Merge branch 'master' of https://github.com/eugenp/tutorials

algorithms-miscellaneous-3/README.md

@@ -1,4 +1,4 @@
-## Relevant articles:
+## Relevant Articles:
 
 - [Java Two Pointer Technique](https://www.baeldung.com/java-two-pointer-technique)
 - [Implementing Simple State Machines with Java Enums](https://www.baeldung.com/java-enum-simple-state-machine)

core-groovy-2/src/main/groovy/com/baeldung/metaprogramming/Employee.groovy

@@ -0,0 +1,45 @@
+package com.baeldung.metaprogramming
+
+import groovy.transform.AutoClone
+import groovy.transform.Canonical
+import groovy.transform.EqualsAndHashCode
+import groovy.transform.ToString
+import groovy.transform.TupleConstructor
+import groovy.util.logging.*
+
+@Canonical
+@TupleConstructor
+@EqualsAndHashCode
+@ToString(includePackage=false, excludes=['id'])
+@Log 
+@AutoClone
+class Employee {
+
+    long id
+    String firstName
+    String lastName
+    int age
+
+    //method to catch missing property's getter
+    def propertyMissing(String propertyName) {
+        log.info "$propertyName is not available"
+        "property '$propertyName' is not available"
+    }
+
+    //method to catch missing property's setter
+    def propertyMissing(String propertyName, propertyValue) {
+        println "property '$propertyName' is not available"
+        log.info "$propertyName is not available"
+        "property '$propertyName' is not available"
+    }
+
+    def methodMissing(String methodName, def methodArgs) {
+        log.info "$methodName is not defined"
+        "method '$methodName' is not defined"
+    }
+    
+    def logEmp() {
+        log.info "Employee: $lastName, $firstName is of $age years age"
+    }
+
+}

core-groovy-2/src/main/groovy/com/baeldung/metaprogramming/extension/BasicExtensions.groovy

@@ -0,0 +1,30 @@
+package com.baeldung.metaprogramming.extension
+
+import com.baeldung.metaprogramming.Employee
+
+class BasicExtensions {
+    
+    static int getYearOfBirth(Employee self) {
+        return (new Date().getYear() + 1900) - self.age;
+    }
+    
+    static String capitalize(String self) {
+        return self.substring(0, 1).toUpperCase() + self.substring(1)
+    }
+
+    static void printCounter(Integer self) {
+        while (self>0) {
+            println self
+            self--
+        }
+    }
+    
+    static Long square(Long self) {
+        return self*self
+    }
+    
+    static BigDecimal cube(BigDecimal self) {
+        return self*self*self
+    }
+    
+}

core-groovy-2/src/main/groovy/com/baeldung/metaprogramming/extension/StaticEmployeeExtension.groovy

@@ -0,0 +1,10 @@
+package com.baeldung.metaprogramming.extension
+
+import com.baeldung.metaprogramming.Employee
+
+class StaticEmployeeExtension {
+    
+    static Employee getDefaultObj(Employee self) {
+        return new Employee(firstName: "firstName", lastName: "lastName", age: 20)
+    }
+}

core-groovy-2/src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule

@@ -0,0 +1,4 @@
+moduleName=core-groovy-2
+moduleVersion=1.0-SNAPSHOT
+extensionClasses=com.baeldung.metaprogramming.extension.BasicExtensions
+staticExtensionClasses=com.baeldung.metaprogramming.extension.StaticEmployeeExtension

core-groovy-2/src/test/groovy/com/baeldung/metaprogramming/MetaprogrammingUnitTest.groovy

@@ -0,0 +1,118 @@
+package com.baeldung.metaprogramming
+
+import groovy.time.TimeCategory
+
+class MetaprogrammingUnitTest extends GroovyTestCase {
+
+    Employee emp = new Employee(firstName: "Norman", lastName: "Lewis")
+
+    void testPropertyMissing() {
+        assert emp.address == "property 'address' is not available"
+    }
+
+    void testMethodMissing() {
+        Employee emp = new Employee()
+        try {
+            emp.getFullName()
+        } catch(MissingMethodException e) {
+            println "method is not defined"
+        }
+        assert emp.getFullName() == "method 'getFullName' is not defined"
+    }
+
+    void testMetaClassProperty() {
+        Employee.metaClass.address = ""
+        emp = new Employee(firstName: "Norman", lastName: "Lewis", address: "US")
+        assert emp.address == "US"
+    }
+
+    void testMetaClassMethod() {
+        emp.metaClass.getFullName = {
+            "$lastName, $firstName"
+        }
+        assert emp.getFullName() == "Lewis, Norman"
+    }
+
+    void testMetaClassConstructor() {
+        try {
+            Employee emp = new Employee("Norman")
+        } catch(GroovyRuntimeException e) {
+            assert e.message == "Could not find matching constructor for: com.baeldung.metaprogramming.Employee(String)"
+        }
+
+        Employee.metaClass.constructor = { String firstName ->
+            new Employee(firstName: firstName)
+        }
+
+        Employee norman = new Employee("Norman")
+        assert norman.firstName == "Norman"
+        assert norman.lastName == null
+    }
+
+    void testJavaMetaClass() {
+        String.metaClass.capitalize = { String str ->
+            str.substring(0, 1).toUpperCase() + str.substring(1);
+        }
+        assert "norman".capitalize() == "Norman"
+    }
+
+    void testEmployeeExtension() {
+        Employee emp = new Employee(age: 28)
+        assert emp.getYearOfBirth() == 1991
+    }
+
+    void testJavaClassesExtensions() {
+        5.printCounter()
+
+        assert 40l.square() == 1600l
+
+        assert (2.98).cube() == 26.463592
+    }
+
+    void testStaticEmployeeExtension() {
+        assert Employee.getDefaultObj().firstName == "firstName"
+        assert Employee.getDefaultObj().lastName == "lastName"
+        assert Employee.getDefaultObj().age == 20
+    }
+
+    void testToStringAnnotation() {
+        Employee employee = new Employee()
+        employee.id = 1
+        employee.firstName = "norman"
+        employee.lastName = "lewis"
+        employee.age = 28
+
+        assert employee.toString() == "Employee(norman, lewis, 28)"
+    }
+
+    void testTupleConstructorAnnotation() {
+        Employee norman = new Employee(1, "norman", "lewis", 28)
+        assert norman.toString() == "Employee(norman, lewis, 28)"
+
+        Employee snape = new Employee(2, "snape")
+        assert snape.toString() == "Employee(snape, null, 0)"
+
+    }
+    
+    void testEqualsAndHashCodeAnnotation() {
+        Employee norman = new Employee(1, "norman", "lewis", 28)
+        Employee normanCopy = new Employee(1, "norman", "lewis", 28)
+        assert norman.equals(normanCopy)
+        assert norman.hashCode() == normanCopy.hashCode()
+    }
+    
+    void testAutoCloneAnnotation() {
+        try {
+            Employee norman = new Employee(1, "norman", "lewis", 28)
+            def normanCopy = norman.clone()
+            assert norman == normanCopy
+        } catch(CloneNotSupportedException e) {
+            e.printStackTrace()
+        }
+    }
+
+    void testLoggingAnnotation() {
+        Employee employee = new Employee(1, "Norman", "Lewis", 28)
+        employee.logEmp()
+    }
+}

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

@@ -7,3 +7,4 @@
 - [How to Delay Code Execution in Java](https://www.baeldung.com/java-delay-code-execution)
 - [Run JAR Application With Command Line Arguments](https://www.baeldung.com/java-run-jar-with-arguments)
 - [Java 8 Stream skip() vs limit()](https://www.baeldung.com/java-stream-skip-vs-limit)
+- [Guide to Java BiFunction Interface](https://www.baeldung.com/java-bifunction-interface)

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

@@ -7,7 +7,7 @@
 - [Check if a Java Array Contains a Value](http://www.baeldung.com/java-array-contains-value)
 - [Initializing Arrays in Java](http://www.baeldung.com/java-initialize-array)
 - [Guide to the java.util.Arrays Class](http://www.baeldung.com/java-util-arrays)
-- [Jagged Arrays In Java](http://www.baeldung.com/java-jagged-arrays)
+- [Multi-Dimensional Arrays In Java](http://www.baeldung.com/java-jagged-arrays)
 - [Find Sum and Average in a Java Array](http://www.baeldung.com/java-array-sum-average)
 - [Arrays in Java: A Reference Guide](https://www.baeldung.com/java-arrays-guide)
 - [How to Invert an Array in Java](http://www.baeldung.com/java-invert-array)
@@ -16,3 +16,4 @@
 - [Sorting Arrays in Java](https://www.baeldung.com/java-sorting-arrays)
 - [Convert a Float to a Byte Array in Java](https://www.baeldung.com/java-convert-float-to-byte-array)
 - [Converting Between Stream and Array in Java](https://www.baeldung.com/java-stream-to-array)
+- [Removing an Element from an Array in Java](https://www.baeldung.com/java-array-remove-element)

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

@@ -0,0 +1,3 @@
+### Relevant Articles
+
+- [Design Strategies for Decoupling Java Modules](https://www.baeldung.com/java-modules-decoupling-design-strategies)

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

@@ -0,0 +1,43 @@
+<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>
+    <groupId>com.baeldung</groupId>
+    <artifactId>core-java-lang-operators</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-lang-operators</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>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj-core.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-lang-operators</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+        <!-- testing -->
+        <assertj-core.version>3.10.0</assertj-core.version>
+    </properties>
+
+</project>

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/incrementdecrementunaryoperators/IncrementDecrementUnaryOperatorUnitTest.java

@@ -0,0 +1,64 @@
+package com.baeldung.incrementdecrementunaryoperators;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+public class IncrementDecrementUnaryOperatorUnitTest {
+
+    @Test
+    public void givenAnOperand_whenUsingPreIncrementUnaryOperator_thenOperandIsIncrementedByOne() {
+        int operand = 1;
+        ++operand;
+        assertThat(operand).isEqualTo(2);
+    }
+
+    @Test
+    public void givenANumber_whenUsingPreIncrementUnaryOperatorInEvaluation_thenNumberIsIncrementedByOne() {
+        int operand = 1;
+        int number = ++operand;
+        assertThat(number).isEqualTo(2);
+    }
+
+    @Test
+    public void givenAnOperand_whenUsingPreDecrementUnaryOperator_thenOperandIsDecrementedByOne() {
+        int operand = 1;
+        --operand;
+        assertThat(operand).isEqualTo(0);
+    }
+
+    @Test
+    public void givenANumber_whenUsingPreDecrementUnaryOperatorInEvaluation_thenNumberIsDecrementedByOne() {
+        int operand = 1;
+        int number = --operand;
+        assertThat(number).isEqualTo(0);
+    }
+
+    @Test
+    public void givenAnOperand_whenUsingPostIncrementUnaryOperator_thenOperandIsIncrementedByOne() {
+        int operand = 1;
+        operand++;
+        assertThat(operand).isEqualTo(2);
+    }
+
+    @Test
+    public void givenANumber_whenUsingPostIncrementUnaryOperatorInEvaluation_thenNumberIsSameAsOldValue() {
+        int operand = 1;
+        int number = operand++;
+        assertThat(number).isEqualTo(1);
+    }
+
+    @Test
+    public void givenAnOperand_whenUsingPostDecrementUnaryOperator_thenOperandIsDecrementedByOne() {
+        int operand = 1;
+        operand--;
+        assertThat(operand).isEqualTo(0);
+    }
+
+    @Test
+    public void givenANumber_whenUsingPostDecrementUnaryOperatorInEvaluation_thenNumberIsSameAsOldValue() {
+        int operand = 1;
+        int number = operand--;
+        assertThat(number).isEqualTo(1);
+    }
+}

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

@@ -18,3 +18,4 @@
 - [The Modulo Operator in Java](https://www.baeldung.com/modulo-java)
 - [Ternary Operator In Java](https://www.baeldung.com/java-ternary-operator)
 - [Java instanceof Operator](https://www.baeldung.com/java-instanceof)
+- [Breaking Out of Nested Loops](https://www.baeldung.com/java-breaking-out-nested-loop)

core-java-modules/core-java-networking-2/.gitignore

@@ -1,25 +0,0 @@
-*.class
-
-0.*
-
-#folders#
-/target
-/neoDb*
-/data
-/src/main/webapp/WEB-INF/classes
-*/META-INF/*
-.resourceCache
-
-# Packaged files #
-*.jar
-*.war
-*.ear
-
-# Files generated by integration tests
-backup-pom.xml
-/bin/
-/temp
-
-#IntelliJ specific
-.idea/
-*.iml

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

@@ -1,3 +1,3 @@
-## Relevant articles:
+## Relevant Articles:
 
-- [Determine File Creating Date in Java](https://www.baeldung.com/java-file-creation-date)
+- [Determine File Creation Date in Java](https://www.baeldung.com/java-file-creation-date)

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

@@ -10,3 +10,4 @@
 - [SSL Handshake Failures](https://www.baeldung.com/java-ssl-handshake-failures)
 - [SHA-256 and SHA3-256 Hashing in Java](https://www.baeldung.com/sha-256-hashing-java)
 - [Enabling TLS v1.2 in Java 7](https://www.baeldung.com/java-7-tls-v12)
+- [The Java SecureRandom Class](https://www.baeldung.com/java-secure-random)

core-java-modules/pom.xml

@@ -17,6 +17,7 @@
         <module>pre-jpms</module>
         <module>core-java-exceptions</module>
         <module>core-java-optional</module>
+        <module>core-java-lang-operators</module>
         <module>core-java-networking-2</module>
     </modules>
     

data-structures/README.md

@@ -1,4 +1,5 @@
 ## Relevant articles:
 
-[The Trie Data Structure in Java](https://www.baeldung.com/trie-java)
-[Implementing a Binary Tree in Java](https://www.baeldung.com/java-binary-tree)
+- [The Trie Data Structure in Java](https://www.baeldung.com/trie-java)
+- [Implementing a Binary Tree in Java](https://www.baeldung.com/java-binary-tree)
+- [Depth First Search in Java](https://www.baeldung.com/java-depth-first-search)

data-structures/src/main/java/com/baeldung/graph/Graph.java

@@ -2,6 +2,7 @@ package com.baeldung.graph;
 
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Stack;
@@ -29,7 +30,7 @@ public class Graph {
         while (!stack.isEmpty()) {
             int current = stack.pop();
             isVisited[current] = true;
-            System.out.print(" " + current);
+            visit(current);
             for (int dest : adjVertices.get(current)) {
                 if (!isVisited[dest])
                     stack.push(dest);
@@ -44,29 +45,30 @@ public class Graph {
 
     private void dfsRecursive(int current, boolean[] isVisited) {
         isVisited[current] = true;
-        System.out.print(" " + current);
+        visit(current);
         for (int dest : adjVertices.get(current)) {
             if (!isVisited[dest])
                 dfsRecursive(dest, isVisited);
         }
     }
 
-    public void topologicalSort(int start) {
-        Stack<Integer> result = new Stack<Integer>();
+    public List<Integer> topologicalSort(int start) {
+        LinkedList<Integer> result = new LinkedList<Integer>();
         boolean[] isVisited = new boolean[adjVertices.size()];
         topologicalSortRecursive(start, isVisited, result);
-        while (!result.isEmpty()) {
-            System.out.print(" " + result.pop());
-        }
+        return result;
     }
 
-    private void topologicalSortRecursive(int current, boolean[] isVisited, Stack<Integer> result) {
+    private void topologicalSortRecursive(int current, boolean[] isVisited, LinkedList<Integer> result) {
         isVisited[current] = true;
         for (int dest : adjVertices.get(current)) {
             if (!isVisited[dest])
                 topologicalSortRecursive(dest, isVisited, result);
         }
-        result.push(current);
+        result.addFirst(current);
     }
 
+    private void visit(int value) {
+        System.out.print(" " + value);        
+    }
 }

data-structures/src/main/java/com/baeldung/tree/BinaryTree.java

@@ -103,14 +103,14 @@ public class BinaryTree {
     public void traverseInOrder(Node node) {
         if (node != null) {
             traverseInOrder(node.left);
-            System.out.print(" " + node.value);
+            visit(node.value);
             traverseInOrder(node.right);
         }
     }
 
     public void traversePreOrder(Node node) {
         if (node != null) {
-            System.out.print(" " + node.value);
+            visit(node.value);
             traversePreOrder(node.left);
             traversePreOrder(node.right);
         }
@@ -120,7 +120,7 @@ public class BinaryTree {
         if (node != null) {
             traversePostOrder(node.left);
             traversePostOrder(node.right);
-            System.out.print(" " + node.value);
+            visit(node.value);
         }
     }
 
@@ -159,7 +159,7 @@ public class BinaryTree {
                 stack.push(current);                
             }
             current = stack.pop();
-            System.out.print(" " + current.value);
+            visit(current.value);
             if(current.right != null) {
                 current = current.right;                
                 stack.push(current);
@@ -173,7 +173,7 @@ public class BinaryTree {
         stack.push(root);
         while(! stack.isEmpty()) {
             current = stack.pop();
-            System.out.print(" " + current.value);
+            visit(current.value);
             
             if(current.right != null)
                 stack.push(current.right);
@@ -196,7 +196,7 @@ public class BinaryTree {
 
             if (!hasChild || isPrevLastChild) {
                 current = stack.pop();
-                System.out.print(" " + current.value);
+                visit(current.value);
                 prev = current;
             } else {
                 if (current.right != null) {
@@ -209,6 +209,9 @@ public class BinaryTree {
         }   
     }    
     
+    private void visit(int value) {
+        System.out.print(" " + value);        
+    }
     
     class Node {
         int value;

data-structures/src/test/java/com/baeldung/graph/GraphUnitTest.java

@@ -1,5 +1,7 @@
 package com.baeldung.graph;
 
+import java.util.List;
+
 import org.junit.Test;
 
 public class GraphUnitTest {
@@ -15,7 +17,8 @@ public class GraphUnitTest {
     @Test
     public void givenDirectedGraph_whenGetTopologicalSort_thenPrintValuesSorted() {
         Graph graph = createDirectedGraph();
-        graph.topologicalSort(0);
+        List<Integer> list = graph.topologicalSort(0);
+        System.out.println(list);
     }
 
     private Graph createDirectedGraph() {

jackson-2/README.md

@@ -2,7 +2,7 @@
 
 ## Jackson Cookbooks and Examples
 
-###The Course
+### The Course
 The "REST With Spring" Classes: http://bit.ly/restwithspring
 
 ### Relevant Articles: 
@@ -10,3 +10,4 @@ The "REST With Spring" Classes: http://bit.ly/restwithspring
 - [How to Process YAML with Jackson](https://www.baeldung.com/jackson-yaml)
 - [Working with Tree Model Nodes in Jackson](https://www.baeldung.com/jackson-json-node-tree-model)
 - [Converting JSON to CSV in Java](https://www.baeldung.com/java-converting-json-to-csv)
+- [Compare Two JSON Objects with Jackson](https://www.baeldung.com/jackson-compare-two-json-objects)

java-dates-2/README.md

@@ -1,3 +1,4 @@
 ## Relevant Articles:
 - [Converting Between LocalDate and XMLGregorianCalendar](https://www.baeldung.com/java-localdate-to-xmlgregoriancalendar)
 - [Convert Time to Milliseconds in Java](https://www.baeldung.com/java-time-milliseconds)
+- [Check If a String Is a Valid Date in Java](https://www.baeldung.com/java-string-valid-date)

java-dates/README.md

@@ -29,3 +29,4 @@
 - [A Guide to SimpleDateFormat](https://www.baeldung.com/java-simple-date-format)
 - [ZoneOffset in Java](https://www.baeldung.com/java-zone-offset)
 - [Differences Between ZonedDateTime and OffsetDateTime](https://www.baeldung.com/java-zoneddatetime-offsetdatetime)
+- [Introduction to Joda-Time](http://www.baeldung.com/joda-time)

java-numbers-2/.gitignore

@@ -1,26 +0,0 @@
-*.class
-
-0.*
-
-#folders#
-/target
-/neoDb*
-/data
-/src/main/webapp/WEB-INF/classes
-*/META-INF/*
-.resourceCache
-
-# Packaged files #
-*.jar
-*.war
-*.ear
-
-# Files generated by integration tests
-*.txt
-backup-pom.xml
-/bin/
-/temp
-
-#IntelliJ specific
-.idea/
-*.iml

java-strings-2/README.MD

@@ -1,7 +0,0 @@
-## Relevant Articles
-
-- [Java Localization – Formatting Messages](https://www.baeldung.com/java-localization-messages-formatting)
-- [Check If a String Contains a Substring](https://www.baeldung.com/java-string-contains-substring)
-- [Removing Stopwords from a String in Java](https://www.baeldung.com/java-string-remove-stopwords)
-- [Blank and Empty Strings in Java](https://www.baeldung.com/java-blank-empty-strings)
-- [String Initialization in Java](https://www.baeldung.com/java-string-initialization)

java-strings-2/README.md

@@ -0,0 +1,25 @@
+## Relevant Articles:
+
+- [Java Localization – Formatting Messages](https://www.baeldung.com/java-localization-messages-formatting)
+- [Check If a String Contains a Substring](https://www.baeldung.com/java-string-contains-substring)
+- [Removing Stopwords from a String in Java](https://www.baeldung.com/java-string-remove-stopwords)
+- [Java – Generate Random String](http://www.baeldung.com/java-random-string)
+- [Image to Base64 String Conversion](http://www.baeldung.com/java-base64-image-string)
+- [Java Base64 Encoding and Decoding](https://www.baeldung.com/java-base64-encode-and-decode)
+- [Generate a Secure Random Password in Java](https://www.baeldung.com/java-generate-secure-password)
+- [Removing Repeated Characters from a String](https://www.baeldung.com/java-remove-repeated-char)
+- [Join Array of Primitives with Separator in Java](https://www.baeldung.com/java-join-primitive-array)
+- [Pad a String with Zeros or Spaces in Java](https://www.baeldung.com/java-pad-string)
+- [Remove Emojis from a Java String](https://www.baeldung.com/java-string-remove-emojis)
+- [Convert a Comma Separated String to a List in Java](https://www.baeldung.com/java-string-with-separator-to-list)
+- [Guide to java.util.Formatter](http://www.baeldung.com/java-string-formatter)
+- [Remove Leading and Trailing Characters from a String](https://www.baeldung.com/java-remove-trailing-characters)
+- [Concatenating Strings In Java](https://www.baeldung.com/java-strings-concatenation)
+- [Java String Interview Questions and Answers](https://www.baeldung.com/java-string-interview-questions)
+- [Check if a String is a Pangram in Java](https://www.baeldung.com/java-string-pangram)
+- [Check If a String Contains Multiple Keywords](https://www.baeldung.com/string-contains-multiple-words)
+- [Checking for Empty or Blank Strings in Java](https://www.baeldung.com/java-blank-empty-strings)
+- [String Initialization in Java](https://www.baeldung.com/java-string-initialization)
+- [Java Multi-line String](https://www.baeldung.com/java-multiline-string)
+- [Checking If a String Is a Repeated Substring](https://www.baeldung.com/java-repeated-substring)
+- [How to Reverse a String in Java](https://www.baeldung.com/java-reverse-string)

java-strings-2/pom.xml

@@ -40,6 +40,16 @@
             <artifactId>commons-lang3</artifactId>
             <version>${commons-lang3.version}</version>
         </dependency>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-codec</groupId>
+            <artifactId>commons-codec</artifactId>
+            <version>${commons-codec.version}</version>
+        </dependency>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
@@ -52,32 +62,54 @@
             <version>${org.hamcrest.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <!-- Added for password generation -->
+        <dependency>
+            <groupId>org.passay</groupId>
+            <artifactId>passay</artifactId>
+            <version>${passay.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-text</artifactId>
             <version>${commons-text.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.vdurmont</groupId>
+            <artifactId>emoji-java</artifactId>
+            <version>${emoji-java.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.ahocorasick</groupId>
+            <artifactId>ahocorasick</artifactId>
+            <version>${ahocorasick.version}</version>
+        </dependency>
         <dependency>
             <groupId>javax.validation</groupId>
             <artifactId>validation-api</artifactId>
-            <version>2.0.0.Final</version>
+            <version>${validation-api.version}</version>
         </dependency>
         <dependency>
             <groupId>org.hibernate.validator</groupId>
             <artifactId>hibernate-validator</artifactId>
-            <version>6.0.2.Final</version>
+            <version>${hibernate-validator.version}</version>
         </dependency>
         <dependency>
             <groupId>javax.el</groupId>
             <artifactId>javax.el-api</artifactId>
-            <version>3.0.0</version>
+            <version>${javax.el-api.version}</version>
         </dependency>
         <dependency>
             <groupId>org.glassfish.web</groupId>
             <artifactId>javax.el</artifactId>
-            <version>2.2.6</version>
+            <version>${javax.el.version}</version>
         </dependency>
-
     </dependencies>
 
     <build>
@@ -105,9 +137,19 @@
 
     <properties>
         <commons-lang3.version>3.8.1</commons-lang3.version>
+        <commons-codec.version>1.10</commons-codec.version>
+        <passay.version>1.3.1</passay.version>
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <emoji-java.version>4.0.0</emoji-java.version>
+        <ahocorasick.version>0.4.0</ahocorasick.version>
         <icu4j.version>61.1</icu4j.version>
         <guava.version>28.0-jre</guava.version>
         <commons-text.version>1.4</commons-text.version>
+        <validation-api.version>2.0.0.Final</validation-api.version>
+        <hibernate-validator.version>6.0.2.Final</hibernate-validator.version>
+        <javax.el-api.version>3.0.0</javax.el-api.version>
+        <javax.el.version>2.2.6</javax.el.version>
     </properties>
 
 </project>

java-strings-ops/README.md

@@ -0,0 +1,22 @@
+=========
+
+## Java Strings Cookbooks and Examples
+
+### Relevant Articles:
+- [Convert char to String in Java](http://www.baeldung.com/java-convert-char-to-string)
+- [Convert String to int or Integer in Java](http://www.baeldung.com/java-convert-string-to-int-or-integer)
+- [Java String Conversions](https://www.baeldung.com/java-string-conversions)
+- [Check if a String is a Palindrome](http://www.baeldung.com/java-palindrome)
+- [Comparing Strings in Java](http://www.baeldung.com/java-compare-strings)
+- [Check If a String Is Numeric in Java](http://www.baeldung.com/java-check-string-number)
+- [Get Substring from String in Java](https://www.baeldung.com/java-substring)
+- [How to Remove the Last Character of a String?](http://www.baeldung.com/java-remove-last-character-of-string)
+- [Add a Character to a String at a Given Position](https://www.baeldung.com/java-add-character-to-string)
+- [Count Occurrences of a Char in a String](http://www.baeldung.com/java-count-chars)
+- [Guide to Java String Pool](http://www.baeldung.com/java-string-pool)
+- [Split a String in Java](http://www.baeldung.com/java-split-string)
+- [Common String Operations in Java](https://www.baeldung.com/java-string-operations)
+- [Convert String to Byte Array and Reverse in Java](https://www.baeldung.com/java-string-to-byte-array)
+- [Java toString() Method](https://www.baeldung.com/java-tostring)
+- [CharSequence vs. String in Java](http://www.baeldung.com/java-char-sequence-string)
+- [StringBuilder and StringBuffer in Java](http://www.baeldung.com/java-string-builder-string-buffer)

java-strings-ops/pom.xml

@@ -0,0 +1,99 @@
+<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>
+    <groupId>com.baeldung</groupId>
+    <artifactId>java-strings-ops</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>java-strings-ops</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh-generator.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit-jupiter-api.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-library</artifactId>
+            <version>${org.hamcrest.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+        <finalName>java-strings-ops</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>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>${java.version}</source>
+                    <target>${java.version}</target>
+                    <compilerArgument>-parameters</compilerArgument>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <!-- util -->
+        <commons-lang3.version>3.8.1</commons-lang3.version>
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <guava.version>27.0.1-jre</guava.version>
+		<junit-jupiter-api.version>5.3.1</junit-jupiter-api.version>
+    </properties>
+
+</project>