Merge branch 'master' of https://github.com/eugenp/tutorials into BAEL-7487-resolve-multiple-completable-futures

core-java-modules/core-java-11-3/pom.xml

@@ -46,7 +46,7 @@
         <maven.compiler.source.version>11</maven.compiler.source.version>
         <maven.compiler.target.version>11</maven.compiler.target.version>
         <jackson.version>2.16.0</jackson.version>
-        <gson.version>2.10</gson.version>
+        <gson.version>2.10.1</gson.version>
     </properties>
 
 </project>

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

@@ -3,3 +3,4 @@
 - [String Templates in Java 21](https://www.baeldung.com/java-21-string-templates)
 - [Unnamed Classes and Instance Main Methods in Java 21](https://www.baeldung.com/java-21-unnamed-class-instance-main)
 - [Unnamed Patterns and Variables in Java 21](https://www.baeldung.com/java-unnamed-patterns-variables)
+- [JFR View Command in Java 21](https://www.baeldung.com/java-flight-recorder-view)

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 +9,8 @@
 - [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)
+- [Check if Two Date Ranges Overlap](https://www.baeldung.com/java-check-two-date-ranges-overlap)
+- [Difference between ZoneOffset.UTC and ZoneId.of(“UTC”)](https://www.baeldung.com/java-zoneoffset-utc-zoneid-of)
 - [[<-- 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-arrays-convert/README.md

@@ -12,3 +12,4 @@ This module contains articles about arrays conversion in Java
 - [Convert an ArrayList of String to a String Array in Java](https://www.baeldung.com/java-convert-string-arraylist-array)
 - [Convert Char Array to Int Array in Java](https://www.baeldung.com/java-convert-char-int-array)
 - [How to Convert Byte Array to Char Array](https://www.baeldung.com/java-convert-byte-array-char)
+- [Convert byte[] to Byte[] and Vice Versa in Java](https://www.baeldung.com/java-byte-array-wrapper-primitive-type-convert)

core-java-modules/core-java-arrays-convert/src/test/java/com/baeldung/array/conversions/ByteArrayToPrimitiveByteArrayUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.array.conversions;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.apache.commons.lang3.ArrayUtils;
+import org.junit.jupiter.api.Test;
+
+public class ByteArrayToPrimitiveByteArrayUnitTest {
+    private static final byte[] EXPECTED_ARRAY_VALUES = {65, 66, 67, 68};
+    private static final Byte[] BYTE_ARRAY = {65, 66, 67, 68};
+
+    @Test
+    public void givenByteArray_whenConvertingUsingByteValue_thenGiveExpectedResult() {
+        byte[] newByteArray = new byte[BYTE_ARRAY.length];
+        for (int i = 0; i < BYTE_ARRAY.length; i++) {
+            newByteArray[i] = BYTE_ARRAY[i].byteValue();
+        }
+        assertThat(newByteArray).containsExactly(EXPECTED_ARRAY_VALUES);
+    }
+
+    @Test
+    public void givenByteArray_whenConvertingUsingUnboxing_thenGiveExpectedResult() {
+        byte[] newByteArray = new byte[BYTE_ARRAY.length];
+        for (int i = 0; i < BYTE_ARRAY.length; i++) {
+            newByteArray[i] = BYTE_ARRAY[i];
+        }
+        assertThat(newByteArray).containsExactly(EXPECTED_ARRAY_VALUES);
+    }
+
+    @Test
+    public void givenByteArray_whenConvertingArrayUtils_thenGiveExpectedResult() {
+        byte[] newByteArray = ArrayUtils.toPrimitive(BYTE_ARRAY);
+
+        assertThat(newByteArray).containsExactly(EXPECTED_ARRAY_VALUES);
+    }
+}

core-java-modules/core-java-arrays-convert/src/test/java/com/baeldung/array/conversions/PrimitiveByteArrayToByteArrayUnitTest.java

@@ -0,0 +1,47 @@
+package com.baeldung.array.conversions;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Arrays;
+
+import org.apache.commons.lang3.ArrayUtils;
+import org.junit.jupiter.api.Test;
+
+public class PrimitiveByteArrayToByteArrayUnitTest {
+    private static final byte[] PRIMITIVE_BYTE_ARRAY = {65, 66, 67, 68};
+    private static final Byte[] EXPECTED_ARRAY_VALUES = {65, 66, 67, 68};
+
+    @Test
+    public void givenPrimitiveByteArray_whenConvertingUsingByteValueOf_thenGiveExpectedResult() {
+        Byte[] newByteArray = new Byte[PRIMITIVE_BYTE_ARRAY.length];
+        for (int i = 0; i < PRIMITIVE_BYTE_ARRAY.length; i++) {
+            newByteArray[i] = Byte.valueOf(PRIMITIVE_BYTE_ARRAY[i]);
+        }
+        assertThat(newByteArray).containsExactly(EXPECTED_ARRAY_VALUES);
+    }
+
+    @Test
+    public void givenPrimitiveByteArray_whenConvertingUsingAutoboxing_thenGiveExpectedResult() {
+        Byte[] newByteArray = new Byte[PRIMITIVE_BYTE_ARRAY.length];
+        for (int i = 0; i < PRIMITIVE_BYTE_ARRAY.length; i++) {
+            newByteArray[i] = PRIMITIVE_BYTE_ARRAY[i];
+        }
+        assertThat(newByteArray).containsExactly(EXPECTED_ARRAY_VALUES);
+    }
+
+    @Test
+    public void givenPrimitiveByteArray_whenConvertingUsingAutoboxingAndArraysSetAll_thenGiveExpectedResult() {
+        Byte[] newByteArray = new Byte[PRIMITIVE_BYTE_ARRAY.length];
+        Arrays.setAll(newByteArray, n -> PRIMITIVE_BYTE_ARRAY[n]);
+
+        assertThat(newByteArray)
+            .containsExactly(EXPECTED_ARRAY_VALUES);
+    }
+
+    @Test
+    public void givenPrimitiveByteArray_whenConvertingUsingArrayUtils_thenGiveExpectedResult() {
+        Byte[] newByteArray = ArrayUtils.toObject(PRIMITIVE_BYTE_ARRAY);
+
+        assertThat(newByteArray).containsExactly(EXPECTED_ARRAY_VALUES);
+    }
+}

core-java-modules/core-java-arrays-guides/README.md

@@ -10,3 +10,4 @@ This module contains complete guides about arrays in Java
 - [Creating a Generic Array in Java](https://www.baeldung.com/java-generic-array)
 - [Maximum Size of Java Arrays](https://www.baeldung.com/java-arrays-max-size)
 - [Merge Two Arrays and Remove Duplicates in Java](https://www.baeldung.com/java-merge-two-arrays-delete-duplicates)
+- [Print a Java 2D Array](https://www.baeldung.com/java-2d-array-print)

core-java-modules/core-java-arrays-guides/pom.xml

@@ -7,10 +7,6 @@
     <name>core-java-arrays-guides</name>
     <packaging>jar</packaging>
 
-    <properties>
-        <system-stubs.jupiter.version>2.1.5</system-stubs.jupiter.version>
-    </properties>
-
     <parent>
         <artifactId>core-java-modules</artifactId>
         <groupId>com.baeldung.core-java-modules</groupId>
@@ -34,7 +30,10 @@
             <version>${system-stubs.jupiter.version}</version>
             <scope>test</scope>
         </dependency>
-
     </dependencies>
 
+    <properties>
+        <system-stubs.jupiter.version>2.1.5</system-stubs.jupiter.version>
+    </properties>
+
 </project>

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

@@ -6,3 +6,4 @@ This module contains articles about Java Character Class
 - [Character#isAlphabetic vs. Character#isLetter](https://www.baeldung.com/java-character-isletter-isalphabetic)
 - [Difference Between Java’s “char” and “String”](https://www.baeldung.com/java-char-vs-string)
 - [Increment Character in Java](https://www.baeldung.com/java-char-sequence)
+- [Creating Unicode Character From Its Code Point Hex String](https://www.baeldung.com/java-unicode-character-from-code-point-hex-string)

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 +11,7 @@
 - [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)
+- [PriorityQueue iterator() Method in Java](https://www.baeldung.com/java-priorityqueue-iterator)
 - More articles: [[<-- prev]](/core-java-modules/core-java-collections-4)

core-java-modules/core-java-collections-5/pom.xml

@@ -5,18 +5,6 @@
     <modelVersion>4.0.0</modelVersion>
     <artifactId>core-java-collections-5</artifactId>
     <name>core-java-collections-5</name>
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
-                <configuration>
-                    <source>9</source>
-                    <target>9</target>
-                </configuration>
-            </plugin>
-        </plugins>
-    </build>
     <packaging>jar</packaging>
 
     <parent>
@@ -61,6 +49,19 @@
         </dependency>
     </dependencies>
 
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>9</source>
+                    <target>9</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
     <properties>
         <junit.version>5.9.2</junit.version>
         <roaringbitmap.version>0.9.38</roaringbitmap.version>

core-java-modules/core-java-collections-list-5/pom.xml

@@ -55,7 +55,6 @@
             <version>${org.json.version}</version>
             <scope>test</scope>
         </dependency>
-
     </dependencies>
 
     <properties>

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

@@ -1,2 +1,6 @@
 ## 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)
+- [Reset ListIterator to First Element of the List in Java](https://www.baeldung.com/java-reset-listiterator)

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-6/pom.xml

@@ -27,7 +27,7 @@
         <dependency>
             <groupId>com.google.code.gson</groupId>
             <artifactId>gson</artifactId>
-            <version>2.8.9</version>
+            <version>2.10.1</version>
         </dependency>
         <dependency>
             <groupId>org.json</groupId>

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-collections-set/pom.xml

@@ -41,7 +41,7 @@
     </build>
 
     <properties>
-        <gson.version>2.8.5</gson.version>
+        <gson.version>2.10.1</gson.version>
     </properties>
 
 </project>

core-java-modules/core-java-concurrency-advanced-5/src/main/java/com/baeldung/countdownlatchvssemaphore/CountDownLatchDemo.java

@@ -0,0 +1,33 @@
+package com.baeldung.countdownlatchvssemaphore;
+
+import java.util.concurrent.CountDownLatch;
+
+public class CountDownLatchDemo {
+
+    public static void main(String[] args) throws InterruptedException {
+        // Create a CountDownLatch with an initial count equal to the number of tasks to be completed
+        int numberOfTasks = 3;
+        CountDownLatch latch = new CountDownLatch(numberOfTasks);
+
+        // Simulate completion of tasks by worker threads
+        for (int i = 1; i <= numberOfTasks; i++) {
+            new Thread(() -> {
+                System.out.println("Task completed by Thread " + Thread.currentThread()
+                    .getId());
+
+                // Decrement the latch count to signal completion of a task
+                latch.countDown();
+            }).start();
+        }
+
+        // Main thread waits until all tasks are completed
+        latch.await();
+        System.out.println("All tasks completed. Main thread proceeds.");
+
+        // Attempting to reset will have no effect
+        latch.countDown();
+        // Latch is already at zero, await() returns immediately
+        latch.await(); // This line won't block
+        System.out.println("Latch is already at zero and cannot be reset.");
+    }
+}

core-java-modules/core-java-concurrency-advanced-5/src/main/java/com/baeldung/countdownlatchvssemaphore/SemaphoreDemo.java

@@ -0,0 +1,42 @@
+package com.baeldung.countdownlatchvssemaphore;
+
+import java.util.concurrent.Semaphore;
+
+public class SemaphoreDemo {
+
+    public static void main(String[] args) {
+        // Create a Semaphore with a fixed number of permits
+        int NUM_PERMITS = 3;
+        Semaphore semaphore = new Semaphore(NUM_PERMITS);
+
+        // Simulate resource access by worker threads
+        for (int i = 1; i <= 5; i++) {
+            new Thread(() -> {
+                try {
+                    // Acquire a permit to access the resource
+                    semaphore.acquire();
+                    System.out.println("Thread " + Thread.currentThread().getId() + " accessing resource.");
+
+                    // Simulate resource usage
+                    Thread.sleep(2000);
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                } finally {
+                    // Release the permit after resource access is complete
+                    semaphore.release();
+                }
+            }).start();
+        }
+
+        // Simulate resetting the Semaphore by releasing additional permits after a delay
+        try {
+            Thread.sleep(5000);
+
+            // Resetting the semaphore permits to the initial count
+            semaphore.release(NUM_PERMITS);
+            System.out.println("Semaphore permits reset to initial count.");
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+}

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-console/README.md

@@ -8,3 +8,4 @@
 - [System.console() vs. System.out](https://www.baeldung.com/java-system-console-vs-system-out)
 - [How to Log to the Console in Color](https://www.baeldung.com/java-log-console-in-color)
 - [Create Table Using ASCII in a Console in Java](https://www.baeldung.com/java-console-ascii-make-table)
+- [Printing Message on Console without Using main() Method in Java](https://www.baeldung.com/java-no-main-print-message-console)

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

@@ -0,0 +1,6 @@
+## Core Date Operations (Part 4)
+This module contains articles about date operations in Java.
+
+### Relevant Articles:
+- [Calculate Number of Weekdays Between Two Dates in Java](https://www.baeldung.com/java-count-weekdays-between-two-dates)
+- [Convert Long to Date in Java](https://www.baeldung.com/java-long-date-conversion)

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;
+    }
+
+
+}