Merge branch 'eugenp:master' into master

2024-01-28 10:08:35 +01:00
parent 489e932e38 002384b668
commit b62cf9c77c
458 changed files with 11453 additions and 691 deletions
@@ -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)
@@ -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;
+        }
+    }
+}
@@ -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)
@@ -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>
@@ -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);
+        }
+    }
+}
@@ -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);
+        }
+    }
+}
@@ -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");
+        }
+    }
+}
@@ -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)
@@ -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;
+    }
+}
@@ -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));
+    }
+}
@@ -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"));
+    }
+}
@@ -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"));
+    }
+}
@@ -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)
@@ -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)
@@ -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());
+    }
+
+}
@@ -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)
@@ -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)
@@ -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)
@@ -0,0 +1,5 @@
+## Core Date Operations (Part 4)
+This module contains articles about date operations in Java.
+
+### Relevant Articles:
+
@@ -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>
@@ -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;
+    }
+
+
+}
@@ -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);
+    }
+
+}
@@ -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);
+    }
+
+}
@@ -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: 
+
@@ -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>
@@ -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;
+    }
+}
@@ -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));
+    }
+}
@@ -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)
@@ -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>
@@ -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();
+    }
+}
--- a/Show More
+++ b/Show More