(start1, end1, start2, end2));
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingLocalDateAndDuration(startLD1, endLD1, startLD2, endLD2));
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingCalendarAndCondition(start1, end1, start2, end2));
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingLocalDateAndCondition(startLD1, endLD1, startLD2, endLD2));
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingCalendarAndFindMin(start1, end1, start2, end2));
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingLocalDateAndFindMin(startLD1, endLD1, startLD2, endLD2));
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingJodaTime(startJT1, endJT1, startJT2, endJT2));
+    }
+
+    @Test
+    public void givenFullOverlappingRanges_thenReturnsTrue() {
+        Calendar start1 = Calendar.getInstance();
+        start1.set(2024, 11, 15);
+        Calendar end1 = Calendar.getInstance();
+        end1.set(2024, 11, 20);
+
+        Calendar start2 = Calendar.getInstance();
+        start2.set(2024, 11, 16);
+        Calendar end2 = Calendar.getInstance();
+        end2.set(2024, 11, 18);
+
+        LocalDate startLD1 = LocalDate.of(2024, 12, 15);
+        LocalDate endLD1 = LocalDate.of(2024, 12, 20);
+
+        LocalDate startLD2 = LocalDate.of(2024, 12, 16);
+        LocalDate endLD2 = LocalDate.of(2024, 12, 18);
+
+        DateTime startJT1 = new DateTime(2024, 12, 15, 0, 0);
+        DateTime endJT1 = new DateTime(2024, 12, 20, 0, 0);
+
+        DateTime startJT2 = new DateTime(2024, 12, 16, 0, 0);
+        DateTime endJT2 = new DateTime(2024, 12, 18, 0, 0);
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingCalendarAndDuration(start1, end1, start2, end2));
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingLocalDateAndDuration(startLD1, endLD1, startLD2, endLD2));
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingCalendarAndCondition(start1, end1, start2, end2));
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingLocalDateAndCondition(startLD1, endLD1, startLD2, endLD2));
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingCalendarAndFindMin(start1, end1, start2, end2));
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingLocalDateAndFindMin(startLD1, endLD1, startLD2, endLD2));
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingJodaTime(startJT1, endJT1, startJT2, endJT2));
+    }
+
+    @Test
+    public void givenConsecutiveRanges_thenReturnsFalse() {
+        Calendar start1 = Calendar.getInstance();
+        start1.set(2024, 11, 15);
+        Calendar end1 = Calendar.getInstance();
+        end1.set(2024, 11, 20);
+
+        Calendar start2 = Calendar.getInstance();
+        start2.set(2024, 11, 21);
+        Calendar end2 = Calendar.getInstance();
+        end2.set(2024, 11, 24);
+
+        LocalDate startLD1 = LocalDate.of(2024, 12, 15);
+        LocalDate endLD1 = LocalDate.of(2024, 12, 20);
+
+        LocalDate startLD2 = LocalDate.of(2024, 12, 21);
+        LocalDate endLD2 = LocalDate.of(2024, 12, 24);
+
+        DateTime startJT1 = new DateTime(2024, 12, 15, 0, 0);
+        DateTime endJT1 = new DateTime(2024, 12, 20, 0, 0);
+
+        DateTime startJT2 = new DateTime(2024, 12, 21, 0, 0);
+        DateTime endJT2 = new DateTime(2024, 12, 24, 0, 0);
+
+        assertFalse(DateRangeOverlapChecker.isOverlapUsingCalendarAndDuration(start1, end1, start2, end2));
+        assertFalse(DateRangeOverlapChecker.isOverlapUsingLocalDateAndDuration(startLD1, endLD1, startLD2, endLD2));
+
+        assertFalse(DateRangeOverlapChecker.isOverlapUsingCalendarAndCondition(start1, end1, start2, end2));
+        assertFalse(DateRangeOverlapChecker.isOverlapUsingLocalDateAndCondition(startLD1, endLD1, startLD2, endLD2));
+
+        assertFalse(DateRangeOverlapChecker.isOverlapUsingCalendarAndFindMin(start1, end1, start2, end2));
+        assertFalse(DateRangeOverlapChecker.isOverlapUsingLocalDateAndFindMin(startLD1, endLD1, startLD2, endLD2));
+
+        assertFalse(DateRangeOverlapChecker.isOverlapUsingJodaTime(startJT1, endJT1, startJT2, endJT2));
+    }
+
+    @Test
+    public void givenZeroRangeRanges_thenReturnsTrue() {
+        Calendar start1 = Calendar.getInstance();
+        start1.set(2024, 11, 15);
+        Calendar end1 = Calendar.getInstance();
+        end1.set(2024, 11, 20);
+
+        Calendar start2 = Calendar.getInstance();
+        start2.set(2024, 11, 20);
+        Calendar end2 = Calendar.getInstance();
+        end2.set(2024, 11, 20);
+
+        LocalDate startLD1 = LocalDate.of(2024, 12, 15);
+        LocalDate endLD1 = LocalDate.of(2024, 12, 20);
+
+        LocalDate startLD2 = LocalDate.of(2024, 12, 20);
+        LocalDate endLD2 = LocalDate.of(2024, 12, 20);
+
+        DateTime startJT1 = new DateTime(2024, 12, 15, 0, 0);
+        DateTime endJT1 = new DateTime(2024, 12, 20, 0, 0);
+
+        DateTime startJT2 = new DateTime(2024, 12, 20, 0, 0);
+        DateTime endJT2 = new DateTime(2024, 12, 20, 0, 0);
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingCalendarAndDuration(start1, end1, start2, end2));
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingLocalDateAndDuration(startLD1, endLD1, startLD2, endLD2));
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingCalendarAndCondition(start1, end1, start2, end2));
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingLocalDateAndCondition(startLD1, endLD1, startLD2, endLD2));
+
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingCalendarAndFindMin(start1, end1, start2, end2));
+        assertTrue(DateRangeOverlapChecker.isOverlapUsingLocalDateAndFindMin(startLD1, endLD1, startLD2, endLD2));
+
+        //the overlaps method considers two intervals as overlapping only if they have a non-zero duration.
+        assertFalse(DateRangeOverlapChecker.isOverlapUsingJodaTime(startJT1, endJT1, startJT2, endJT2));
+    }
+}

core-java-modules/core-java-8-datetime-2/src/test/java/com/baeldung/zoneoffsetandzoneidof/ZoneOffSetAndZoneIdOfUnitTest.java

@@ -0,0 +1,25 @@
+package com.baeldung.zoneoffsetandzoneidof;
+
+import org.junit.jupiter.api.Test;
+
+import java.time.OffsetDateTime;
+import java.time.ZoneId;
+import java.time.ZoneOffset;
+import java.time.ZonedDateTime;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ZoneOffSetAndZoneIdOfUnitTest {
+
+    @Test
+    public void givenOffsetDateTimeWithUTCZoneOffset_thenOffsetShouldBeUTC() {
+        OffsetDateTime dateTimeWithOffset = OffsetDateTime.now(ZoneOffset.UTC);
+        assertEquals(dateTimeWithOffset.getOffset(), ZoneOffset.UTC);
+    }
+
+    @Test
+    public void givenZonedDateTimeWithUTCZoneId_thenZoneShouldBeUTC() {
+        ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId.of("UTC"));
+        assertEquals(zonedDateTime.getZone(), ZoneId.of("UTC"));
+    }
+}

core-java-modules/core-java-char/src/test/java/com/baeldung/unicodechar/UnicodeCharFromCodePointHexStringUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.unicodechar;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class UnicodeCharFromCodePointHexStringUnitTest {
+    private static final String U_CHECK = "✅"; // U+2705
+    private static final String U_STRONG = "强"; // U+5F3A
+
+
+    @Test
+    void whenEscapeUAndNumberInString_thenGetExpectedUnicodeStr() {
+        String check = "\u2705";
+        assertEquals(U_CHECK, check);
+
+        String strong = "\u5F3A";
+        assertEquals(U_STRONG, strong);
+
+        // "A" U+0041
+        assertEquals("A", "\u0041");
+    }
+
+
+    @Test
+    void whenConcatUAndNumberAsString_thenDoNotGetExpectedUnicodeStr() {
+        String check = "\\u" + "2705";
+        assertEquals("\\u2705", check);
+
+        String strong = "\\u" + "5F3A";
+        assertEquals("\\u5F3A", strong);
+    }
+
+
+    @Test
+    void whenCastHexCodePointToCharAndConvertCharToString_thenGetExpectedUnicodeStr() {
+
+        int codePoint = Integer.parseInt("2705", 16); //Decimal int: 9989
+        char[] checkChar = Character.toChars(codePoint);
+        String check = String.valueOf(checkChar);
+        assertEquals(U_CHECK, check);
+
+        // For Java 11 and later versions
+        // assertEquals(U_CHECK, Character.toString(codePoint));
+
+        codePoint = Integer.parseInt("5F3A", 16); //Decimal int: 24378
+        char[] strongChar = Character.toChars(codePoint);
+        String strong = String.valueOf(strongChar);
+        assertEquals(U_STRONG, strong);
+
+        // For Java 11 and later versions
+        // assertEquals(U_STRONG, Character.toString(codePoint));
+    }
+
+    String stringFromCodePointHex(String codePointHex) {
+        int codePoint = Integer.parseInt(codePointHex, 16);
+
+        // For Java 11 and later versions: return Character.toString(codePoint)
+
+        char[] chars = Character.toChars(codePoint);
+        return String.valueOf(chars);
+    }
+
+    @Test
+    void whenUsingstringFromCodePointHex_thenGetExpectedUnicodeStr() {
+        assertEquals("A", stringFromCodePointHex("0041"));
+        assertEquals(U_CHECK, stringFromCodePointHex("2705"));
+        assertEquals(U_STRONG, stringFromCodePointHex("5F3A"));
+    }
+}

core-java-modules/core-java-collections-5/README.md

@@ -11,4 +11,6 @@
 - [Intro to Vector Class in Java](https://www.baeldung.com/java-vector-guide)
 - [HashSet toArray() Method in Java](https://www.baeldung.com/java-hashset-toarray)
 - [Time Complexity of Java Collections Sort in Java](https://www.baeldung.com/java-time-complexity-collections-sort)
+- [Check if List Contains at Least One Enum](https://www.baeldung.com/java-list-check-enum-presence)
+- [Comparison of for Loops and Iterators](https://www.baeldung.com/java-for-loops-vs-iterators)
 - More articles: [[<-- prev]](/core-java-modules/core-java-collections-4)

core-java-modules/core-java-collections-list-6/README.md

@@ -1,2 +1,5 @@
 ## Relevant Articles
 - [Check if a List Contains a String Element While Ignoring Case](https://www.baeldung.com/java-list-search-case-insensitive)
+- [Removing the Last Node in a Linked List](https://www.baeldung.com/java-linked-list-remove-last-element)
+- [Call a Method on Each Element of a List in Java](https://www.baeldung.com/java-call-method-each-list-item)
+- [Sorting One List Based on Another List in Java](https://www.baeldung.com/java-sorting-one-list-using-another)

core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/resetlistiterator/ResetListIteratorUnitTest.java

@@ -0,0 +1,46 @@
+package com.baeldung.resetlistiterator;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+import java.util.ListIterator;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+public class ResetListIteratorUnitTest {
+
+    private static final List<String> MY_LIST = List.of("A", "B", "C", "D", "E", "F", "G");
+
+    @Test
+    void whenRecreateAnListIterator_thenGetTheExpectedResult() {
+        ListIterator<String> lit = MY_LIST.listIterator();
+        lit.next();
+        lit.next();
+        lit.next();
+        lit.next();
+
+        lit = MY_LIST.listIterator();
+
+        assertFalse(lit.hasPrevious());
+        assertEquals("A", lit.next());
+    }
+
+    @Test
+    void whenBackwardIterationToTheFirst_thenGetTheExpectedResult() {
+        ListIterator<String> lit = MY_LIST.listIterator();
+        lit.next();
+        lit.next();
+        lit.next();
+        lit.next();
+
+
+        while (lit.hasPrevious()) {
+            lit.previous();
+        }
+
+        assertFalse(lit.hasPrevious());
+        assertEquals("A", lit.next());
+    }
+
+}

core-java-modules/core-java-collections-maps-7/README.md

@@ -5,6 +5,6 @@
 - [How to Get First or Last Entry From a LinkedHashMap in Java](https://www.baeldung.com/java-linkedhashmap-first-last-key-value-pair)
 - [How to Write and Read a File with a Java HashMap](https://www.baeldung.com/java-hashmap-write-read-file)
 - [Limiting the Max Size of a HashMap in Java](https://www.baeldung.com/java-hashmap-size-bound)
-- [How to Sort LinkedHashMap By Values in Java](https://www.baeldung.com/java-sort-linkedhashmap-using-values)
+- [How to Sort LinkedHashMap by Values in Java](https://www.baeldung.com/java-sort-linkedhashmap-using-values)
 - [How to Increment a Map Value in Java](https://www.baeldung.com/java-increment-map-value)
 - More articles: [[<-- prev]](/core-java-modules/core-java-collections-maps-6)

core-java-modules/core-java-concurrency-basic-2/README.md

@@ -12,4 +12,5 @@ This module contains articles about basic Java concurrency
 - [How to Get the Number of Threads in a Java Process](https://www.baeldung.com/java-get-number-of-threads)
 - [Set the Name of a Thread in Java](https://www.baeldung.com/java-set-thread-name)
 - [Thread vs. Single Thread Executor Service](https://www.baeldung.com/java-single-thread-executor-service)
+- [Difference Between a Future and a Promise in Java](https://www.baeldung.com/java-future-vs-promise-comparison)
 - [[<-- Prev]](../core-java-concurrency-basic)[[Next -->]](../core-java-concurrency-basic-3)

core-java-modules/core-java-concurrency-basic-3/README.md

@@ -13,4 +13,5 @@ This module contains articles about basic Java concurrency.
 - [Retry Logic with CompletableFuture](https://www.baeldung.com/java-completablefuture-retry-logic)
 - [Convert From List of CompletableFuture to CompletableFuture List](https://www.baeldung.com/java-completablefuture-list-convert)
 - [Synchronize a Static Variable Among Different Threads](https://www.baeldung.com/java-synchronize-static-variable-different-threads)
+- [Difference Between execute() and submit() in Executor Service](https://www.baeldung.com/java-execute-vs-submit-executor-service)
 - [[<-- Prev]](../core-java-concurrency-basic-2)

core-java-modules/core-java-date-operations-4/README.md

@@ -0,0 +1,5 @@
+## Core Date Operations (Part 4)
+This module contains articles about date operations in Java.
+
+### Relevant Articles:
+

core-java-modules/core-java-date-operations-4/pom.xml

@@ -0,0 +1,46 @@
+<?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-date-operations-4</artifactId>
+    <name>core-java-date-operations-4</name>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>11</source>
+                    <target>11</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>joda-time</groupId>
+            <artifactId>joda-time</artifactId>
+            <version>${joda-time.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <joda-time.version>2.12.6</joda-time.version>
+    </properties>
+
+</project>

core-java-modules/core-java-date-operations-4/src/main/java/com/baeldung/calculateweekdays/CalculateWeekdays.java

@@ -0,0 +1,46 @@
+package com.baeldung.calculateweekdays;
+
+import java.time.DayOfWeek;
+import java.time.LocalDate;
+import java.time.temporal.ChronoUnit;
+import java.time.temporal.TemporalAdjusters;
+import java.util.Arrays;
+
+public class CalculateWeekdays {
+
+    public long getWorkingDaysWithStream(LocalDate start, LocalDate end){
+        return start.datesUntil(end)
+          .map(LocalDate::getDayOfWeek)
+          .filter(day -> !Arrays.asList(DayOfWeek.SATURDAY, DayOfWeek.SUNDAY).contains(day))
+          .count();
+    }
+
+    public long getWorkingDaysWithoutStream(LocalDate start, LocalDate end) {
+        boolean startOnWeekend = false;
+
+        // If starting at the weekend, move to following Monday
+        if(start.getDayOfWeek().getValue() > 5){
+            start = start.with(TemporalAdjusters.next(DayOfWeek.MONDAY));
+            startOnWeekend = true;
+        }
+        boolean endOnWeekend = false;
+        // If ending at the weekend, move to previous Friday
+        if(end.getDayOfWeek().getValue() > 5){
+            end = end.with(TemporalAdjusters.previous(DayOfWeek.FRIDAY));
+            endOnWeekend = true;
+        }
+        // Cover case where starting on Saturday and ending following Sunday
+        if(start.isAfter(end)){
+            return 0;
+        }
+        // Get total weeks
+        long weeks = ChronoUnit.WEEKS.between(start, end);
+
+        long addValue = startOnWeekend || endOnWeekend ? 1 : 0;
+
+        // Add on days that did not make up a full week
+        return ( weeks * 5 ) + ( end.getDayOfWeek().getValue() - start.getDayOfWeek().getValue() ) + addValue;
+    }
+
+
+}

core-java-modules/core-java-date-operations-4/src/test/java/com/baeldung/calculateweekdays/CalculateWeekdaysUnitTest.java

@@ -0,0 +1,83 @@
+package com.baeldung.calculateweekdays;
+
+import static junit.framework.TestCase.assertEquals;
+
+import java.time.LocalDate;
+
+import org.junit.jupiter.api.Test;
+
+public class CalculateWeekdaysUnitTest {
+
+    // Start Saturday end following Sunday (answer is 0)
+    LocalDate startTomorrow = LocalDate.of(2023, 12, 2);
+    LocalDate endTomorrow = LocalDate.of(2023, 12, 3);
+
+    // Three week gap with midweek start and finish (answer is 17)
+    LocalDate startThreeWeeks = LocalDate.of(2023, 11, 28);
+    LocalDate endThreeWeeks = LocalDate.of(2023, 12, 21);
+
+    // Three week gap with midweek start and weekend finish (answer is 17)
+    LocalDate startThreeWeeks2 = LocalDate.of(2023, 11, 6);
+    LocalDate endThreeWeeks2 = LocalDate.of(2023, 12, 30);
+
+    // Week gap start and end on weekend (answer is 40)
+    LocalDate startThreeWeeksWeekend = LocalDate.of(2023, 12, 2);
+    LocalDate endThreeWeeksWeekend = LocalDate.of(2023, 12, 9);
+
+    @Test
+    void givenTwoDaysOnSameWeekend_whenUsingStreams_thenCalculateWeekdays(){
+        CalculateWeekdays c = new CalculateWeekdays();
+        long result = c.getWorkingDaysWithStream(startTomorrow, endTomorrow);
+        assertEquals(0, result);
+    }
+
+    @Test
+    void givenTwoDaysOnSameWeekend_whenUsingMaths_thenCalculateWeekdays(){
+        CalculateWeekdays c = new CalculateWeekdays();
+        long result = c.getWorkingDaysWithoutStream(startTomorrow, endTomorrow);
+        assertEquals(0, result);
+    }
+
+    @Test
+    void givenAThreeWeekGapMidweekDates_whenUsingStreams_thenCalculateWeekdays(){
+        CalculateWeekdays c = new CalculateWeekdays();
+        long result = c.getWorkingDaysWithStream(startThreeWeeks, endThreeWeeks);
+        assertEquals(17, result);
+    }
+
+    @Test
+    void givenAThreeWeekGapMidweekDates_whenUsingMaths_thenCalculateWeekdays(){
+        CalculateWeekdays c = new CalculateWeekdays();
+        long result = c.getWorkingDaysWithoutStream(startThreeWeeks, endThreeWeeks);
+        assertEquals(17, result);
+    }
+
+    @Test
+    void givenThreeWeekGapMidweekAndWeekendDates_whenUsingStreams_thenCalculateWeekdays(){
+        CalculateWeekdays c = new CalculateWeekdays();
+        long result = c.getWorkingDaysWithStream(startThreeWeeksWeekend, endThreeWeeksWeekend);
+        assertEquals(5, result);
+    }
+
+    @Test
+    void givenThreeWeekGapMidweekAndWeekendDates_whenUsingMaths_thenCalculateWeekdays(){
+        CalculateWeekdays c = new CalculateWeekdays();
+        long result = c.getWorkingDaysWithoutStream(startThreeWeeksWeekend, endThreeWeeksWeekend);
+        assertEquals(5, result);
+    }
+
+    @Test
+    void givenThreeWeekGapWeekendDates_whenUsingStreams_thenCalculateWeekdays(){
+        CalculateWeekdays c = new CalculateWeekdays();
+        long result = c.getWorkingDaysWithStream(startThreeWeeks2, endThreeWeeks2);
+        assertEquals(40, result);
+    }
+
+    @Test
+    void givenThreeWeekGapWeekendDates_whenUsingMaths_thenCalculateWeekdays(){
+        CalculateWeekdays c = new CalculateWeekdays();
+        long result = c.getWorkingDaysWithoutStream(startThreeWeeks2, endThreeWeeks2);
+        assertEquals(40, result);
+    }
+
+}

core-java-modules/core-java-date-operations-4/src/test/java/com/baeldung/longtodate/LongToDateUnitTest.java

@@ -0,0 +1,74 @@
+package com.baeldung.longtodate;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.LocalDate;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.TimeZone;
+
+import org.joda.time.DateTimeZone;
+import org.joda.time.Instant;
+import org.junit.jupiter.api.Test;
+
+class LongToDateUnitTest {
+
+    @Test
+    void givenLongValue_whenUsingInstantClass_thenConvert() {
+        Instant expectedDate = Instant.parse("2020-09-08T12:16:40Z");
+        long seconds = 1599567400L;
+
+        Instant date = Instant.ofEpochSecond(seconds);
+
+        assertEquals(expectedDate, date);
+    }
+
+    @Test
+    void givenLongValue_whenUsingLocalDateClass_thenConvert() {
+        LocalDate expectedDate = LocalDate.of(2023, 10, 17);
+        long epochDay = 19647L;
+
+        LocalDate date = LocalDate.ofEpochDay(epochDay);
+
+        assertEquals(expectedDate, date);
+    }
+
+    @Test
+    void givenLongValue_whenUsingDateClass_thenConvert() throws ParseException {
+        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+        dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
+        Date expectedDate = dateFormat.parse("2023-07-15 22:00:00");
+        long milliseconds = 1689458400000L;
+
+        Date date = new Date(milliseconds);
+
+        assertEquals(expectedDate, date);
+    }
+
+    @Test
+    void givenLongValue_whenUsingCalendarClass_thenConvert() throws ParseException {
+        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+        dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
+        Date expectedDate = dateFormat.parse("2023-07-15 22:00:00");
+        long milliseconds = 1689458400000L;
+
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTimeZone(TimeZone.getTimeZone("UTC"));
+        calendar.setTimeInMillis(milliseconds);
+
+        assertEquals(expectedDate, calendar.getTime());
+    }
+
+    @Test
+    void givenLongValue_whenUsingJodaTimeLocalDateClass_thenConvert() {
+        org.joda.time.LocalDate expectedDate = new org.joda.time.LocalDate(2023, 7, 15);
+        long milliseconds = 1689458400000L;
+
+        org.joda.time.LocalDate date = new org.joda.time.LocalDate(milliseconds, DateTimeZone.UTC);
+
+        assertEquals(expectedDate, date);
+    }
+
+}

core-java-modules/core-java-datetime-conversion-2/README.md

@@ -0,0 +1,6 @@
+## Java Date/time conversion Cookbooks and Examples
+
+This module contains articles about converting between Java date and time objects.
+
+### Relevant Articles: 
+

core-java-modules/core-java-datetime-conversion-2/pom.xml

@@ -0,0 +1,57 @@
+<?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-datetime-conversion-2</artifactId>
+    <version>${project.parent.version}</version>
+    <name>core-java-datetime-conversion-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>joda-time</groupId>
+            <artifactId>joda-time</artifactId>
+            <version>${joda-time.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.github.msarhan</groupId>
+            <artifactId>ummalqura-calendar</artifactId>
+            <version>${ummalqura-calendar.version}</version>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+        <finalName>core-java-datetime-conversion-2</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <joda-time.version>2.12.5</joda-time.version>
+        <ummalqura-calendar.version>2.0.2</ummalqura-calendar.version>
+    </properties>
+
+</project>

core-java-modules/core-java-datetime-conversion-2/src/main/java/com/baeldung/gregoriantohijri/GregorianToHijriDateConverter.java

@@ -0,0 +1,34 @@
+package com.baeldung.gregoriantohijri;
+
+import java.text.ParseException;
+import java.time.LocalDate;
+import java.time.chrono.ChronoLocalDate;
+import java.time.chrono.HijrahChronology;
+import java.time.chrono.HijrahDate;
+import java.util.GregorianCalendar;
+
+import org.joda.time.chrono.IslamicChronology;
+
+import com.github.msarhan.ummalqura.calendar.UmmalquraCalendar;
+
+public class GregorianToHijriDateConverter {
+    public static HijrahDate usingHijrahChronology(LocalDate gregorianDate) {
+        HijrahChronology hijrahChronology = HijrahChronology.INSTANCE;
+        ChronoLocalDate hijriChronoLocalDate = hijrahChronology.date(gregorianDate);
+        return HijrahDate.from(hijriChronoLocalDate);
+    }
+
+    public static HijrahDate usingFromMethod(LocalDate gregorianDate) {
+        return HijrahDate.from(gregorianDate);
+    }
+
+    public static org.joda.time.DateTime usingJodaDate(org.joda.time.DateTime gregorianDate) {
+        return gregorianDate.withChronology(IslamicChronology.getInstance());
+    }
+
+    public static UmmalquraCalendar usingUmmalquraCalendar(GregorianCalendar gregorianCalendar) throws ParseException {
+        UmmalquraCalendar hijriCalendar = new UmmalquraCalendar();
+        hijriCalendar.setTime(gregorianCalendar.getTime());
+        return hijriCalendar;
+    }
+}

core-java-modules/core-java-datetime-conversion-2/src/test/java/com/baeldung/gregoriantohijri/GregorianToHijriDateConverterUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.gregoriantohijri;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.text.ParseException;
+import java.time.LocalDate;
+import java.time.chrono.HijrahDate;
+import java.time.temporal.ChronoField;
+import java.util.Calendar;
+import java.util.GregorianCalendar;
+
+import org.joda.time.DateTime;
+import org.junit.jupiter.api.Test;
+
+import com.github.msarhan.ummalqura.calendar.UmmalquraCalendar;
+
+public class GregorianToHijriDateConverterUnitTest {
+        @Test
+        void givenGregorianDate_whenUsingHijrahChronologyClass_thenConvertHijriDate() {
+            LocalDate gregorianDate = LocalDate.of(2013, 3, 31);
+            HijrahDate hijriDate = GregorianToHijriDateConverter.usingHijrahChronology(gregorianDate);
+            assertEquals(1434, hijriDate.get(ChronoField.YEAR));
+            assertEquals(5, hijriDate.get(ChronoField.MONTH_OF_YEAR));
+            assertEquals(19, hijriDate.get(ChronoField.DAY_OF_MONTH));
+        }
+
+    @Test
+    void givenGregorianDate_whenUsingFromMethod_thenConvertHijriDate() {
+        LocalDate gregorianDate = LocalDate.of(2013, 3, 31);
+        HijrahDate hijriDate = GregorianToHijriDateConverter.usingFromMethod(gregorianDate);
+        assertEquals(1434, hijriDate.get(ChronoField.YEAR));
+        assertEquals(5, hijriDate.get(ChronoField.MONTH_OF_YEAR));
+        assertEquals(19, hijriDate.get(ChronoField.DAY_OF_MONTH));
+    }
+
+    @Test
+    void givenGregorianDate_whenUsingJodaDate_thenConvertHijriDate() {
+        DateTime gregorianDate = new DateTime(2013, 3, 31, 0, 0, 0);
+        DateTime hijriDate = GregorianToHijriDateConverter.usingJodaDate(gregorianDate);
+        assertEquals(1434, hijriDate.getYear());
+        assertEquals(5, hijriDate.getMonthOfYear());
+        assertEquals(19, hijriDate.getDayOfMonth());
+    }
+
+    @Test
+    void givenGregorianDate_whenUsingUmmalquraCalendar_thenConvertHijriDate() throws ParseException {
+        GregorianCalendar gregorianCalendar = new GregorianCalendar(2013, Calendar.MARCH, 31);
+        UmmalquraCalendar ummalquraCalendar = GregorianToHijriDateConverter.usingUmmalquraCalendar(gregorianCalendar);
+        assertEquals(1434, ummalquraCalendar.get(Calendar.YEAR));
+        assertEquals(5, ummalquraCalendar.get(Calendar.MONTH) + 1);
+        assertEquals(19, ummalquraCalendar.get(Calendar.DAY_OF_MONTH));
+    }
+}

core-java-modules/core-java-datetime-conversion/README.md

@@ -12,3 +12,4 @@ This module contains articles about converting between Java date and time object
 - [Convert Epoch Time to LocalDate and LocalDateTime](https://www.baeldung.com/java-convert-epoch-localdate)
 - [Convert Timestamp String to Long in Java](https://www.baeldung.com/java-convert-timestamp-string-long)
 - [Convert Long Timestamp to LocalDateTime in Java](https://www.baeldung.com/java-convert-long-timestamp-localdatetime)
+- [Convert Joda-Time DateTime to Date and Vice Versa](https://www.baeldung.com/java-convert-joda-time-datetime-to-date)

core-java-modules/core-java-datetime-string-2/pom.xml

@@ -13,6 +13,14 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
+    <dependencies>
+        <dependency>
+            <groupId>joda-time</groupId>
+            <artifactId>joda-time</artifactId>
+            <version>${joda-time.version}</version>
+        </dependency>
+    </dependencies>
+
     <build>
         <plugins>
             <plugin>
@@ -22,4 +30,8 @@
         </plugins>
     </build>
 
+    <properties>
+        <joda-time.version>2.12.5</joda-time.version>
+    </properties>
+
 </project>

core-java-modules/core-java-datetime-string-2/src/test/java/com/baeldung/timestamp/CurrentTimeAsFileNameUnitTest.java

@@ -0,0 +1,114 @@
+package com.baeldung.timestamp;
+
+import static org.junit.Assert.assertTrue;
+
+import java.text.MessageFormat;
+import java.text.SimpleDateFormat;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneId;
+import java.time.ZoneOffset;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.ChronoUnit;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.regex.Pattern;
+
+import org.joda.time.DateTime;
+import org.joda.time.format.DateTimeFormat;
+import org.junit.Test;
+
+public class CurrentTimeAsFileNameUnitTest {
+
+    static final String TIMESTAMP_FORMAT = "yyyyMMddHHmmss";
+    static final DateTimeFormatter DATETIME_FORMATTER = DateTimeFormatter.ofPattern(TIMESTAMP_FORMAT);
+    static final SimpleDateFormat SIMPLEDATE_FORMAT = new SimpleDateFormat(TIMESTAMP_FORMAT);
+
+    @Test
+    public void whenUsingCalendar_thenCurrentTimeAsFileName() {
+        String currentTime = SIMPLEDATE_FORMAT.format(Calendar.getInstance().getTime());
+        String fileName = getFileName(currentTime);
+
+        assertTrue(verifyFileName(fileName));
+    }
+
+    @Test
+    public void whenUsingDate_thenCurrentTimeAsFileName() {
+        String currentTime = SIMPLEDATE_FORMAT.format(new Date());
+        String fileName = getFileName(currentTime);
+
+        assertTrue(verifyFileName(fileName));
+    }
+
+    @Test
+    public void whenUsingInstant_thenCurrentTimeAsFileName() {
+        String currentTime = Instant
+            .now()
+            .truncatedTo(ChronoUnit.SECONDS)
+            .toString()
+            .replaceAll("[:TZ-]", "");
+        String fileName = getFileName(currentTime);
+
+        assertTrue(verifyFileName(fileName));
+    }
+
+    @Test
+    public void whenUsingLocalDateTime_thenCurrentTimeAsFileName() {
+        String currentTime = LocalDateTime.now().format(DATETIME_FORMATTER);
+        String fileName = getFileName(currentTime);
+
+        assertTrue(verifyFileName(fileName));
+    }
+
+    @Test
+    public void whenUsingZonedDateTime_thenCurrentTimeAsFileName() {
+        String currentTime = ZonedDateTime
+            .now(ZoneId.of("Europe/Paris"))
+            .format(DATETIME_FORMATTER);
+        String fileName = getFileName(currentTime);
+
+        assertTrue(verifyFileName(fileName));
+    }
+
+    @Test
+    public void whenUsingOffsetDateTime_thenCurrentTimeAsFileName() {
+        String currentTime = OffsetDateTime
+            .of(LocalDateTime.now(), ZoneOffset.of("+01:00"))
+            .format(DATETIME_FORMATTER);
+        String fileName = getFileName(currentTime);
+
+        assertTrue(verifyFileName(fileName));
+    }
+
+    @Test
+    public void whenUsingJodaDateTime_thenCurrentTimeAsFileName() {
+        String currentTime = DateTime.now().toString(TIMESTAMP_FORMAT);
+        String fileName = getFileName(currentTime);
+
+        assertTrue(verifyFileName(fileName));
+    }
+
+    @Test
+    public void whenUsingJodaInstant_thenCurrentTimeAsFileName() {
+        String currentTime = DateTimeFormat
+            .forPattern(TIMESTAMP_FORMAT)
+            .print(org.joda.time.Instant.now()
+                .toDateTime());
+        String fileName = getFileName(currentTime);
+
+        assertTrue(verifyFileName(fileName));
+    }
+
+    String getFileName(String currentTime) {
+        return MessageFormat.format("{0}.txt", currentTime);
+    }
+
+    boolean verifyFileName(String fileName) {
+        return Pattern
+            .compile("[0-9]{14}+\\.txt", Pattern.CASE_INSENSITIVE)
+            .matcher(fileName)
+            .matches();
+    }
+}

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

@@ -6,3 +6,4 @@
 - [Java 8 Predicate Chain](https://www.baeldung.com/java-predicate-chain)
 - [Use Cases for Static Methods in Java](https://www.baeldung.com/java-static-methods-use-cases)
 - [TriFunction Interface in Java](https://www.baeldung.com/java-trifunction)
+- [Lazy Field Initialization with Lambdas](https://www.baeldung.com/java-lambda-lazy-field-initialization)

core-java-modules/core-java-io-4/README.md

@@ -9,7 +9,7 @@ This module contains articles about core Java input and output (IO)
 - [SequenceInputStream Class in Java](https://www.baeldung.com/java-sequenceinputstream)
 - [Read a File Into a Map in Java](https://www.baeldung.com/java-read-file-into-map)
 - [Read User Input Until a Condition Is Met](https://www.baeldung.com/java-read-input-until-condition)
-- [Java Scanner.skip method with examples](https://www.baeldung.com/java-scanner-skip)
+- [Java Scanner.skip Method with Examples](https://www.baeldung.com/java-scanner-skip)
 - [Generate the MD5 Checksum for a File in Java](https://www.baeldung.com/java-md5-checksum-file)
 - [Getting the Filename From a String Containing an Absolute File Path](https://www.baeldung.com/java-filename-full-path)
 - [Mocking Java InputStream Object](https://www.baeldung.com/java-mocking-inputstream)

core-java-modules/core-java-io-5/README.md

@@ -6,5 +6,7 @@ This module contains articles about core Java input and output (IO)
 - [Get File Extension From MIME Type in Java](https://www.baeldung.com/java-mime-type-file-extension)
 - [How to Remove Line Breaks From a File in Java](https://www.baeldung.com/java-file-remove-line-breaks)
 - [Difference Between ZipFile and ZipInputStream in Java](https://www.baeldung.com/java-zipfile-vs-zipinputstream)
+- [How to Write Strings to OutputStream in Java](https://www.baeldung.com/java-write-string-outputstream)
+- [Read a File and Split It Into Multiple Files in Java](https://www.baeldung.com/java-read-file-split-into-several)
 - [[<-- Prev]](/core-java-modules/core-java-io-4)
 

core-java-modules/core-java-io-apis-2/README.md

@@ -9,3 +9,5 @@ This module contains articles about core Java input/output(IO) APIs.
 - [Converting Relative to Absolute Paths in Java](https://www.baeldung.com/java-from-relative-to-absolute-paths)
 - [Detect EOF in Java](https://www.baeldung.com/java-file-detect-end-of-file)
 - [PrintWriter vs. FileWriter in Java](https://www.baeldung.com/java-printwriter-filewriter-difference)
+- [Read Input Character-by-Character in Java](https://www.baeldung.com/java-read-input-character)
+- [Difference Between flush() and close() in Java FileWriter](https://www.baeldung.com/java-filewriter-flush-vs-close)

core-java-modules/core-java-io-apis/README.md

@@ -11,5 +11,5 @@ This module contains articles about core Java input/output(IO) APIs.
 - [Quick Use of FilenameFilter](https://www.baeldung.com/java-filename-filter)
 - [Guide to BufferedReader](https://www.baeldung.com/java-buffered-reader)
 - [Difference Between FileReader and BufferedReader in Java](https://www.baeldung.com/java-filereader-vs-bufferedreader)
-- [Java: Read Multiple Inputs on Same Line](https://www.baeldung.com/java-read-multiple-inputs-same-line)
+- [Read Multiple Inputs on the Same Line in Java](https://www.baeldung.com/java-read-multiple-inputs-same-line)
 - [Write Console Output to Text File in Java](https://www.baeldung.com/java-write-console-output-file)

core-java-modules/core-java-lang-6/Dockerfile

@@ -0,0 +1,7 @@
+FROM maven:3.9-amazoncorretto-17
+WORKDIR /app
+COPY /src/test/java/com/baeldung/setenvironment/SettingDockerEnvironmentVariableUnitTest.java \
+ ./src/test/java/com/baeldung/setenvironment/
+COPY /docker-pom.xml ./
+ENV CUSTOM_DOCKER_ENV_VARIABLE=TRUE
+ENTRYPOINT mvn -f docker-pom.xml test

core-java-modules/core-java-lang-6/README.md

@@ -10,4 +10,7 @@ This module contains articles about core features in the Java language
 - [Stop Executing Further Code in Java](https://www.baeldung.com/java-stop-running-code)
 - [Using the Apache Commons Lang 3 for Comparing Objects in Java](https://www.baeldung.com/java-apache-commons-lang-3-compare-objects)
 - [Return First Non-null Value in Java](https://www.baeldung.com/java-first-non-null)
+- [Compress and Uncompress Byte Array Using Deflater/Inflater](https://www.baeldung.com/java-compress-uncompress-byte-array)
 - [Static Final Variables in Java](https://www.baeldung.com/java-static-final-variables)
+- [What Is the Error: “Non-static method cannot be referenced from a static context”?](https://www.baeldung.com/java-non-static-method-cannot-be-referenced-from-a-static-context)
+- [Recursively Sum the Integers in an Array](https://www.baeldung.com/java-recursive-sum-integer-array)

core-java-modules/core-java-lang-6/docker-pom.xml

@@ -0,0 +1,42 @@
+<?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>
+
+    <groupId>com.baeldung.core-java-modules</groupId>
+    <artifactId>core-java-lang-6</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>testcontainers</artifactId>
+            <version>${testcontainers.junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${testcontainers.junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>5.10.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>5.10.1</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <testcontainers.junit.version>1.19.3</testcontainers.junit.version>
+    </properties>
+
+</project>

core-java-modules/core-java-lang-6/pom.xml

@@ -33,6 +33,25 @@
             <artifactId>jmh-generator-annprocess</artifactId>
             <version>${jmh.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.junit-pioneer</groupId>
+            <artifactId>junit-pioneer</artifactId>
+            <version>${junit.pioneer.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>testcontainers</artifactId>
+            <version>${testcontaienr.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${testcontaienr.version}</version>
+            <scope>test</scope>
+        </dependency>
+
     </dependencies>
     <build>
         <plugins>
@@ -53,6 +72,8 @@
                             <version>${jmh.version}</version>
                         </path>
                     </annotationProcessorPaths>
+                    <source>14</source>
+                    <target>14</target>
                 </configuration>
             </plugin>
         </plugins>
@@ -61,6 +82,8 @@
     <properties>
         <mapstruct.version>1.6.0.Beta1</mapstruct.version>
         <jmh.version>1.37</jmh.version>
+        <junit.pioneer.version>2.2.0</junit.pioneer.version>
+        <testcontaienr.version>1.19.3</testcontaienr.version>
     </properties>
 
 </project>

core-java-modules/core-java-lang-6/src/test/java/com/baeldung/setenvironment/SettingChildProcessEnvironmentVariableUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.setenvironment;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.IOException;
+import java.util.Map;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledIfEnvironmentVariable;
+
+class SettingChildProcessEnvironmentVariableUnitTest {
+
+    public static final String ENVIRONMENT_VARIABLE_NAME = "test";
+    public static final String ENVIRONMENT_VARIABLE_VALUE = "Hello World";
+    public static final String CHILD_PROCESS_CONDITION = "CHILD_PROCESS_TEST";
+    public static final String CHILD_PROCESS_VALUE = "true";
+    public static final String CHILD_PROCESS_TAG = "child_process";
+    public static final String TAG = String.format("-Dgroups=%s", CHILD_PROCESS_TAG);
+    private final String testClass = String.format("-Dtest=%s", getClass().getName());
+    private final String[] arguments = {"mvn", "test", TAG, testClass};
+
+    @Test
+    void givenChildProcessTestRunner_whenRunTheTest_thenAllSucceed()
+      throws IOException, InterruptedException {
+        ProcessBuilder processBuilder = new ProcessBuilder();
+        processBuilder.inheritIO();
+
+        Map<String, String> environment = processBuilder.environment();
+        environment.put(CHILD_PROCESS_CONDITION, CHILD_PROCESS_VALUE);
+        environment.put(ENVIRONMENT_VARIABLE_NAME, ENVIRONMENT_VARIABLE_VALUE);
+        Process process = processBuilder.command(arguments).start();
+
+        int errorCode = process.waitFor();
+        assertThat(errorCode).isZero();
+    }
+
+    @Test
+    @EnabledIfEnvironmentVariable(named = CHILD_PROCESS_CONDITION, matches = CHILD_PROCESS_VALUE)
+    @Tag(CHILD_PROCESS_TAG)
+    void givenChildProcess_whenGetEnvironmentVariable_thenReturnsCorrectValue() {
+        String actual = System.getenv(ENVIRONMENT_VARIABLE_NAME);
+        assertThat(actual).isEqualTo(ENVIRONMENT_VARIABLE_VALUE);
+    }
+}

core-java-modules/core-java-lang-6/src/test/java/com/baeldung/setenvironment/SettingDockerEnvironmentVariableUnitTest.java

@@ -0,0 +1,19 @@
+package com.baeldung.setenvironment;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledIfEnvironmentVariable;
+
+class SettingDockerEnvironmentVariableUnitTest {
+
+    public static final String ENV_VARIABLE_NAME = "CUSTOM_DOCKER_ENV_VARIABLE";
+    public static final String ENV_VARIABLE_VALUE = "TRUE";
+
+    @Test
+    @EnabledIfEnvironmentVariable(named = ENV_VARIABLE_NAME, matches = ENV_VARIABLE_VALUE)
+    void givenDockerEnvironment_whenGetEnvironmentVariable_thenReturnsCorrectValue() {
+        String actual = System.getenv(ENV_VARIABLE_NAME);
+        assertEquals(ENV_VARIABLE_VALUE, actual);
+    }
+}

core-java-modules/core-java-lang-6/src/test/java/com/baeldung/setenvironment/SettingSameProcessEnvironmentVariableUnitTest.java

@@ -0,0 +1,83 @@
+package com.baeldung.setenvironment;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.lang.reflect.Field;
+import java.util.Collections;
+import java.util.Map;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledForJreRange;
+import org.junit.jupiter.api.condition.EnabledIfEnvironmentVariable;
+import org.junit.jupiter.api.condition.JRE;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+import org.junitpioneer.jupiter.SetEnvironmentVariable;
+
+class SettingSameProcessEnvironmentVariableUnitTest {
+
+    private static final String PROCESS_ENVIRONMENT = "java.lang.ProcessEnvironment";
+    private static final String ENVIRONMENT = "theUnmodifiableEnvironment";
+    private static final String SOURCE_MAP = "m";
+    private static final Object STATIC_METHOD = null;
+    private static final Class<?> UMODIFIABLE_MAP_CLASS
+      = Collections.unmodifiableMap(Collections.emptyMap()).getClass();
+    private static final Class<?> MAP_CLASS = Map.class;
+    public static final String ENV_VARIABLE_NAME = "test";
+    public static final String ENV_VARIABLE_VALUE = "Hello World";
+
+    @ParameterizedTest
+    @CsvSource({ENV_VARIABLE_VALUE + "," + ENV_VARIABLE_NAME})
+    @EnabledForJreRange(max = JRE.JAVA_16)
+    void givenReflexiveAccess_whenGetSourceMap_thenSuccessfullyModifyVariables(String environmentVariable, String value)
+      throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException {
+        Map<String, String> modifiableEnvironment = getModifiableEnvironment();
+        assertThat(modifiableEnvironment).isNotNull();
+
+        modifiableEnvironment.put(environmentVariable, value);
+        String actual = modifiableEnvironment.get(environmentVariable);
+        assertThat(actual).isEqualTo(value);
+    }
+
+    @Test
+    @EnabledIfEnvironmentVariable(named = "PATH", matches = ".*",
+      disabledReason = "The test relies on the presence of PATH variable")
+    void givenOS_whenGetPath_thenVariableIsPresent() {
+        String classPath = System.getenv("PATH");
+        assertThat(classPath).isNotNull();
+    }
+
+    @Test
+    void givenOS_whenGetEnv_thenVariablesArePresent() {
+        Map<String, String> environment = System.getenv();
+        assertThat(environment).isNotNull();
+    }
+
+    @Test
+    @SetEnvironmentVariable(key = ENV_VARIABLE_NAME, value = ENV_VARIABLE_VALUE)
+    @EnabledForJreRange(max = JRE.JAVA_16)
+    void givenVariableSet_whenGetEnvironmentVariable_thenReturnsCorrectValue() {
+        String actual = System.getenv(ENV_VARIABLE_NAME);
+        assertThat(actual).isEqualTo(ENV_VARIABLE_VALUE);
+    }
+
+    @SuppressWarnings("unchecked")
+    private static Map<String, String> getModifiableEnvironment()
+      throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException {
+        Class<?> environmentClass = Class.forName(PROCESS_ENVIRONMENT);
+        Field environmentField = environmentClass.getDeclaredField(ENVIRONMENT);
+        assertThat(environmentField).isNotNull();
+        environmentField.setAccessible(true);
+
+        Object unmodifiableEnvironmentMap = environmentField.get(STATIC_METHOD);
+        assertThat(unmodifiableEnvironmentMap).isNotNull();
+        assertThat(unmodifiableEnvironmentMap).isInstanceOf(UMODIFIABLE_MAP_CLASS);
+
+        Field underlyingMapField = unmodifiableEnvironmentMap.getClass().getDeclaredField(SOURCE_MAP);
+        underlyingMapField.setAccessible(true);
+        Object underlyingMap = underlyingMapField.get(unmodifiableEnvironmentMap);
+        assertThat(underlyingMap).isNotNull();
+        assertThat(underlyingMap).isInstanceOf(MAP_CLASS);
+
+        return (Map<String, String>) underlyingMap;
+    }
+}

core-java-modules/core-java-lang-6/src/test/java/com/baeldung/setenvironment/SettingTestcontainerVariableUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.setenvironment;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.testcontainers.containers.GenericContainer;
+import org.testcontainers.images.builder.ImageFromDockerfile;
+
+class SettingTestcontainerVariableUnitTest {
+
+    public static final String CONTAINER_REPORT_FILE = "/app/target/surefire-reports/TEST-com.baeldung.setenvironment.SettingDockerEnvironmentVariableUnitTest.xml";
+    public static final String HOST_REPORT_FILE = "./container-test-report.xml";
+    public static final String DOCKERFILE = "./Dockerfile";
+
+    @Test
+    @Disabled("Requires working Docker environment ")
+    void givenTestcontainerEnvironment_whenGetEnvironmentVariable_thenReturnsCorrectValue() {
+        Path dockerfilePath = Paths.get(DOCKERFILE);
+        GenericContainer container = new GenericContainer(
+          new ImageFromDockerfile().withDockerfile(dockerfilePath));
+        assertThat(container).isNotNull();
+        container.start();
+        while (container.isRunning()) {
+            // Busy spin
+        }
+        container.copyFileFromContainer(CONTAINER_REPORT_FILE, HOST_REPORT_FILE);
+    }
+}

core-java-modules/core-java-lang-math-3/README.md

@@ -13,4 +13,5 @@
 - [Java Money and the Currency API](http://www.baeldung.com/java-money-and-currency)
 - [Clamp Function in Java](https://www.baeldung.com/java-clamp-function)
 - [Creating a Magic Square in Java](https://www.baeldung.com/java-magic-square)
+- [Check if a Point Is Between Two Points Drawn on a Straight Line in Java](https://www.baeldung.com/java-check-point-straight-line)
 - More articles: [[<-- Prev]](/core-java-modules/core-java-lang-math-2)

core-java-modules/core-java-lang-math-3/src/main/java/com/baeldung/math/rotatevertex/VertexRotation.java

@@ -0,0 +1,26 @@
+package com.baeldung.math.rotatevertex;
+
+import java.awt.geom.AffineTransform;
+import java.awt.geom.Point2D;
+
+public class VertexRotation {
+    public static Point2D.Double usingOriginAsRotationPoint(Point2D.Double vertex, Point2D.Double rotationPoint, double angle) {
+        double translatedToOriginX = vertex.x - rotationPoint.x;
+        double translatedToOriginY = vertex.y - rotationPoint.y;
+
+        double rotatedX = translatedToOriginX * Math.cos(angle) - translatedToOriginY * Math.sin(angle);
+        double rotatedY = translatedToOriginX * Math.sin(angle) + translatedToOriginY * Math.cos(angle);
+
+        double reverseTranslatedX = rotatedX + rotationPoint.x;
+        double reverseTranslatedY = rotatedY + rotationPoint.y;
+
+        return new Point2D.Double(reverseTranslatedX, reverseTranslatedY);
+    }
+
+    public static Point2D.Double usingAffineTransform(Point2D.Double vertex, Point2D.Double rotationPoint, double angle) {
+        AffineTransform affineTransform = AffineTransform.getRotateInstance(angle, rotationPoint.x, rotationPoint.y);
+        Point2D.Double rotatedVertex = new Point2D.Double();
+        affineTransform.transform(vertex, rotatedVertex);
+        return rotatedVertex;
+    }
+}

core-java-modules/core-java-lang-math-3/src/test/java/com/baeldung/com.baeldung.powerinsteadofmathpow/FindPowerInsteadOfUsingMathPowUnitTest.java

@@ -0,0 +1,57 @@
+package com.baeldung.powerinsteadofmathpow;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class FindPowerInsteadOfUsingMathPowUnitTest {
+    double result = 1;
+    double base = 2;
+    int exponent = 3;
+
+    @Test
+    public void givenBaseAndExponentNumbers_whenUtilizingIterativeApproach_thenReturnThePower() {
+
+        for (int i = 0; i < exponent; i++) {
+            result *= base;
+        }
+
+        assertEquals(8, result);
+    }
+
+    @Test
+    public void givenBaseAndExponentNumbers_whenUtilizingRecursionApproach_thenReturnThePower() {
+
+        result = calculatePowerRecursively(base, exponent);
+
+        assertEquals(8, result);
+    }
+
+    private double calculatePowerRecursively(double base, int exponent) {
+        if (exponent == 0) {
+            return 1;
+        } else {
+            return base * calculatePowerRecursively(base, exponent - 1);
+        }
+    }
+
+    @Test
+    public void givenBaseAndExponentNumbers_whenUtilizingFastApproach_thenReturnThePower() {
+        result = calculatePowerFast(base, exponent);
+
+        assertEquals(8, result);
+    }
+
+    private double calculatePowerFast(double base, int exponent) {
+        if (exponent == 0) {
+            return 1;
+        }
+
+        double halfPower = calculatePowerFast(base, exponent / 2);
+        if (exponent % 2 == 0) {
+            return halfPower * halfPower;
+        } else {
+            return base * halfPower * halfPower;
+        }
+    }
+}

core-java-modules/core-java-lang-math-3/src/test/java/com/baeldung/math/rotatevertex/VertexRotationUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.math.rotatevertex;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.awt.geom.Point2D;
+
+import org.junit.jupiter.api.Test;
+
+public class VertexRotationUnitTest {
+    @Test
+    void givenRotationPoint_whenUseOrigin_thenRotateVertex() {
+        Point2D.Double vertex = new Point2D.Double(2.0, 2.0);
+        Point2D.Double rotationPoint = new Point2D.Double(0.0, 1.0);
+        double angle = Math.toRadians(45.0);
+        Point2D.Double rotatedVertex = VertexRotation.usingOriginAsRotationPoint(vertex, rotationPoint, angle);
+
+        assertEquals(0.707, rotatedVertex.getX(), 0.001);
+        assertEquals(3.121, rotatedVertex.getY(), 0.001);
+    }
+
+    @Test
+    void givenRotationPoint_whenUseAffineTransform_thenRotateVertex() {
+        Point2D.Double vertex = new Point2D.Double(2.0, 2.0);
+        Point2D.Double rotationPoint = new Point2D.Double(0.0, 1.0);
+        double angle = Math.toRadians(45.0);
+        Point2D.Double rotatedVertex = VertexRotation.usingAffineTransform(vertex, rotationPoint, angle);
+
+        assertEquals(0.707, rotatedVertex.getX(), 0.001);
+        assertEquals(3.121, rotatedVertex.getY(), 0.001);
+    }
+}

core-java-modules/core-java-lang-oop-generics/README.md

@@ -10,3 +10,4 @@ This module contains articles about generics in Java
 - [Java Warning “unchecked conversion”](https://www.baeldung.com/java-unchecked-conversion)
 - [Java Warning “Unchecked Cast”](https://www.baeldung.com/java-warning-unchecked-cast)
 - [What Does the Holder<T> Class Do in Java?](https://www.baeldung.com/java-holder-class)
+- [Determine the Class of a Generic Type in Java](https://www.baeldung.com/java-generic-type-find-class-runtime)

core-java-modules/core-java-networking-4/urlnormalization/URLNormalizationUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.urlnormalization;
+
+import org.junit.jupiter.api.Test;
+import org.apache.commons.validator.routines.UrlValidator;
+
+import java.io.UnsupportedEncodingException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class URLNormalizationUnitTest {
+    String originalUrl = "https://www.example.com:8080/path/to/resource?param1=value1&param2=value2#fragment";
+    String expectedNormalizedUrl = "https://www.example.com:8080/path/to/resource";
+
+    @Test
+    public void givenOriginalUrl_whenUsingApacheCommonsValidator_thenValidatedAndMaybeManuallyNormalized() {
+        UrlValidator urlValidator = new UrlValidator();
+        if (urlValidator.isValid(originalUrl)) {
+            String normalizedUri = originalUrl.split("\\?")[0];
+            assertEquals(expectedNormalizedUrl, normalizedUri);
+        } else {
+            throw new IllegalArgumentException("Invalid URL: " + originalUrl);
+        }
+    }
+
+    @Test
+    public void givenOriginalUrl_whenUsingJavaURIClass_thenNormalizedUrl() throws URISyntaxException {
+        URI uri = new URI(originalUrl);
+        URI normalizedUri = new URI(uri.getScheme(), uri.getAuthority(), uri.getPath(), null, null);
+        String normalizedUrl = normalizedUri.toString();
+        assertEquals(expectedNormalizedUrl, normalizedUrl);
+    }
+
+    @Test
+    public void givenOriginalUrl_whenUsingRegularExpression_thenNormalizedUrl() throws URISyntaxException, UnsupportedEncodingException {
+        String regex = "^(https?://[^/]+/[^?#]+)";
+        Pattern pattern = Pattern.compile(regex);
+        Matcher matcher = pattern.matcher(originalUrl);
+
+        if (matcher.find()) {
+            String normalizedUrl = matcher.group(1);
+            assertEquals(expectedNormalizedUrl, normalizedUrl);
+        } else {
+            throw new IllegalArgumentException("Invalid URL: " + originalUrl);
+        }
+    }
+}

core-java-modules/core-java-numbers-7/README.md

@@ -1,2 +1,3 @@
 ## Relevant Articles
 - [Check if a double Is an Integer in Java](https://www.baeldung.com/java-check-double-integer)
+- [Print a Double Value Without Scientific Notation in Java](https://www.baeldung.com/java-print-double-number-no-scientific-notation)

core-java-modules/core-java-numbers-conversions/README.md

@@ -2,7 +2,9 @@
 - [Convert a Number to a Letter in Java](https://www.baeldung.com/java-convert-number-to-letter)
 - [Convert Long to BigDecimal in Java](https://www.baeldung.com/java-convert-long-bigdecimal)
 - [Convert int to Long in Java](https://www.baeldung.com/java-convert-int-long)
-- [How To Convert Double To Float In Java](https://www.baeldung.com/java-convert-double-float)
+- [How to Convert Double to Float in Java](https://www.baeldung.com/java-convert-double-float)
 - [Converting from float to BigDecimal in Java](https://www.baeldung.com/java-convert-float-bigdecimal)
 - [Convert Positive Integer to Negative and Vice Versa in Java](https://www.baeldung.com/java-negating-integer)
 - [Rounding Up a Number to Nearest Multiple of 5 in Java](https://www.baeldung.com/java-round-nearest-multiple-five)
+- [Convert byte to int Type in Java](https://www.baeldung.com/java-byte-to-int-conversion)
+- [Converting Integer to BigDecimal in Java](https://www.baeldung.com/java-integer-bigdecimal-conversion)

core-java-modules/core-java-numbers-conversions/src/main/java/com/baeldung/bytetoint/ByteToIntConversion.java

@@ -0,0 +1,25 @@
+package com.baeldung.bytetoint;
+
+public class ByteToIntConversion {
+    static int usingTypeCasting(byte b){
+        int i = b;
+        return i;
+    }
+
+    static int usingIntegerValueOf(byte b){
+        return Integer.valueOf(b);
+    }
+
+    static int usingByteIntValue(byte b){
+        Byte byteObj = new Byte(b);
+        return byteObj.intValue();
+    }
+
+    static int usingMathToIntExact(byte b){
+        return Math.toIntExact(b);
+    }
+
+    static int usingByteUnsignedInt(byte b){
+        return Byte.toUnsignedInt(b);
+    }
+}

core-java-modules/core-java-numbers-conversions/src/test/java/com/baeldung/bytetoint/ByteToIntConversionUnitTest.java

@@ -0,0 +1,45 @@
+package com.baeldung.bytetoint;
+
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+
+public class ByteToIntConversionUnitTest {
+    @Test
+    public void givenByte_whenUsingTypeCasting_thenConvertToInt() {
+        byte b = -51;
+        int result = ByteToIntConversion.usingTypeCasting(b);
+            assertEquals(-51, result);
+    }
+
+    @Test
+    void givenByte_whenUsingIntegerValueOf_thenConvertToInt() {
+        byte b = -51;
+        int result = ByteToIntConversion.usingIntegerValueOf(b);
+
+        assertEquals(-51, result);
+    }
+
+    @Test
+    void givenByte_whenUsingByteIntValue_thenConvertToInt() {
+        byte b = -51;
+        int result = ByteToIntConversion.usingByteIntValue(b);
+
+        assertEquals(-51, result);
+    }
+
+    @Test
+    void givenByte_whenUsingMathToIntExact_thenConvertToInt() {
+        byte b = -51;
+        int result = ByteToIntConversion.usingMathToIntExact(b);
+
+        assertEquals(-51, result);
+    }
+
+    @Test
+    void givenByte_whenUsingByteUnsignedInt_thenConvertToInt() {
+        byte b = -51;
+        int result = ByteToIntConversion.usingByteUnsignedInt(b);
+
+        assertEquals(205, result);
+    }
+}

core-java-modules/core-java-perf-2/src/test/java/com/baeldung/oom/OomCrashUnitTest.java

@@ -0,0 +1,52 @@
+package com.baeldung.oom;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+@Disabled
+class OomCrashUnitTest {
+
+    public static final Runnable MEMORY_LEAK = () -> {
+        List<byte[]> list = new ArrayList<>();
+        while (true) {
+            list.add(tenMegabytes());
+        }
+    };
+
+    @Test
+    void givenMemoryLeakCode_whenRunInsideThread_thenMainAppDoestFail() throws InterruptedException {
+        Thread memoryLeakThread = new Thread(MEMORY_LEAK);
+        memoryLeakThread.start();
+        memoryLeakThread.join();
+    }
+
+    @Test
+    void givenMemoryLeakCode_whenRunSeveralTimesInsideThread_thenMainAppDoestFail() throws InterruptedException {
+        for (int i = 0; i < 5; i++) {
+            Thread memoryLeakThread = new Thread(MEMORY_LEAK);
+            memoryLeakThread.start();
+            memoryLeakThread.join();
+        }
+    }
+
+    @Test
+    void givenBadExample_whenUseItInProductionCode_thenQuestionedByEmployerAndProbablyFired()
+      throws InterruptedException {
+        Thread npeThread = new Thread(() -> {
+            String nullString = null;
+            try {
+                nullString.isEmpty();
+            } catch (NullPointerException e) {
+                throw new OutOfMemoryError(e.getMessage());
+            }
+        });
+        npeThread.start();
+        npeThread.join();
+    }
+
+    private static byte[] tenMegabytes() {
+        return new byte[1024 * 1014 * 10];
+    }
+}

core-java-modules/core-java-regex-2/README.md

@@ -9,5 +9,5 @@
 - [Regular Expression: \z vs \Z Anchors in Java](https://www.baeldung.com/java-regular-expression-z-vs-z-anchors)
 - [Extract Text Between Square Brackets](https://www.baeldung.com/java-get-content-between-square-brackets)
 - [Get the Indexes of Regex Pattern Matches in Java](https://www.baeldung.com/java-indexes-regex-pattern-matches)
-- [Check if a String is Strictly Alphanumeric With Java](https://www.baeldung.com/java-check-string-contains-only-letters-numbers)
+- [Check if a String Is Strictly Alphanumeric With Java](https://www.baeldung.com/java-check-string-contains-only-letters-numbers)
 - More articles: [[<-- prev]](/core-java-modules/core-java-regex)

core-java-modules/core-java-regex-3/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- More articles: [[<-- prev]](/core-java-modules/core-java-regex-2)

core-java-modules/core-java-regex-3/pom.xml

@@ -0,0 +1,24 @@
+<?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-regex-3</artifactId>
+    <name>core-java-regex-3</name>
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.8.1</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+</project>

core-java-modules/core-java-regex-3/src/test/java/com/baeldung/passwordvalidation/PasswordValidationUsingRegexUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.passwordvalidation;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class PasswordValidationUsingRegexUnitTest {
+    String password = "Baeldung20@";
+
+    @Test
+    public void givenStringPassword_whenUsingDynamicPasswordValidationRules_thenCheckIfPasswordValid() {
+        boolean result = false;
+        try {
+            if (password != null) {
+                String MIN_LENGTH = "8";
+                String MAX_LENGTH = "20";
+                boolean SPECIAL_CHAR_NEEDED = false;
+
+                String ONE_DIGIT = "(?=.*[0-9])";
+                String LOWER_CASE = "(?=.*[a-z])";
+                String UPPER_CASE = "(?=.*[A-Z])";
+                String SPECIAL_CHAR = SPECIAL_CHAR_NEEDED ? "(?=.*[@#$%^&+=])" : "";
+                String NO_SPACE = "(?=\\S+$)";
+
+                String MIN_MAX_CHAR = ".{" + MIN_LENGTH + "," + MAX_LENGTH + "}";
+                String PATTERN = ONE_DIGIT + LOWER_CASE + UPPER_CASE + SPECIAL_CHAR + NO_SPACE + MIN_MAX_CHAR;
+
+                assertTrue(password.matches(PATTERN));
+            }
+
+        } catch (Exception ex) {
+            ex.printStackTrace();
+            fail("Exception occurred: " + ex.getMessage());
+        }
+    }
+
+    @Test
+    public void givenStringPassword_whenUsingRegulaExpressions_thenCheckIfPasswordValid() {
+
+
+        String regExpn =
+                "^(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%^&+=])(?=\\S+$).{8,20}$";
+
+        Pattern pattern = Pattern.compile(regExpn, Pattern.CASE_INSENSITIVE);
+        Matcher matcher = pattern.matcher(password);
+
+        assertTrue(matcher.matches());
+    }
+
+}

core-java-modules/core-java-security-4/README.md

@@ -6,4 +6,5 @@ This module contains articles about core Java Security
 - [Check if Certificate Is Self-Signed or CA-Signed With Java](https://www.baeldung.com/java-check-certificate-sign)
 - [Extract CN From X509 Certificate in Java](https://www.baeldung.com/java-extract-common-name-x509-certificate)
 - [Check Certificate Name and Alias in Keystore File](https://www.baeldung.com/java-keystore-check-certificate-name-alias)
+- [Using a Custom TrustStore in Java](https://www.baeldung.com/java-custom-truststore)
 - More articles: [[<-- prev]](/core-java-modules/core-java-security-3)

core-java-modules/core-java-security-4/src/main/java/com/baeldung/enablessldebug/SSLDebugLogger.java

@@ -0,0 +1,32 @@
+package com.baeldung.enablessldebug;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.URL;
+
+import javax.net.ssl.HttpsURLConnection;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class SSLDebugLogger {
+    private static final Logger logger = LoggerFactory.getLogger(SSLDebugLogger.class);
+
+    public static void enableSSLDebugUsingSystemProperties() {
+        System.setProperty("javax.net.debug", "ssl");
+    }
+
+    public static void makeHttpsRequest() throws Exception {
+        String url = "https://github.com/eugenp/tutorials";
+        URL httpsUrl = new URL(url);
+        HttpsURLConnection connection = (HttpsURLConnection) httpsUrl.openConnection();
+
+        try (BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()))) {
+            String line;
+            logger.info("Response from " + url + ":");
+            while ((line = reader.readLine()) != null) {
+                logger.info(line);
+            }
+        }
+    }
+}

core-java-modules/core-java-security-4/src/test/java/com/baeldung/enablessldebug/SSLDebugLoggerUnitTest.java

@@ -0,0 +1,49 @@
+package com.baeldung.enablessldebug;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.PrintStream;
+import java.util.logging.ConsoleHandler;
+import java.util.logging.Level;
+import java.util.logging.LogManager;
+import java.util.logging.Logger;
+
+import org.junit.jupiter.api.Test;
+
+public class SSLDebugLoggerUnitTest {
+    @Test
+     void givenSSLDebuggingEnabled_whenUsingSystemProperties_thenEnableSSLDebugLogging() throws Exception {
+        ByteArrayOutputStream outContent = new ByteArrayOutputStream();
+        System.setErr(new PrintStream(outContent));
+
+        SSLDebugLogger.enableSSLDebugUsingSystemProperties();
+        assertEquals("ssl", System.getProperty("javax.net.debug"));
+
+        SSLDebugLogger.makeHttpsRequest();
+        assertTrue(outContent.toString().contains("javax.net.ssl|DEBUG|"));
+        outContent.reset();
+
+        System.clearProperty("javax.net.debug");
+        assertNull(System.getProperty("javax.net.debug"));
+
+        SSLDebugLogger.makeHttpsRequest();
+        assertEquals(outContent.toString(),"");
+    }
+
+    @Test
+     void givenSSLDebuggingEnabled_whenUsingConfigurationFile_thenEnableSSLDebugLogging() throws IOException {
+        InputStream configFile = SSLDebugLoggerUnitTest.class.getClassLoader().getResourceAsStream("logging.properties");
+        LogManager.getLogManager().readConfiguration(configFile);
+
+        Logger sslLogger = Logger.getLogger("javax.net.ssl");
+        ConsoleHandler consoleHandler = (ConsoleHandler) sslLogger.getHandlers()[0];
+        Level consoleHandlerLevel = consoleHandler.getLevel();
+
+        assertEquals(Level.ALL, consoleHandlerLevel, "SSL ConsoleHandler level should be ALL");
+    }
+}

core-java-modules/core-java-security-4/src/test/resources/logging.properties

@@ -0,0 +1,3 @@
+java.util.logging.ConsoleHandler.level=ALL
+javax.net.ssl.handlers=java.util.logging.ConsoleHandler
+javax.net.ssl.level=ALL

core-java-modules/core-java-string-algorithms-4/README.md

@@ -4,3 +4,4 @@ This module contains articles about string-related algorithms.
 
 ### Relevant Articles:
 - [Rotating a Java String By n Characters](https://www.baeldung.com/java-rotate-string-by-n-characters)
+- [Remove Characters From a String That Are in the Other String](https://www.baeldung.com/java-strings-character-difference)

core-java-modules/core-java-string-conversions-3/README.md

@@ -5,4 +5,4 @@
 - [Split Java String Into Key-Value Pairs](https://www.baeldung.com/java-split-string-map)
 - [How to Center Text Output in Java](https://www.baeldung.com/java-center-text-output)
 - [How to Convert an Object to String](https://www.baeldung.com/java-object-string-representation)
-- [Convert String to long or Long in Java](https://www.baeldung.com/java-convert-string-to-long)
+- [Convert String to long or Long in Java](https://www.baeldung.com/java-convert-string-long)

core-java-modules/core-java-string-operations-7/README.md

@@ -3,7 +3,12 @@
 - [How to Center Text Output in Java](https://www.baeldung.com/java-center-text-output)
 - [Capitalize the First Letter of Each Word in a String](https://www.baeldung.com/java-string-initial-capital-letter-every-word)
 - [Check if a String Contains Only Unicode Letters](https://www.baeldung.com/java-string-all-unicode-characters)
-- [Create a Mutable String in Java](https://www.baeldung.com/java-mutable-string)
+- [Create a “Mutable” String in Java](https://www.baeldung.com/java-mutable-string)
 - [Check if a String Contains a Number Value in Java](https://www.baeldung.com/java-string-number-presence)
 - [Difference Between String isEmpty() and isBlank()](https://www.baeldung.com/java-string-isempty-vs-isblank)
 - [String’s Maximum Length in Java](https://www.baeldung.com/java-strings-maximum-length)
+- [Java’s String.length() and String.getBytes().length](https://www.baeldung.com/java-string-length-vs-getbytes-length)
+- [Replace Non-Printable Unicode Characters in Java](https://www.baeldung.com/java-replace-non-printable-unicode-characters)
+- [Check If a Java StringBuilder Object Contains a Character](https://www.baeldung.com/java-check-stringbuilder-object-contains-character)
+- [Comparing One String With Multiple Values in One Expression in Java](https://www.baeldung.com/java-compare-string-multiple-values-one-expression)
+- [UTF-8 Validation in Java](https://www.baeldung.com/java-utf-8-validation)

core-java-modules/core-java-string-operations-7/pom.xml

@@ -39,6 +39,11 @@
             <artifactId>icu4j</artifactId>
             <version>${icu4j.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${apache.commons.collection.version}</version>
+        </dependency>        
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter</artifactId>
@@ -75,6 +80,7 @@
         <maven.compiler.source>11</maven.compiler.source>
         <maven.compiler.target>11</maven.compiler.target>
         <apache.commons.lang3.version>3.13.0</apache.commons.lang3.version>
+        <apache.commons.collection.version>4.4</apache.commons.collection.version>        
         <apache.tika.version>2.9.1</apache.tika.version>
         <commons-text.version>1.10.0</commons-text.version>
         <icu4j.version>74.1</icu4j.version>

core-java-modules/core-java-string-operations-7/src/main/java/com/baeldung/morse/MorseTranslator.java

@@ -0,0 +1,103 @@
+package com.baeldung.morse;
+
+import org.apache.commons.collections4.BidiMap;
+import org.apache.commons.collections4.bidimap.DualHashBidiMap;
+
+public class MorseTranslator {
+
+    private static final BidiMap<String, String> morseAlphabet = new DualHashBidiMap<>();
+
+    static {
+        morseAlphabet.put("A", ".-");
+        morseAlphabet.put("B", "-...");
+        morseAlphabet.put("C", "-.-.");
+        morseAlphabet.put("D", "-..");
+        morseAlphabet.put("E", ".");
+        morseAlphabet.put("F", "..-.");
+        morseAlphabet.put("G", "--.");
+        morseAlphabet.put("H", "....");
+        morseAlphabet.put("I", "..");
+        morseAlphabet.put("J", ".---");
+        morseAlphabet.put("K", "-.-");
+        morseAlphabet.put("L", ".-..");
+        morseAlphabet.put("M", "--");
+        morseAlphabet.put("N", "-.");
+        morseAlphabet.put("O", "---");
+        morseAlphabet.put("P", ".--.");
+        morseAlphabet.put("Q", "--.-");
+        morseAlphabet.put("R", ".-.");
+        morseAlphabet.put("S", "...");
+        morseAlphabet.put("T", "-");
+        morseAlphabet.put("U", "..-");
+        morseAlphabet.put("V", "...-");
+        morseAlphabet.put("W", ".--");
+        morseAlphabet.put("X", "-..-");
+        morseAlphabet.put("Y", "-.--");
+        morseAlphabet.put("Z", "--..");
+        morseAlphabet.put("0", "-----");
+        morseAlphabet.put("1", ".----");
+        morseAlphabet.put("2", "..---");
+        morseAlphabet.put("3", "...--");
+        morseAlphabet.put("4", "....-");
+        morseAlphabet.put("5", ".....");
+        morseAlphabet.put("6", "-....");
+        morseAlphabet.put("7", "--...");
+        morseAlphabet.put("8", "---..");
+        morseAlphabet.put("9", "----.");
+        morseAlphabet.put(".", ".-.-.-");
+        morseAlphabet.put(",", "--..--");
+        morseAlphabet.put("?", "..--..");
+        morseAlphabet.put("'", ".----.");
+        morseAlphabet.put("!", "-.-.-----.");
+        morseAlphabet.put("/", "-..-.");
+        morseAlphabet.put("(", "-.--.");
+        morseAlphabet.put(")", "-.--.-");
+        morseAlphabet.put("&", ".-...");
+        morseAlphabet.put(":", "---...");
+        morseAlphabet.put(";", "-.-.-.");
+        morseAlphabet.put("=", "-...-");
+        morseAlphabet.put("+", ".-.-.");
+        morseAlphabet.put("-", "-....-");
+        morseAlphabet.put("_", "..--.-");
+        morseAlphabet.put("\"", ".-..-.");
+        morseAlphabet.put("$", "...-..-");
+        morseAlphabet.put("@", ".--.-.");
+        morseAlphabet.put(" ", "/");
+    }
+
+    static String englishToMorse(String english) {
+        if (english == null) {
+            return null;
+        }
+        String upperCaseEnglish = english.toUpperCase();
+        String[] morse = new String[upperCaseEnglish.length()];
+        for (int index = 0; index < upperCaseEnglish.length(); index++) {
+            String morseCharacter = morseAlphabet.get(String.valueOf(upperCaseEnglish.charAt(index)));
+            if (morseCharacter == null) {
+                throw new IllegalArgumentException("Character " + upperCaseEnglish.charAt(index) + " can't be translated to morse");
+            }
+            morse[index] = morseCharacter;
+        }
+        return String.join(" ", morse);
+    }
+
+    static String morseToEnglish(String morse) {
+        if (morse == null) {
+            return null;
+        }
+        if (morse.isEmpty()) {
+            return "";
+        }
+        String[] morseUnitCharacters = morse.split(" ");
+        StringBuilder stringBuilder = new StringBuilder();
+        for (int index = 0; index < morseUnitCharacters.length; index ++) {
+            String englishCharacter = morseAlphabet.getKey(morseUnitCharacters[index]);
+            if (englishCharacter == null) {
+                throw new IllegalArgumentException("Character " + morseUnitCharacters[index] + " is not a valid morse character");
+            }
+            stringBuilder.append(englishCharacter);
+        }
+        return stringBuilder.toString();
+    }
+
+}

core-java-modules/core-java-string-operations-7/src/test/java/com/baeldung/checkifstringcontainsinvalidcharacters/CheckIfStringContainsInvalidEncodedCharactersUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.checkifstringcontainsinvalidcharacters;
+
+import org.junit.jupiter.api.Test;
+
+import java.nio.charset.*;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class CheckIfStringContainsInvalidEncodedCharactersUnitTest {
+
+    public String input = "HÆllo, World!";
+
+    @Test
+    public void givenInputString_whenUsingRegexPattern_thenFindIfInvalidCharacters() {
+        String regexPattern = "[^\\x00-\\x7F]+";
+        Pattern pattern = Pattern.compile(regexPattern);
+        Matcher matcher = pattern.matcher(input);
+        assertTrue(matcher.find());
+    }
+
+    @Test
+    public void givenInputString_whenUsingStringEncoding_thenFindIfInvalidCharacters() {
+        byte[] bytes = input.getBytes(StandardCharsets.UTF_8);
+        boolean found = false;
+        for (byte b : bytes) {
+            found = (b & 0xFF) > 127 ? true : found;
+        }
+        assertTrue(found);
+    }
+}

core-java-modules/core-java-string-operations-7/src/test/java/com/baeldung/morse/MorseTranslatorUnitTest.java

@@ -0,0 +1,55 @@
+package com.baeldung.morse;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+public class MorseTranslatorUnitTest {
+
+    @ParameterizedTest
+    @ValueSource(strings = {"MORSE CODE!", "morse code!", "mOrSe cOdE!"})
+    void givenAValidEnglishWordWhateverTheCapitalization_whenEnglishToMorse_thenTranslatedToMorse(String english) {
+        assertEquals("-- --- .-. ... . / -.-. --- -.. . -.-.-----.", MorseTranslator.englishToMorse(english));
+    }
+
+    @Test
+    void givenAnEnglishWordWithAnIllegalCharacter_whenEnglishToMorse_thenThrows() {
+        String english = "~This sentence starts with an illegal character";
+        assertThrows(IllegalArgumentException.class, () -> MorseTranslator.englishToMorse(english));
+    }
+
+    @Test
+    void givenNull_whenEnglishToMorse_thenNull() {
+        assertNull(MorseTranslator.englishToMorse(null));
+    }
+
+    @Test
+    void givenEmptyString_whenEnglishToMorse_thenEmptyArray() {
+        assertEquals("", MorseTranslator.englishToMorse(""));
+    }
+
+    @Test
+    void givenAValidMorseWord_whenMorseToEnglish_thenTranslatedToUpperCaseEnglish() {
+        assertEquals("MORSE CODE!", MorseTranslator.morseToEnglish("-- --- .-. ... . / -.-. --- -.. . -.-.-----."));
+    }
+
+    @Test
+    void givenAMorseWordWithAnIllegalCharacter_whenMorseToEnglish_thenThrows() {
+        assertThrows(IllegalArgumentException.class, () -> MorseTranslator.morseToEnglish(".!!!!!!!"));
+    }
+
+    @Test
+    void givenNull_whenMorseToEnglish_thenNull() {
+        assertNull(MorseTranslator.morseToEnglish(null));
+    }
+
+    @Test
+    void givenEmptyArray_whenMorseToEnglish_thenEmptyString() {
+        assertEquals("", MorseTranslator.morseToEnglish(""));
+    }
+
+}

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

@@ -8,3 +8,4 @@ This module contains articles about the sun package
 - [Guide to sun.misc.Unsafe](http://www.baeldung.com/java-unsafe)
 - [Why Is sun.misc.Unsafe.park Actually Unsafe?](https://www.baeldung.com/java-sun-misc-unsafe-park-reason)
 - [Sharing Memory Between JVMs](https://www.baeldung.com/java-sharing-memory-between-jvms)
+- [Parse Java Source Code and Extract Methods](https://www.baeldung.com/java-parse-code-extract-methods)

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

@@ -3,8 +3,8 @@
          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-string-swing</artifactId>
-    <name>core-java-string-swing</name>
+    <artifactId>core-java-swing</artifactId>
+    <name>core-java-swing</name>
     <packaging>jar</packaging>
 
     <parent>

core-java-modules/core-java-time-measurements/README.md

@@ -7,3 +7,4 @@ This module contains articles about the measurement of time in Java.
 - [Measure Elapsed Time in Java](http://www.baeldung.com/java-measure-elapsed-time)
 - [Overriding System Time for Testing in Java](https://www.baeldung.com/java-override-system-time)
 - [Java Timer](http://www.baeldung.com/java-timer-and-timertask)
+- [Java System.currentTimeMillis() Vs. System.nanoTime()](https://www.baeldung.com/java-system-currenttimemillis-vs-system-nanotime)

core-java-modules/pom.xml

@@ -112,6 +112,7 @@
         <module>core-java-datetime-string-2</module>
         <module>core-java-date-operations-2</module>
         <module>core-java-date-operations-3</module>
+        <module>core-java-date-operations-4</module>
         <module>core-java-documentation</module>
         <module>core-java-exceptions</module>
         <module>core-java-exceptions-2</module>
@@ -199,6 +200,7 @@
         <module>core-java-string-operations-7</module>
         <module>core-java-regex</module>
         <module>core-java-regex-2</module>
+        <module>core-java-regex-3</module>
         <module>core-java-uuid</module>
         <module>core-java-collections-maps-6</module>
         <module>core-java-records</module>
@@ -209,6 +211,7 @@
         <module>core-java-collections-set</module>
         <module>core-java-date-operations-1</module>
         <module>core-java-datetime-conversion</module>
+        <module>core-java-datetime-conversion-2</module>
         <module>core-java-httpclient</module>
         <module>java-native</module>
         <module>java-rmi</module>

docker-modules/docker-caching/multi-module-caching/pom.xml

@@ -25,7 +25,7 @@
     </dependencyManagement>
 
     <properties>
-        <guava.version>32.1.3-jre</guava.version>
+        <guava.version>33.0.0-jre</guava.version>
     </properties>
 
 </project>

docker-modules/docker-caching/single-module-caching/pom.xml

@@ -49,7 +49,7 @@
         <maven.compiler.source>8</maven.compiler.source>
         <maven.compiler.target>8</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <guava.version>32.1.3-jre</guava.version>
+        <guava.version>33.0.0-jre</guava.version>
     </properties>
 
 </project>

gradle-modules/gradle-5/cmd-line-args/build.gradle

@@ -7,6 +7,8 @@ ext.javaMainClass = "com.baeldung.cmd.MainClass"
 application {
     mainClassName = javaMainClass
 }
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 task propertyTypes(){
     doLast{

gradle-modules/gradle-5/gradle-lint-intro/build.gradle

@@ -5,6 +5,9 @@ ext {
     awsVersion = '2.20.83'
 }
 
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
+
 
 dependencies {
     implementation platform("software.amazon.awssdk:bom:$awsVersion")

gradle-modules/gradle-5/java-exec/build.gradle

@@ -13,6 +13,8 @@ jar {
         )
     }
 }
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 application {
     mainClassName = javaMainClass

gradle-modules/gradle-5/source-sets/build.gradle

@@ -3,6 +3,9 @@ apply plugin: "eclipse"
 apply plugin: "java"
 
 description = "Source Sets example"
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
+
 
 task printSourceSetInformation(){
     description = "Print source set information"

gradle-modules/gradle-5/unused-dependencies/build.gradle

@@ -1,6 +1,9 @@
 
 description = "Gradle Unused Dependencies example"
 
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
+
 dependencies {
     implementation('com.google.guava:guava:29.0-jre')
     implementation('org.apache.httpcomponents:httpclient:4.5.12')

gradle-modules/gradle-6/dependency-constraints/build.gradle.kts

@@ -4,6 +4,8 @@ plugins {
 
 group = "com.baeldung"
 version = "1.0.0"
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 dependencies {
     api("io.reactivex.rxjava2:rxjava:2.2.16")

gradle-modules/gradle-6/fibonacci-recursive/build.gradle.kts

@@ -2,6 +2,9 @@ plugins {
     `java-library`
 }
 
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
+
 dependencies {
     api(project(":fibonacci-spi"))
     compileOnly("com.google.auto.service:auto-service-annotations:1.0-rc6")

gradle-modules/gradle-6/fibonacci-spi/build.gradle.kts

@@ -3,6 +3,9 @@ plugins {
     `java-test-fixtures`
 }
 
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
+
 dependencies {
     testFixturesApi("org.junit.jupiter:junit-jupiter-api:5.5.2")
     testFixturesImplementation("org.junit.jupiter:junit-jupiter-engine:5.5.2")

gradle-modules/gradle-6/httpclient-platform/build.gradle.kts

@@ -2,6 +2,9 @@ plugins {
     `java-platform`
 }
 
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
+
 dependencies {
     constraints {
         api("org.apache.httpcomponents:fluent-hc:4.5.10")

gradle-modules/gradle-6/module-metadata-publishing/build.gradle.kts

@@ -3,6 +3,9 @@ plugins {
     `maven-publish`
 }
 
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
+
 publishing {
     publications {
         register<MavenPublication>("mavenJava") {

gradle-modules/gradle-6/person-rest-client/build.gradle.kts

@@ -2,6 +2,9 @@ plugins {
     `java-library`
 }
 
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
+
 dependencies {
     api(platform(project(":httpclient-platform")))
     implementation("org.apache.httpcomponents:fluent-hc")

gradle-modules/gradle-6/widget-rest-client/build.gradle.kts

@@ -2,6 +2,9 @@ plugins {
     `java-library`
 }
 
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
+
 dependencies {
     api(platform(project(":httpclient-platform")))
     implementation("org.apache.httpcomponents:httpclient")

gradle-modules/gradle-7/conditional-dependency-demo/build.gradle.kts

@@ -6,6 +6,8 @@ plugins {
 
 group = "com.baeldung.gradle"
 version = "0.0.1-SNAPSHOT"
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 repositories {
 	mavenCentral()

gradle-modules/gradle-7/conditional-dependency-demo/consumer1/build.gradle.kts

@@ -4,6 +4,8 @@ plugins {
 
 group = "com.baeldung.gradle"
 version = "0.0.1-SNAPSHOT"
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 repositories {
     mavenCentral()

gradle-modules/gradle-7/conditional-dependency-demo/consumer2/build.gradle.kts

@@ -4,6 +4,8 @@ plugins {
 
 group = "com.baeldung.gradle"
 version = "0.0.1-SNAPSHOT"
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 repositories {
     mavenCentral()

gradle-modules/gradle-7/conditional-dependency-demo/provider1/build.gradle.kts

@@ -4,6 +4,8 @@ plugins {
 
 group = "com.baeldung.gradle"
 version = "0.0.1-SNAPSHOT"
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 repositories {
     mavenCentral()

gradle-modules/gradle-7/conditional-dependency-demo/provider2/build.gradle.kts

@@ -4,6 +4,8 @@ plugins {
 
 group = "com.baeldung.gradle"
 version = "0.0.1-SNAPSHOT"
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 repositories {
     mavenCentral()

gradle-modules/gradle-7/gradle-javadoc/build.gradle

@@ -4,6 +4,8 @@ plugins {
 
 group 'org.example'
 version '1.0-SNAPSHOT'
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 javadoc {
     destinationDir = file("${buildDir}/docs/javadoc")

gradle-modules/gradle-7/gradle-proxy-configuration/build.gradle

@@ -4,6 +4,8 @@ plugins {
 
 group = 'org.baeldung'
 version = '1.0-SNAPSHOT'
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 repositories {
     mavenCentral()

gradle-modules/gradle-7/gradle-wsdl-stubs/build.gradle

@@ -3,6 +3,9 @@ plugins {
     id 'com.github.bjornvester.wsdl2java' version '2.0.2'
 }
 
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
+
 repositories {
     mavenCentral()
 }

gradle-modules/gradle-7/multiple-repositories-demo/publish-package/build.gradle

@@ -5,6 +5,8 @@ plugins {
 
 group = "com.baeldung.gradle"
 version = "1.0.0-SNAPSHOT"
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 repositories {
     mavenLocal()

gradle-modules/gradle/gradle-employee-app/build.gradle

@@ -6,8 +6,8 @@ plugins {
 apply plugin: 'application'
 mainClassName = 'employee.EmployeeApp'
 
-sourceCompatibility = JavaVersion.VERSION_1_8
-targetCompatibility = JavaVersion.VERSION_1_8
+sourceCompatibility = "1.8"
+targetCompatibility = "1.8"
 
 println 'This is executed during configuration phase'
 

gradle-modules/gradle/gradle-fat-jar/build.gradle

@@ -13,6 +13,9 @@ plugins {
   id 'java'
 }
 
+sourceCompatibility = JavaVersion.VERSION_1_8
+targetCompatibility = JavaVersion.VERSION_1_8
+
 repositories {
     mavenCentral()
 }

gradle-modules/gradle/gradle-to-maven/build.gradle

@@ -10,6 +10,8 @@ group = 'com.baeldung'
 // by default, pom's artifactId is taken from the directory name
 
 version = '0.0.1'
+sourceCompatibility = JavaVersion.VERSION_1_8
+targetCompatibility = JavaVersion.VERSION_1_8
 
 dependencies {
     implementation 'org.slf4j:slf4j-api:1.7.25'

gradle-modules/gradle/gradletaskdemo/build.gradle

@@ -13,6 +13,9 @@ plugins {
     id 'java'
 }
 
+sourceCompatibility = JavaVersion.VERSION_1_8
+targetCompatibility = JavaVersion.VERSION_1_8
+
 apply from: 'aplugin.gradle'
 apply plugin: 'org.shipkit.bintray-release'