Merge branch 'master' into bael-16656

algorithms-miscellaneous-3/README.md

@@ -16,4 +16,6 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Efficient Word Frequency Calculator in Java](https://www.baeldung.com/java-word-frequency)
 - [Interpolation Search in Java](https://www.baeldung.com/java-interpolation-search)
 - [The K-Means Clustering Algorithm in Java](https://www.baeldung.com/java-k-means-clustering-algorithm)
+- [Creating a Custom Annotation in Java](https://www.baeldung.com/java-custom-annotation)
+- [Breadth-First Search Algorithm in Java](https://www.baeldung.com/java-breadth-first-search)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-2) [[next -->]](/algorithms-miscellaneous-4)

algorithms-miscellaneous-4/README.md

@@ -1,7 +1,6 @@
 ## Algorithms - Miscellaneous
 
-This module contains articles about algorithms. Some classes of algorithms, e.g., [sorting](/../algorithms-sorting) and
-[genetic algorithms](/../algorithms-genetic), have their own dedicated modules. 
+This module contains articles about algorithms. Some classes of algorithms, e.g., [sorting](https://github.com/eugenp/tutorials/blob/algorithms-sorting) and [genetic algorithms](https://github.com/eugenp/tutorials/blob/algorithms-genetic), have their own dedicated modules.
 
 ### Relevant articles:
 
@@ -12,4 +11,4 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Find Substrings That Are Palindromes in Java](https://www.baeldung.com/java-palindrome-substrings)
 - [Find the Longest Substring without Repeating Characters](https://www.baeldung.com/java-longest-substring-without-repeated-characters)
 - [Permutations of an Array in Java](https://www.baeldung.com/java-array-permutations)
-- More articles: [[<-- prev]](/../algorithms-miscellaneous-3) [[next -->]](/../algorithms-miscellaneous-5)
+- More articles: [[<-- prev]](/algorithms-miscellaneous-3) [[next -->]](/algorithms-miscellaneous-5)

algorithms-miscellaneous-5/README.md

@@ -8,4 +8,5 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Converting Between Byte Arrays and Hexadecimal Strings in Java](https://www.baeldung.com/java-byte-arrays-hex-strings)
 - [Reversing a Binary Tree in Java](https://www.baeldung.com/java-reversing-a-binary-tree)
 - [Find If Two Numbers Are Relatively Prime in Java](https://www.baeldung.com/java-two-relatively-prime-numbers)
+- [Knapsack Problem Implementation in Java](https://www.baeldung.com/java-knapsack)
 - More articles: [[<-- prev]](/../algorithms-miscellaneous-4)

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/balancedbinarytree/BalancedBinaryTree.java

@@ -0,0 +1,33 @@
+package com.baeldung.algorithms.balancedbinarytree;
+
+public class BalancedBinaryTree {
+
+    public static boolean isBalanced(Tree tree) {
+        return isBalancedRecursive(tree, -1).isBalanced;
+    }
+
+    private static Result isBalancedRecursive(Tree tree, int depth) {
+        if (tree == null) {
+            return new Result(true, -1);
+        }
+
+        Result leftSubtreeResult = isBalancedRecursive(tree.left(), depth + 1);
+        Result rightSubtreeResult = isBalancedRecursive(tree.right(), depth + 1);
+
+        boolean isBalanced = Math.abs(leftSubtreeResult.height - rightSubtreeResult.height) <= 1;
+        boolean subtreesAreBalanced = leftSubtreeResult.isBalanced && rightSubtreeResult.isBalanced;
+        int height = Math.max(leftSubtreeResult.height, rightSubtreeResult.height) + 1;
+
+        return new Result(isBalanced && subtreesAreBalanced, height);
+    }
+
+    private static final class Result {
+        private final boolean isBalanced;
+        private final int height;
+
+        private Result(boolean isBalanced, int height) {
+            this.isBalanced = isBalanced;
+            this.height = height;
+        }
+    }
+}

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/balancedbinarytree/Tree.java

@@ -0,0 +1,34 @@
+package com.baeldung.algorithms.balancedbinarytree;
+
+public class Tree {
+    private final int value;
+    private final Tree left;
+    private final Tree right;
+
+    public Tree(int value, Tree left, Tree right) {
+        this.value = value;
+        this.left = left;
+        this.right = right;
+    }
+
+    public int value() {
+        return value;
+    }
+
+    public Tree left() {
+        return left;
+    }
+
+    public Tree right() {
+        return right;
+    }
+
+    @Override
+    public String toString() {
+        return String.format("[%s, %s, %s]",
+            value,
+            left == null ? "null" : left.toString(),
+            right == null ? "null" : right.toString()
+        );
+    }
+}

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/balancedbinarytree/BalancedBinaryTreeUnitTest.java

@@ -0,0 +1,26 @@
+package com.baeldung.algorithms.balancedbinarytree;
+
+import org.junit.Test;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertFalse;
+
+public class BalancedBinaryTreeUnitTest extends BinaryTreeDataProvider {
+
+    @Test
+    public void givenBalancedTrees_whenCallingIsBalanced_ShouldReturnTrue() {
+        for (Tree tree : balancedTrees()) {
+            assertTrue(toString(tree) + " should be balanced", BalancedBinaryTree.isBalanced(tree));
+        }
+    }
+
+    @Test
+    public void givenUnbalancedTrees_whenCallingIsBalanced_ShouldReturnFalse() {
+        for (Tree tree : unbalancedTrees()) {
+            assertFalse(toString(tree) + " should not be balanced", BalancedBinaryTree.isBalanced(tree));
+        }
+    }
+
+    private String toString(Tree tree) {
+        return tree != null ? tree.toString() : "null";
+    }
+}

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/balancedbinarytree/BinaryTreeDataProvider.java

@@ -0,0 +1,69 @@
+package com.baeldung.algorithms.balancedbinarytree;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+class BinaryTreeDataProvider {
+
+    static Collection<Tree> balancedTrees() {
+        return Arrays.asList(
+            null,
+            leaf(1),
+            tree(1, leaf(2), leaf(3)),
+            tree(
+                1,
+                leaf(2),
+                tree(3, leaf(4), null)
+            ),
+            tree(
+                1,
+                tree(
+                    2,
+                    tree(3, leaf(4), null),
+                    leaf(5)
+                ),
+                tree(
+                    6,
+                    leaf(7),
+                    tree(8, null, leaf(9))
+                )
+            )
+        );
+    }
+
+    static Collection<Tree> unbalancedTrees() {
+        return Arrays.asList(
+            tree(
+                1,
+                tree(2, leaf(3), null),
+                null
+            ),
+            tree(
+                1,
+                tree(
+                    2,
+                    tree(3, leaf(4), leaf(5)),
+                    null
+                ),
+                tree(6, leaf(7), null)
+            ),
+            tree(
+                1,
+                tree(2, leaf(3), null),
+                tree(
+                    4,
+                    tree(5, leaf(6), leaf(7)),
+                    null
+                )
+            )
+        );
+    }
+
+    private static Tree leaf(int value) {
+        return new Tree(value, null, null);
+    }
+
+    private static Tree tree(int value, Tree left, Tree right) {
+        return new Tree(value, left, right);
+    }
+}

algorithms-sorting/README.md

@@ -17,3 +17,4 @@ This module contains articles about sorting algorithms.
 - [Sorting Strings by Contained Numbers in Java](https://www.baeldung.com/java-sort-strings-contained-numbers)
 - [Radix Sort in Java](https://www.baeldung.com/java-radix-sort)
 - [Sorting a String Alphabetically in Java](https://www.baeldung.com/java-sort-string-alphabetically)
+- [Bucket Sort in Java](https://www.baeldung.com/java-bucket-sort)

code-generation/pom.xml

@@ -12,10 +12,16 @@
     </parent>
 
     <dependencies>
+        <dependency>
+            <groupId>com.google.auto.value</groupId>
+            <artifactId>auto-value-annotations</artifactId>
+            <version>${auto-value.version}</version>
+        </dependency>
         <dependency>
             <groupId>com.google.auto.value</groupId>
             <artifactId>auto-value</artifactId>
             <version>${auto-value.version}</version>
+            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>com.google.auto.factory</groupId>
@@ -43,9 +49,9 @@
     </dependencies>
 
     <properties>
-        <auto-value.version>1.3</auto-value.version>
-        <auto-factory.version>1.0-beta5</auto-factory.version>
-        <auto-service.version>1.0-rc5</auto-service.version>
+        <auto-value.version>1.6.6</auto-value.version>
+        <auto-factory.version>1.0-beta6</auto-factory.version>
+        <auto-service.version>1.0-rc6</auto-service.version>
         <guice.version>4.2.0</guice.version>
     </properties>
 

code-generation/src/main/java/com/baeldung/autovalue/Person.java

@@ -0,0 +1,38 @@
+package com.baeldung.autovalue;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import com.google.auto.value.AutoValue;
+
+@AutoValue
+public abstract class Person {
+
+    public abstract String name();
+
+    public abstract List<String> favoriteMovies();
+
+    public static Builder builder() {
+        return new AutoValue_Person.Builder();
+    }
+
+    @AutoValue.Builder
+    public static abstract class Builder {
+
+        public abstract Builder name(String value);
+
+        public abstract Builder favoriteMovies(List<String> value);
+
+        abstract List<String> favoriteMovies();
+
+        abstract Person autoBuild();
+
+        public Person build() {
+            List<String> favoriteMovies = favoriteMovies();
+            List<String> copy = Collections.unmodifiableList(new ArrayList<>(favoriteMovies));
+            favoriteMovies(copy);
+            return autoBuild();
+        }
+    }
+}

code-generation/src/test/java/com/baeldung/autovalue/PersonUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.autovalue;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.Test;
+
+/**
+ * Unit Test which verifies that the {@link Person} value object creates defensive copies of its favoriteMovies list.
+ */
+public class PersonUnitTest {
+
+    @Test
+    public void givenNewPerson_whenModifyOriginalList_thenValueObjectIsNotAlsoModified() {
+        // GIVEN new Person
+        List<String> originalFavoriteMoviesList = new ArrayList<String>();
+        originalFavoriteMoviesList.add("Training Day");
+        originalFavoriteMoviesList.add("Fast and the Furious");
+        Person person = Person.builder()
+            .name("Dan")
+            .favoriteMovies(originalFavoriteMoviesList)
+            .build();
+
+        // WHEN modify original list
+        originalFavoriteMoviesList.add("Friday");
+
+        // THEN Person remains unaffected
+        assertFalse(person.favoriteMovies()
+            .contains("Friday"));
+        assertEquals(2, person.favoriteMovies()
+            .size());
+    }
+
+}

core-groovy-2/README.md

@@ -12,4 +12,5 @@ This module contains articles about core Groovy concepts
 - [Concatenate Strings with Groovy](https://www.baeldung.com/groovy-concatenate-strings)
 - [Metaprogramming in Groovy](https://www.baeldung.com/groovy-metaprogramming)
 - [A Quick Guide to Working with Web Services in Groovy](https://www.baeldung.com/groovy-web-services)
+- [Categories in Groovy](https://www.baeldung.com/groovy-categories)
 - [[<-- Prev]](/core-groovy)

core-java-modules/core-java-9-streams/README.md

@@ -0,0 +1,6 @@
+## Core Java 9 streams
+
+This module contains articles about Java 9 streams
+
+### Relevant Articles: 
+- [How to Break from Java Stream forEach](https://www.baeldung.com/java-break-stream-foreach)

core-java-modules/core-java-9-streams/pom.xml

@@ -0,0 +1,31 @@
+<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-9-streams</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-9-streams</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-9-streams</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+    </properties>
+</project>

core-java-modules/core-java-9-streams/src/main/java/com/baeldung/streams/breakforeach/CustomForEach.java

@@ -1,4 +1,4 @@
-package com.baeldung.breakforeach;
+package com.baeldung.streams.breakforeach;
 
 import java.util.Spliterator;
 import java.util.function.BiConsumer;

core-java-modules/core-java-9-streams/src/main/java/com/baeldung/streams/breakforeach/CustomSpliterator.java

@@ -1,4 +1,4 @@
-package com.baeldung.breakforeach;
+package com.baeldung.streams.breakforeach;
 
 import java.util.Spliterator;
 import java.util.Spliterators;

core-java-modules/core-java-9-streams/src/main/java/com/baeldung/streams/breakforeach/CustomTakeWhile.java

@@ -1,4 +1,4 @@
-package com.baeldung.breakforeach;
+package com.baeldung.streams.breakforeach;
 
 import java.util.function.Predicate;
 import java.util.stream.Stream;

core-java-modules/core-java-9-streams/src/main/java/com/baeldung/streams/breakforeach/TakeWhileExample.java

@@ -1,4 +1,4 @@
-package com.baeldung.breakforeach;
+package com.baeldung.streams.breakforeach;
 
 import java.util.List;
 import java.util.stream.Stream;

core-java-modules/core-java-9-streams/src/test/java/com/baeldung/streams/breakforeach/BreakFromStreamForEachUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.breakforeach;
+package com.baeldung.streams.breakforeach;
 
 import org.junit.Test;
 

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

@@ -8,4 +8,5 @@
 - [Java @SafeVarargs Annotation](https://www.baeldung.com/java-safevarargs)
 - [Java @Deprecated Annotation](https://www.baeldung.com/java-deprecated)
 - [Overview of Java Built-in Annotations](https://www.baeldung.com/java-default-annotations)
-- [Creating a Custom Annotation in Java](https://www.baeldung.com/java-custom-annotation)
+- [Creating a Custom Annotation in Java](https://www.baeldung.com/java-custom-annotation)
+- [Efficient Word Frequency Calculator in Java](https://www.baeldung.com/java-word-frequency)

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

@@ -12,4 +12,5 @@ This module contains articles about Java arrays
 - [Intersection Between two Integer Arrays](https://www.baeldung.com/java-array-intersection)
 - [Removing an Element from an Array in Java](https://www.baeldung.com/java-array-remove-element)
 - [Removing the First Element of an Array](https://www.baeldung.com/java-array-remove-first-element)
+- [Adding an Element to a Java Array vs an ArrayList](https://www.baeldung.com/java-add-element-to-array-vs-list)
 - [[<-- Prev]](/core-java-modules/core-java-arrays)

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

@@ -12,4 +12,4 @@
 - [Sorting in Java](https://www.baeldung.com/java-sorting)
 - [Getting the Size of an Iterable in Java](https://www.baeldung.com/java-iterable-size)
 - [Java Null-Safe Streams from Collections](https://www.baeldung.com/java-null-safe-streams-from-collections)
-
+- [Operating on and Removing an Item from Stream](https://www.baeldung.com/java-use-remove-item-stream)

core-java-modules/core-java-collections-list-2/README.md

@@ -11,4 +11,5 @@ This module contains articles about the Java List collection
 - [Ways to Iterate Over a List in Java](https://www.baeldung.com/java-iterate-list)
 - [Flattening Nested Collections in Java](http://www.baeldung.com/java-flatten-nested-collections)
 - [Intersection of Two Lists in Java](https://www.baeldung.com/java-lists-intersection)
-- [[<-- Prev]](/core-java-modules/core-java-collections-list)[[Next -->]](/core-java-modules/core-java-collections-list-3)
+- [Searching for a String in an ArrayList](https://www.baeldung.com/java-search-string-arraylist)
+- [[<-- Prev]](/core-java-modules/core-java-collections-list)[[Next -->]](/core-java-modules/core-java-collections-list-3)

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

@@ -0,0 +1,17 @@
+<?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</artifactId>
+    <version>${project.parent.version}</version>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+</project>

core-java-modules/core-java-date-operations/src/main/java/com/baeldung/datetime/CalendarUtils.java

@@ -0,0 +1,15 @@
+package com.baeldung.datetime;
+
+import java.text.ParseException;
+import java.util.Calendar;
+import java.util.Date;
+
+public class CalendarUtils {
+
+    public static Calendar getPlusDays(Date date, int amount) throws ParseException {
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTime(date);
+        calendar.add(Calendar.DAY_OF_YEAR, amount);
+        return calendar;
+    }
+}

core-java-modules/core-java-date-operations/src/main/java/com/baeldung/datetime/DateUtils.java

@@ -0,0 +1,20 @@
+package com.baeldung.datetime;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public class DateUtils {
+
+    public static Date getNow() {
+        return new Date();
+    }
+
+    public static Date getDate(long millis) {
+        return new Date(millis);
+    }
+
+    public static Date getDate(String dateAsString, String pattern) throws ParseException {
+        return new SimpleDateFormat(pattern).parse(dateAsString);
+    }
+}

core-java-modules/core-java-date-operations/src/main/java/com/baeldung/datetime/sql/DateUtils.java

@@ -0,0 +1,21 @@
+package com.baeldung.datetime.sql;
+
+import java.sql.Date;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+
+public class DateUtils {
+
+    public static Date getNow() {
+        return new Date(System.currentTimeMillis());
+    }
+
+    public static Date getDate(String dateAsString) {
+        return Date.valueOf(dateAsString);
+    }
+
+    public static Date getDate(String dateAsString, String pattern) throws ParseException {
+        java.util.Date customUtilDate = new SimpleDateFormat(pattern).parse(dateAsString);
+        return new Date(customUtilDate.getTime());
+    }
+}

core-java-modules/core-java-date-operations/src/main/java/com/baeldung/datetime/sql/TimeUtils.java

@@ -0,0 +1,21 @@
+package com.baeldung.datetime.sql;
+
+import java.sql.Time;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+
+public class TimeUtils {
+
+    public static Time getNow() {
+        return new Time(System.currentTimeMillis());
+    }
+
+    public static Time getTime(String timeAsString) {
+        return Time.valueOf(timeAsString);
+    }
+
+    public static Time getTime(String dateAsString, String pattern) throws ParseException {
+        java.util.Date customUtilDate = new SimpleDateFormat(pattern).parse(dateAsString);
+        return new Time(customUtilDate.getTime());
+    }
+}

core-java-modules/core-java-date-operations/src/main/java/com/baeldung/datetime/sql/TimestampUtils.java

@@ -0,0 +1,21 @@
+package com.baeldung.datetime.sql;
+
+import java.sql.Timestamp;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+
+public class TimestampUtils {
+
+    public static Timestamp getNow() {
+        return new Timestamp(System.currentTimeMillis());
+    }
+
+    public static Timestamp getTimestamp(String timestampAsString) {
+        return Timestamp.valueOf(timestampAsString);
+    }
+
+    public static Timestamp getTimestamp(String dateAsString, String pattern) throws ParseException {
+        java.util.Date customUtilDate = new SimpleDateFormat(pattern).parse(dateAsString);
+        return new Timestamp(customUtilDate.getTime());
+    }
+}