MsMasterpull

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

cloud-foundry-uaa/cf-uaa-config/uaa.yml

@@ -1,12 +1,7 @@
 issuer:
   uri: http://localhost:8080/uaa
 
-spring_profiles: postgresql,default  
-  
-database.driverClassName: org.postgresql.Driver
-database.url: jdbc:postgresql:uaadb2
-database.username: postgres
-database.password: postgres  
+spring_profiles: default,hsqldb
   
 encryption:
   active_key_label: CHANGE-THIS-KEY

cloud-foundry-uaa/cf-uaa-oauth2-client/src/main/resources/application.properties

@@ -1,23 +1,11 @@
-# SECURITY OAUTH2 CLIENT (OAuth2ClientProperties)
-#spring.security.oauth2.client.provider.*= # OAuth provider details.
-#spring.security.oauth2.client.registration.*= # OAuth client registrations.
-
 server.port=8081
-#server.servlet.context-path=/uaa-client-webapp
 
-uaa.url=http://localhost:8080/uaa
 resource.server.url=http://localhost:8082
 
-spring.security.oauth2.client.registration.uaa.client-name=UAA OAuth2 Client
-spring.security.oauth2.client.registration.uaa.client-id=client1
-spring.security.oauth2.client.registration.uaa.client-secret=client1
-spring.security.oauth2.client.registration.uaa.authorization-grant-type=authorization_code
+spring.security.oauth2.client.registration.uaa.client-name=Web App Client
+spring.security.oauth2.client.registration.uaa.client-id=webappclient
+spring.security.oauth2.client.registration.uaa.client-secret=webappclientsecret
 spring.security.oauth2.client.registration.uaa.scope=resource.read,resource.write,openid,profile
-spring.security.oauth2.client.registration.uaa.redirect-uri=http://localhost:8081/login/oauth2/code/uaa
-#spring.security.oauth2.client.registration.uaa.redirect-uri=http://localhost:8081/**
 
-spring.security.oauth2.client.provider.uaa.token-uri=${uaa.url}/oauth/token
-spring.security.oauth2.client.provider.uaa.authorization-uri=${uaa.url}/oauth/authorize
-spring.security.oauth2.client.provider.uaa.jwk-set-uri=${uaa.url}/token_keys
-spring.security.oauth2.client.provider.uaa.user-info-uri=${uaa.url}/userinfo
-spring.security.oauth2.client.provider.uaa.user-name-attribute=user_name
+spring.security.oauth2.client.provider.uaa.issuer-uri=http://localhost:8080/uaa/oauth/token
+

cloud-foundry-uaa/cf-uaa-oauth2-resource-server/src/main/resources/application.properties

@@ -1,16 +1,3 @@
 server.port=8082
 
-uaa.url=http://localhost:8080/uaa
-
-#approch1
-spring.security.oauth2.resourceserver.jwt.issuer-uri=${uaa.url}/oauth/token
-
-#approch2
-#spring.security.oauth2.resourceserver.jwt.jwk-set-uri=${uaa.url}/token_key
-
-# SECURITY OAUTH2 CLIENT (OAuth2ClientProperties)
-#security.oauth2.client.client-id=client1
-#security.oauth2.client.client-secret=client1
-
-#security.oauth2.resource.jwt.key-uri=${uaa.url}/token_key
-#security.oauth2.resource.token-info-uri=${uaa.url}/oauth/check_token
+spring.security.oauth2.resourceserver.jwt.issuer-uri=http://localhost:8080/uaa/oauth/token

core-groovy/README.md

@@ -9,3 +9,5 @@
 - [A Quick Guide to Iterating a Map in Groovy](https://www.baeldung.com/groovy-map-iterating)
 - [An Introduction to Traits in Groovy](https://www.baeldung.com/groovy-traits)
 - [Lists in Groovy](https://www.baeldung.com/groovy-lists)
+- [Converting a String to a Date in Groovy](https://www.baeldung.com/groovy-string-to-date)
+- [Guide to I/O in Groovy](https://www.baeldung.com/groovy-io)

core-groovy/src/main/groovy/com/baeldung/Person.groovy

@@ -0,0 +1,37 @@
+package com.baeldung
+
+class Person {
+    private String firstname
+    private String lastname
+    private Integer age
+
+    Person(String firstname, String lastname, Integer age) {
+        this.firstname = firstname
+        this.lastname = lastname
+        this.age = age
+    }
+
+    String getFirstname() {
+        return firstname
+    }
+
+    void setFirstname(String firstname) {
+        this.firstname = firstname
+    }
+
+    String getLastname() {
+        return lastname
+    }
+
+    void setLastname(String lastname) {
+        this.lastname = lastname
+    }
+
+    Integer getAge() {
+        return age
+    }
+
+    void setAge(Integer age) {
+        this.age = age
+    }
+}

core-groovy/src/main/groovy/com/baeldung/closures/Closures.groovy

@@ -0,0 +1,87 @@
+package com.baeldung.closures
+
+class Closures {
+    
+    def printWelcome = {
+        println "Welcome to Closures!"
+    }
+    
+    def print = { name ->
+        println name
+    }
+    
+    def formatToLowerCase(name) {
+        return name.toLowerCase()
+    }
+    def formatToLowerCaseClosure = { name ->
+        return name.toLowerCase()
+    }
+    
+    def count=0
+    
+    def increaseCount = {
+        count++
+    }
+    
+    def greet = {
+        return "Hello! ${it}"
+    }
+   
+    def multiply = { x, y ->
+        return x*y
+    }
+    
+    def calculate = {int x, int y, String operation ->
+        
+        //log closure
+        def log = {
+            println "Performing $it"
+        }
+        
+        def result = 0    
+        switch(operation) {
+            case "ADD":
+                log("Addition")
+                result = x+y
+                break
+            case "SUB":
+                log("Subtraction")
+                result = x-y
+                break
+            case "MUL":
+                log("Multiplication")
+                result = x*y
+                break
+            case "DIV":
+                log("Division")
+                result = x/y
+                break
+        }
+        return result
+    }
+    
+    def addAll = { int... args ->
+        return args.sum()
+    }
+    
+    def volume(Closure areaCalculator, int... dimensions) {
+        if(dimensions.size() == 3) {
+            
+            //consider dimension[0] = length, dimension[1] = breadth, dimension[2] = height
+            //for cube and cuboid
+            return areaCalculator(dimensions[0], dimensions[1]) * dimensions[2]
+        } else if(dimensions.size() == 2) {
+            
+            //consider dimension[0] = radius, dimension[1] = height
+            //for cylinder and cone
+            return areaCalculator(dimensions[0]) * dimensions[1]
+        } else if(dimensions.size() == 1) {
+            
+            //consider dimension[0] = radius
+            //for sphere
+            return areaCalculator(dimensions[0]) * dimensions[0]
+        }
+        
+    }
+     
+}

core-groovy/src/main/groovy/com/baeldung/closures/Employee.groovy

@@ -0,0 +1,6 @@
+package com.baeldung.closures
+
+class Employee {
+    
+    String fullName
+}

core-groovy/src/test/groovy/com/baeldung/closures/ClosuresUnitTest.groovy

@@ -0,0 +1,80 @@
+package com.baeldung.closures
+
+import spock.lang.Specification
+
+class ClosuresUnitTest extends GroovyTestCase {
+
+    Closures closures = new Closures()
+    
+    void testDeclaration() {
+        
+        closures.print("Hello! Closure")
+        closures.formatToLowerCaseClosure("Hello! Closure")
+        
+        closures.print.call("Hello! Closure")
+        closures.formatToLowerCaseClosure.call("Hello! Closure")
+        
+    }
+    
+    void testClosureVsMethods() {   
+        assert closures.formatToLowerCase("TONY STARK") == closures.formatToLowerCaseClosure("Tony STark")
+    }
+    
+    void testParameters() {
+        //implicit parameter
+        assert closures.greet("Alex") == "Hello! Alex"
+        
+        //multiple parameters
+        assert closures.multiply(2, 4) == 8
+        
+        assert closures.calculate(12, 4, "ADD") == 16
+        assert closures.calculate(12, 4, "SUB") == 8
+        assert closures.calculate(43, 8, "DIV") == 5.375
+                
+        //varags
+        assert closures.addAll(12, 10, 14) == 36
+       
+    }
+    
+    void testClosureAsAnArgument() {
+        assert closures.volume({ l, b -> return l*b }, 12, 6, 10) == 720
+        
+        assert closures.volume({ radius -> return Math.PI*radius*radius/3 }, 5, 10) == Math.PI * 250/3
+    }
+    
+    void testGStringsLazyEvaluation() {
+        def name = "Samwell"
+        def welcomeMsg = "Welcome! $name"
+        
+        assert welcomeMsg == "Welcome! Samwell"
+        
+        // changing the name does not affect original interpolated value
+        name = "Tarly"
+        assert welcomeMsg != "Welcome! Tarly"
+        
+        def fullName = "Tarly Samson"
+        def greetStr = "Hello! ${-> fullName}"
+        
+        assert greetStr == "Hello! Tarly Samson"
+
+        // this time changing the variable affects the interpolated String's value
+        fullName = "Jon Smith"
+        assert greetStr == "Hello! Jon Smith"
+    }
+    
+    void testClosureInLists() {
+        def list = [10, 11, 12, 13, 14, true, false, "BUNTHER"]
+        list.each {
+            println it
+        }
+        
+        assert [13, 14] == list.findAll{ it instanceof Integer && it >= 13}
+    }
+    
+    void testClosureInMaps() {
+        def map = [1:10, 2:30, 4:5]
+        
+        assert [10, 60, 20] == map.collect{it.key * it.value}
+    }
+    
+}

core-groovy/src/test/groovy/com/baeldung/lists/ListTest.groovy

@@ -129,13 +129,13 @@ class ListTest{
         assertTrue(filterList.findAll{it > 3} == [4, 5, 6, 76])
 
         assertTrue(filterList.findAll{ it instanceof Number} == [2, 1, 3, 4, 5, 6, 76])
-        
+
         assertTrue(filterList.grep( Number )== [2, 1, 3, 4, 5, 6, 76])
-        
+
         assertTrue(filterList.grep{ it> 6 }== [76])
 
         def conditionList = [2, 1, 3, 4, 5, 6, 76]
-        
+
         assertFalse(conditionList.every{ it < 6})
 
         assertTrue(conditionList.any{ it%2 == 0})
@@ -165,7 +165,7 @@ class ListTest{
 
         def strList = ["na", "ppp", "as"]
         assertTrue(strList.max() == "ppp")
-        
+
         Comparator minc = {a,b -> a == b? 0: a < b? -1 : 1}
         def numberList = [3, 2, 0, 7]
         assertTrue(numberList.min(minc) == 0)

core-groovy/src/test/groovy/com/baeldung/lists/ListUnitTest.groovy

@@ -0,0 +1,58 @@
+package com.baeldung.lists
+
+import com.baeldung.Person
+import org.junit.Test
+
+import static org.junit.Assert.*
+
+class ListUnitTest {
+
+    private final personList = [
+      new Person("Regina", "Fitzpatrick", 25),
+      new Person("Abagail", "Ballard", 26),
+      new Person("Lucian", "Walter", 30),
+    ]
+
+    @Test
+    void whenListContainsElement_thenCheckReturnsTrue() {
+        def list = ['a', 'b', 'c']
+
+        assertTrue(list.indexOf('a') > -1)
+        assertTrue(list.contains('a'))
+    }
+
+    @Test
+    void whenListContainsElement_thenCheckWithMembershipOperatorReturnsTrue() {
+        def list = ['a', 'b', 'c']
+
+        assertTrue('a' in list)
+    }
+
+    @Test
+    void givenListOfPerson_whenUsingStreamMatching_thenShouldEvaluateList() {
+        assertTrue(personList.stream().anyMatch {it.age > 20})
+        assertFalse(personList.stream().allMatch {it.age < 30})
+    }
+
+    @Test
+    void givenListOfPerson_whenUsingCollectionMatching_thenShouldEvaluateList() {
+        assertTrue(personList.any {it.age > 20})
+        assertFalse(personList.every {it.age < 30})
+    }
+
+    @Test
+    void givenListOfPerson_whenUsingStreamFind_thenShouldReturnMatchingElements() {
+        assertTrue(personList.stream().filter {it.age > 20}.findAny().isPresent())
+        assertFalse(personList.stream().filter {it.age > 30}.findAny().isPresent())
+        assertTrue(personList.stream().filter {it.age > 20}.findAll().size() == 3)
+        assertTrue(personList.stream().filter {it.age > 30}.findAll().isEmpty())
+    }
+
+    @Test
+    void givenListOfPerson_whenUsingCollectionFind_thenShouldReturnMatchingElements() {
+        assertNotNull(personList.find {it.age > 20})
+        assertNull(personList.find {it.age > 30})
+        assertTrue(personList.findAll {it.age > 20}.size() == 3)
+        assertTrue(personList.findAll {it.age > 30}.isEmpty())
+    }
+}

core-groovy/src/test/groovy/com/baeldung/map/MapUnitTest.groovy

@@ -1,10 +1,18 @@
 package com.baeldung.map
 
-import static org.junit.Assert.*
+import com.baeldung.Person
 import org.junit.Test
 
+import static org.junit.Assert.*
+
 class MapUnitTest {
 
+    private final personMap = [
+      Regina : new Person("Regina", "Fitzpatrick", 25),
+      Abagail: new Person("Abagail", "Ballard", 26),
+      Lucian : new Person("Lucian", "Walter", 30)
+    ]
+
     @Test
     void whenUsingEach_thenMapIsIterated() {
         def map = [
@@ -63,7 +71,7 @@ class MapUnitTest {
             'FF6347' : 'Tomato',
             'FF4500' : 'Orange Red'
         ]
-        
+
         map.eachWithIndex { key, val, index ->
             def indent = ((index == 0 || index % 2 == 0) ? "   " : "")
             println "$indent Hex Code: $key = Color Name: $val"
@@ -82,4 +90,65 @@ class MapUnitTest {
             println "Hex Code: $entry.key = Color Name: $entry.value"
         }
     }
+
+    @Test
+    void whenMapContainsKeyElement_thenCheckReturnsTrue() {
+        def map = [a: 'd', b: 'e', c: 'f']
+
+        assertTrue(map.containsKey('a'))
+        assertFalse(map.containsKey('e'))
+        assertTrue(map.containsValue('e'))
+    }
+
+    @Test
+    void whenMapContainsKeyElement_thenCheckByMembershipReturnsTrue() {
+        def map = [a: 'd', b: 'e', c: 'f']
+
+        assertTrue('a' in map)
+        assertFalse('f' in map)
+    }
+
+    @Test
+    void whenMapContainsFalseBooleanValues_thenCheckReturnsFalse() {
+        def map = [a: true, b: false, c: null]
+
+        assertTrue(map.containsKey('b'))
+        assertTrue('a' in map)
+        assertFalse('b' in map)
+        assertFalse('c' in map)
+    }
+
+    @Test
+    void givenMapOfPerson_whenUsingStreamMatching_thenShouldEvaluateMap() {
+        assertTrue(personMap.keySet().stream().anyMatch {it == "Regina"})
+        assertFalse(personMap.keySet().stream().allMatch {it == "Albert"})
+        assertFalse(personMap.values().stream().allMatch {it.age < 30})
+        assertTrue(personMap.entrySet().stream().anyMatch {it.key == "Abagail" && it.value.lastname == "Ballard"})
+    }
+
+    @Test
+    void givenMapOfPerson_whenUsingCollectionMatching_thenShouldEvaluateMap() {
+        assertTrue(personMap.keySet().any {it == "Regina"})
+        assertFalse(personMap.keySet().every {it == "Albert"})
+        assertFalse(personMap.values().every {it.age < 30})
+        assertTrue(personMap.any {firstname, person -> firstname == "Abagail" && person.lastname == "Ballard"})
+    }
+
+    @Test
+    void givenMapOfPerson_whenUsingCollectionFind_thenShouldReturnElements() {
+        assertNotNull(personMap.find {it.key == "Abagail" && it.value.lastname == "Ballard"})
+        assertTrue(personMap.findAll {it.value.age > 20}.size() == 3)
+    }
+
+    @Test
+    void givenMapOfPerson_whenUsingStreamFind_thenShouldReturnElements() {
+        assertTrue(
+          personMap.entrySet().stream()
+            .filter {it.key == "Abagail" && it.value.lastname == "Ballard"}
+            .findAny().isPresent())
+        assertTrue(
+          personMap.entrySet().stream()
+            .filter {it.value.age > 20}
+            .findAll().size() == 3)
+    }
 }

core-groovy/src/test/groovy/com/baeldung/set/SetUnitTest.groovy

@@ -0,0 +1,16 @@
+package com.baeldung.set
+
+import org.junit.Test
+
+import static org.junit.Assert.assertTrue
+
+class SetUnitTest {
+
+    @Test
+    void whenSetContainsElement_thenCheckReturnsTrue() {
+        def set = ['a', 'b', 'c'] as Set
+
+        assertTrue(set.contains('a'))
+        assertTrue('a' in set)
+    }
+}

core-java-11/README.md

@@ -5,3 +5,4 @@
 - [Java 11 String API Additions](https://www.baeldung.com/java-11-string-api)
 - [Java 11 Nest Based Access Control](https://www.baeldung.com/java-nest-based-access-control)
 - [Exploring the New HTTP Client in Java 9 and 11](https://www.baeldung.com/java-9-http-client)
+- [An Introduction to Epsilon GC: A No-Op Experimental Garbage Collector](https://www.baeldung.com/jvm-epsilon-gc-garbage-collector)

core-java-11/src/modules/jlinkModule/com/baeldung/jlink/HelloWorld.java

@@ -0,0 +1,12 @@
+package com.baeldung.jlink;
+
+import java.util.logging.Logger;
+
+public class HelloWorld {
+
+    private static final Logger LOG = Logger.getLogger(HelloWorld.class.getName());
+
+    public static void main(String[] args) {
+        LOG.info("Hello World!");
+    }
+}

core-java-11/src/modules/jlinkModule/module-info.java

@@ -0,0 +1,3 @@
+module jlinkModule {
+    requires java.logging;
+}

core-java-12/pom.xml

@@ -0,0 +1,48 @@
+<?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>
+    <groupId>com.baeldung</groupId>
+    <artifactId>core-java-12</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-12</name>
+    <packaging>jar</packaging>
+    <url>http://maven.apache.org</url>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source.version}</source>
+                    <target>${maven.compiler.target.version}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <maven.compiler.source.version>12</maven.compiler.source.version>
+        <maven.compiler.target.version>12</maven.compiler.target.version>
+        <assertj.version>3.6.1</assertj.version>
+    </properties>
+
+</project>

core-java-12/src/test/java/com/baeldung/collectors/CollectorsUnitTest.java

@@ -0,0 +1,71 @@
+package com.baeldung.collectors;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+
+import org.junit.Test;
+
+import static java.util.stream.Collectors.maxBy;
+import static java.util.stream.Collectors.minBy;
+import static java.util.stream.Collectors.teeing;
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit tests for collectors additions in Java 12.
+ */
+public class CollectorsUnitTest {
+
+    @Test
+    public void whenTeeing_ItShouldCombineTheResultsAsExpected() {
+        List<Integer> numbers = Arrays.asList(42, 4, 2, 24);
+        Range range = numbers.stream()
+            .collect(teeing(minBy(Integer::compareTo), maxBy(Integer::compareTo), (min, max) -> new Range(min.orElse(null), max.orElse(null))));
+
+        assertThat(range).isEqualTo(new Range(2, 42));
+    }
+
+    /**
+     * Represents a closed range of numbers between {@link #min} and
+     * {@link #max}, both inclusive.
+     */
+    private static class Range {
+
+        private final Integer min;
+
+        private final Integer max;
+
+        Range(Integer min, Integer max) {
+            this.min = min;
+            this.max = max;
+        }
+
+        Integer getMin() {
+            return min;
+        }
+
+        Integer getMax() {
+            return max;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o)
+                return true;
+            if (o == null || getClass() != o.getClass())
+                return false;
+            Range range = (Range) o;
+            return Objects.equals(getMin(), range.getMin()) && Objects.equals(getMax(), range.getMax());
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(getMin(), getMax());
+        }
+
+        @Override
+        public String toString() {
+            return "Range{" + "min=" + min + ", max=" + max + '}';
+        }
+    }
+}

core-java-8/src/test/java/com/baeldung/java8/Java8SortUnitTest.java

@@ -124,11 +124,44 @@ public class Java8SortUnitTest {
 
     @Test
     public final void givenStreamCustomOrdering_whenSortingEntitiesByName_thenCorrectlySorted() {
-        
         final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
         final Comparator<Human> nameComparator = (h1, h2) -> h1.getName().compareTo(h2.getName());
         
         final List<Human> sortedHumans = humans.stream().sorted(nameComparator).collect(Collectors.toList());
         Assert.assertThat(sortedHumans.get(0), equalTo(new Human("Jack", 12)));
     }
+
+    @Test
+    public final void givenStreamComparatorOrdering_whenSortingEntitiesByName_thenCorrectlySorted() {
+        final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
+
+        final List<Human> sortedHumans = humans.stream().sorted(Comparator.comparing(Human::getName)).collect(Collectors.toList());
+        Assert.assertThat(sortedHumans.get(0), equalTo(new Human("Jack", 12)));
+    }
+
+    @Test
+    public final void givenStreamNaturalOrdering_whenSortingEntitiesByNameReversed_thenCorrectlySorted() {
+        final List<String> letters = Lists.newArrayList("B", "A", "C");
+
+        final List<String> reverseSortedLetters = letters.stream().sorted(Comparator.reverseOrder()).collect(Collectors.toList());
+        Assert.assertThat(reverseSortedLetters.get(0), equalTo("C"));
+    }
+
+    @Test
+    public final void givenStreamCustomOrdering_whenSortingEntitiesByNameReversed_thenCorrectlySorted() {
+        final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
+        final Comparator<Human> reverseNameComparator = (h1, h2) -> h2.getName().compareTo(h1.getName());
+
+        final List<Human> reverseSortedHumans = humans.stream().sorted(reverseNameComparator).collect(Collectors.toList());
+        Assert.assertThat(reverseSortedHumans.get(0), equalTo(new Human("Sarah", 10)));
+    }
+
+    @Test
+    public final void givenStreamComparatorOrdering_whenSortingEntitiesByNameReversed_thenCorrectlySorted() {
+        final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
+
+        final List<Human> reverseSortedHumans = humans.stream().sorted(Comparator.comparing(Human::getName, Comparator.reverseOrder())).collect(Collectors.toList());
+        Assert.assertThat(reverseSortedHumans.get(0), equalTo(new Human("Sarah", 10)));
+    }
+
 }

core-java-9/README.md

@@ -27,3 +27,6 @@
 - [Immutable Set in Java](https://www.baeldung.com/java-immutable-set)
 - [Multi-Release Jar Files](https://www.baeldung.com/java-multi-release-jar)
 - [Ahead of Time Compilation (AoT)](https://www.baeldung.com/ahead-of-time-compilation)
+- [Java 9 Process API Improvements](https://www.baeldung.com/java-9-process-api)
+- [Guide to java.lang.Process API](https://www.baeldung.com/java-process-api)
+

core-java-collections/README.md

@@ -33,3 +33,4 @@
 - [Differences Between HashMap and Hashtable](https://www.baeldung.com/hashmap-hashtable-differences)
 - [Java ArrayList vs Vector](https://www.baeldung.com/java-arraylist-vs-vector)
 - [Defining a Char Stack in Java](https://www.baeldung.com/java-char-stack)
+- [Time Comparison of Arrays.sort(Object[]) and Arrays.sort(int[])](https://www.baeldung.com/arrays-sortobject-vs-sortint)

core-java-concurrency-basic/README.md

@@ -16,3 +16,4 @@
 - [Life Cycle of a Thread in Java](http://www.baeldung.com/java-thread-lifecycle)
 - [Runnable vs. Callable in Java](http://www.baeldung.com/java-runnable-callable)
 - [What is Thread-Safety and How to Achieve it](https://www.baeldung.com/java-thread-safety)
+- [How to Start a Thread in Java](https://www.baeldung.com/java-start-thread)

core-java-jvm/README.md

@@ -0,0 +1,6 @@
+=========
+
+## Core Java JVM Cookbooks and Examples
+
+### Relevant Articles: 
+- [Method Inlining in the JVM](http://www.baeldung.com/method-inlining-in-the-jvm/)

core-java-jvm/pom.xml

@@ -0,0 +1,40 @@
+<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-jvm</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>core-java-jvm</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <commons-lang3.version>3.5</commons-lang3.version>
+        <assertj.version>3.6.1</assertj.version>
+    </properties>
+</project>

core-java-networking/src/main/java/com/baeldung/socket/read/Client.java

@@ -0,0 +1,29 @@
+package com.baeldung.socket.read;
+
+import java.net.*;
+import java.nio.charset.StandardCharsets;
+import java.io.*; 
+
+public class Client {
+    
+    public void runClient(String ip, int port) {
+        try {
+            Socket socket = new Socket(ip, port);
+            System.out.println("Connected to server ...");
+            DataInputStream in = new DataInputStream(System.in);
+            DataOutputStream out = new DataOutputStream(socket.getOutputStream());
+            
+            char type = 's'; // s for string
+            int length = 29;
+            String data = "This is a string of length 29";
+            byte[] dataInBytes = data.getBytes(StandardCharsets.UTF_8);         
+            //Sending data in TLV format        
+            out.writeChar(type);
+            out.writeInt(length);
+            out.write(dataInBytes);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

core-java-networking/src/main/java/com/baeldung/socket/read/Server.java

@@ -0,0 +1,49 @@
+package com.baeldung.socket.read;
+
+import java.net.*;
+import java.nio.charset.StandardCharsets;
+import java.io.*; 
+
+public class Server {
+    
+    public void runServer(int port) {
+        //Start the server and wait for connection
+        try {
+            ServerSocket server = new ServerSocket(port);
+            System.out.println("Server Started. Waiting for connection ...");
+            Socket socket = server.accept();
+            System.out.println("Got connection from client.");
+            //Get input stream from socket variable and convert the same to DataInputStream
+            DataInputStream in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
+            //Read type and length of data
+            char dataType = in.readChar();
+            int length = in.readInt();
+            System.out.println("Type : "+dataType);
+            System.out.println("Lenght :"+length);
+            if(dataType == 's') {
+                //Read String data in bytes
+                byte[] messageByte = new byte[length];
+                boolean end = false;
+                StringBuilder dataString = new StringBuilder(length);
+                int totalBytesRead = 0;
+                //We need to run while loop, to read all data in that stream
+                while(!end) {
+                    int currentBytesRead = in.read(messageByte);
+                    totalBytesRead = currentBytesRead + totalBytesRead;
+                    if(totalBytesRead <= length) {
+                        dataString.append(new String(messageByte,0,currentBytesRead,StandardCharsets.UTF_8));
+                    } else {
+                        dataString.append(new String(messageByte,0,length - totalBytesRead + currentBytesRead,StandardCharsets.UTF_8));
+                    }
+                    if(dataString.length()>=length) {
+                        end = true;
+                    }
+                }
+                System.out.println("Read "+length+" bytes of message from client. Message = "+dataString);
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+}

core-java-networking/src/test/java/com/baeldung/socket/read/SocketReadAllDataLiveTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.socket.read;
+
+import java.util.concurrent.TimeUnit;
+import org.junit.jupiter.api.Test;
+
+public class SocketReadAllDataLiveTest {
+    
+    @Test
+    public void givenServerAndClient_whenClientSendsAndServerReceivesData_thenCorrect() {
+        //Run server in new thread
+        Runnable runnable1 = () -> { runServer(); };
+        Thread thread1 = new Thread(runnable1);
+        thread1.start();
+        //Wait for 10 seconds 
+        try {
+            TimeUnit.SECONDS.sleep(10);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        //Run client in a new thread
+        Runnable runnable2 = () -> { runClient(); };
+        Thread thread2 = new Thread(runnable2);
+        thread2.start();
+    }
+    
+    public static void runServer() {
+        //Run Server
+        Server server = new Server();
+        server.runServer(5555);
+    }
+    
+    public static void runClient() {
+        //Run Client
+        Client client = new Client();
+        client.runClient("127.0.0.1", 5555);
+    }
+}

core-java-os/README.md

@@ -6,3 +6,5 @@ This module uses Java 9, so make sure to have the JDK 9 installed to run it.
 ### Relevant Articles: 
 - [Java 9 Process API Improvements](http://www.baeldung.com/java-9-process-api)
 - [Guide to java.lang.Process API](https://www.baeldung.com/java-process-api)
+- [Guide to java.lang.ProcessBuilder API](https://www.baeldung.com/java-lang-processbuilder-api)
+

core-java/README.md

@@ -50,3 +50,4 @@
 - [Finding Leap Years in Java](https://www.baeldung.com/java-leap-year)
 - [Java Bitwise Operators](https://www.baeldung.com/java-bitwise-operators)
 - [Guide to Creating and Running a Jar File in Java](https://www.baeldung.com/java-create-jar)
+- [Making a JSON POST Request With HttpURLConnection](https://www.baeldung.com/httpurlconnection-post)

core-kotlin-2/README.md

@@ -2,3 +2,5 @@
 
 - [Void Type in Kotlin](https://www.baeldung.com/kotlin-void-type)
 - [How to use Kotlin Range Expressions](https://www.baeldung.com/kotlin-ranges)
+- [Split a List into Parts in Kotlin](https://www.baeldung.com/kotlin-split-list-into-parts)
+- [String Comparison in Kotlin](https://www.baeldung.com/kotlin-string-comparison)

core-kotlin-2/pom.xml

@@ -13,4 +13,66 @@
         <relativePath>../parent-kotlin</relativePath>
     </parent>
 
-</project>
+    <dependencies>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib-jdk8</artifactId>
+            <version>${kotlin.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-runner</artifactId>
+            <version>${junit.platform.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-test</artifactId>
+            <version>${kotlin.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.jetbrains.kotlin</groupId>
+                <artifactId>kotlin-maven-plugin</artifactId>
+                <version>${kotlin.version}</version>
+                <executions>
+                    <execution>
+                        <id>compile</id>
+                        <phase>compile</phase>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                    </execution>
+                    <execution>
+                        <id>test-compile</id>
+                        <phase>test-compile</phase>
+                        <goals>
+                            <goal>test-compile</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                    <jvmTarget>1.8</jvmTarget>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <kotlin.version>1.2.71</kotlin.version>
+        <junit.platform.version>1.1.1</junit.platform.version>
+        <junit.vintage.version>5.2.0</junit.vintage.version>
+        <assertj.version>3.10.0</assertj.version>
+    </properties>
+
+</project>

core-kotlin-2/src/main/kotlin/com/baeldung/annotations/Annotations.kt

@@ -0,0 +1,7 @@
+package com.baeldung.annotations
+
+@Target(AnnotationTarget.FIELD)
+annotation class Positive
+
+@Target(AnnotationTarget.FIELD)
+annotation class AllowedNames(val names: Array<String>)

core-kotlin-2/src/main/kotlin/com/baeldung/annotations/Item.kt

@@ -0,0 +1,3 @@
+package com.baeldung.annotations
+
+class Item(@Positive val amount: Float, @AllowedNames(["Alice", "Bob"]) val name: String)

core-kotlin-2/src/main/kotlin/com/baeldung/annotations/Main.kt

@@ -0,0 +1,7 @@
+package com.baeldung.annotations
+
+fun main(args: Array<String>) {
+    val item = Item(amount = 1.0f, name = "Bob")
+    val validator = Validator()
+    println("Is instance valid? ${validator.isValid(item)}")
+}

core-kotlin-2/src/main/kotlin/com/baeldung/annotations/Validator.kt

@@ -0,0 +1,38 @@
+package com.baeldung.annotations
+
+/**
+ * Naive annotation-based validator.
+ * @author A.Shcherbakov
+ */
+class Validator() {
+
+    /**
+     * Return true if every item's property annotated with @Positive is positive and if
+     * every item's property annotated with @AllowedNames has a value specified in that annotation.
+     */
+    fun isValid(item: Item): Boolean {
+        val fields = item::class.java.declaredFields
+        for (field in fields) {
+            field.isAccessible = true
+            for (annotation in field.annotations) {
+                val value = field.get(item)
+                if (field.isAnnotationPresent(Positive::class.java)) {
+                    val amount = value as Float
+                    if (amount < 0) {
+                        return false
+                    }
+                }
+                if (field.isAnnotationPresent(AllowedNames::class.java)) {
+                    val allowedNames = field.getAnnotation(AllowedNames::class.java)?.names
+                    val name = value as String
+                    allowedNames?.let {
+                        if (!it.contains(name)) {
+                            return false
+                        }
+                    }
+                }
+            }
+        }
+        return true
+    }
+}

core-kotlin-2/src/main/kotlin/com/baeldung/range/CharRange.kt

@@ -0,0 +1,13 @@
+package com.baeldung.range
+
+fun main(args: Array<String>) {
+
+    for (ch in 'a'..'f') {
+        print(ch)
+    }
+    println()
+
+    for (ch in 'f' downTo 'a') {
+        print(ch)
+    }
+}

core-kotlin-2/src/main/kotlin/com/baeldung/range/Color.kt

@@ -0,0 +1,21 @@
+package com.baeldung.range
+
+enum class Color(val rgb: Int) {
+    BLUE(0x0000FF),
+    GREEN(0x008000),
+    RED(0xFF0000),
+    MAGENTA(0xFF00FF),
+    YELLOW(0xFFFF00);
+}
+
+fun main(args: Array<String>) {
+
+    println(Color.values().toList());
+    val red = Color.RED
+    val yellow = Color.YELLOW
+    val range = red..yellow
+
+    println(range.contains(Color.MAGENTA))
+    println(range.contains(Color.BLUE))
+    println(range.contains(Color.GREEN))
+}

core-kotlin-2/src/main/kotlin/com/baeldung/range/Filter.kt

@@ -0,0 +1,18 @@
+package com.baeldung.range
+
+fun main(args: Array<String>) {
+    val r = 1..10
+
+    //Apply filter
+    val f = r.filter { it -> it % 2 == 0 }
+    println(f)
+
+    //Map
+    val m = r.map { it -> it * it }
+    println(m)
+
+    //Reduce
+    val rdc = r.reduce { a, b -> a + b }
+    println(rdc)
+
+}

core-kotlin-2/src/main/kotlin/com/baeldung/range/FirstLast.kt

@@ -0,0 +1,8 @@
+package com.baeldung.range
+
+fun main(args: Array<String>) {
+
+    println((1..9).first)
+    println((1..9 step 2).step)
+    println((3..9).reversed().last)
+}

core-kotlin-2/src/main/kotlin/com/baeldung/range/OtherRangeFunctions.kt

@@ -0,0 +1,14 @@
+package com.baeldung.range
+
+fun main(args: Array<String>) {
+
+    val r = 1..20
+    println(r.min())
+    println(r.max())
+    println(r.sum())
+    println(r.average())
+    println(r.count())
+
+    val repeated = listOf(1, 1, 2, 4, 4, 6, 10)
+    println(repeated.distinct())
+}

core-kotlin-2/src/main/kotlin/com/baeldung/range/Range.kt

@@ -0,0 +1,28 @@
+package com.baeldung.range
+
+fun main(args: Array<String>) {
+
+    for (i in 1..9) {
+        print(i)
+    }
+    println()
+
+    for (i in 9 downTo 1) {
+        print(i)
+    }
+    println()
+
+    for (i in 1.rangeTo(9)) {
+        print(i)
+    }
+    println()
+
+    for (i in 9.downTo(1)) {
+        print(i)
+    }
+    println()
+
+    for (i in 1 until 9) {
+        print(i)
+    }
+}

core-kotlin-2/src/main/kotlin/com/baeldung/range/ReverseRange.kt

@@ -0,0 +1,14 @@
+package com.baeldung.range
+
+fun main(args: Array<String>) {
+
+    (1..9).reversed().forEach {
+        print(it)
+    }
+
+    println()
+
+    (1..9).reversed().step(3).forEach {
+        print(it)
+    }
+}

core-kotlin-2/src/main/kotlin/com/baeldung/range/Step.kt

@@ -0,0 +1,15 @@
+package com.baeldung.range
+
+fun main(args: Array<String>) {
+
+    for(i in 1..9 step 2){
+        print(i)
+    }
+
+    println()
+
+    for (i in 9 downTo 1 step 2){
+        print(i)
+    }
+
+}

core-kotlin-2/src/main/kotlin/com/baeldung/range/UntilRange.kt

@@ -0,0 +1,8 @@
+package com.baeldung.range
+
+fun main(args: Array<String>) {
+
+    for (i in 1 until 9) {
+        print(i)
+    }
+}

core-kotlin-2/src/main/kotlin/com/baeldung/scope/ScopeFunctions.kt

@@ -0,0 +1,25 @@
+package com.baeldung.scope
+
+data class Student(var studentId: String = "", var name: String = "", var surname: String = "") {
+}
+
+data class Teacher(var teacherId: Int = 0, var name: String = "", var surname: String = "") {
+    fun setId(anId: Int): Teacher = apply { teacherId = anId }
+    fun setName(aName: String): Teacher = apply { name = aName }
+    fun setSurname(aSurname: String): Teacher = apply { surname = aSurname }
+}
+
+data class Headers(val headerInfo: String)
+
+data class Response(val headers: Headers)
+
+data class RestClient(val url: String) {
+    fun getResponse() = Response(Headers("some header info"))
+}
+
+data class BankAccount(val id: Int) {
+    fun checkAuthorization(username: String) = Unit
+    fun addPayee(payee: String) = Unit
+    fun makePayment(paymentDetails: String) = Unit
+
+}

core-kotlin-2/src/test/kotlin/com/baeldung/annotations/ValidationTest.kt

@@ -0,0 +1,41 @@
+package com.baeldung.annotations
+
+import org.junit.Test
+import kotlin.test.assertTrue
+import kotlin.test.assertFalse
+
+class ValidationTest {
+
+    @Test
+    fun whenAmountIsOneAndNameIsAlice_thenTrue() {
+        assertTrue(Validator().isValid(Item(1f, "Alice")))
+    }
+
+    @Test
+    fun whenAmountIsOneAndNameIsBob_thenTrue() {
+        assertTrue(Validator().isValid(Item(1f, "Bob")))
+    }
+
+
+    @Test
+    fun whenAmountIsMinusOneAndNameIsAlice_thenFalse() {
+        assertFalse(Validator().isValid(Item(-1f, "Alice")))
+    }
+
+    @Test
+    fun whenAmountIsMinusOneAndNameIsBob_thenFalse() {
+        assertFalse(Validator().isValid(Item(-1f, "Bob")))
+    }
+
+    @Test
+    fun whenAmountIsOneAndNameIsTom_thenFalse() {
+        assertFalse(Validator().isValid(Item(1f, "Tom")))
+    }
+
+    @Test
+    fun whenAmountIsMinusOneAndNameIsTom_thenFalse() {
+        assertFalse(Validator().isValid(Item(-1f, "Tom")))
+    }
+
+
+}

core-kotlin-2/src/test/kotlin/com/baeldung/range/CharRangeTest.kt

@@ -0,0 +1,17 @@
+package com.baeldung.range
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class CharRangeTest {
+
+    @Test
+    fun testCharRange() {
+        assertEquals(listOf('a', 'b', 'c'), ('a'..'c').toList())
+    }
+
+    @Test
+    fun testCharDownRange() {
+        assertEquals(listOf('c', 'b', 'a'), ('c'.downTo('a')).toList())
+    }
+}

core-kotlin-2/src/test/kotlin/com/baeldung/range/ColorTest.kt

@@ -0,0 +1,20 @@
+package com.baeldung.range
+
+import org.junit.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class ColorTest {
+
+    @Test
+    fun testEnumRange() {
+
+        println(Color.values().toList());
+        val red = Color.RED
+        val yellow = Color.YELLOW
+        val range = red..yellow
+
+        assertTrue { range.contains(Color.MAGENTA) }
+        assertFalse { range.contains(Color.BLUE) }
+    }
+}

core-kotlin-2/src/test/kotlin/com/baeldung/range/FilterTest.kt

@@ -0,0 +1,24 @@
+package com.baeldung.range
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class FilterTest {
+
+    val r = 1..10
+
+    @Test
+    fun filterTest() {
+        assertEquals(listOf(2, 4, 6, 8, 10), r.filter { it -> it % 2 == 0 }.toList())
+    }
+
+    @Test
+    fun mapTest() {
+        assertEquals(listOf(1, 4, 9, 16, 25, 36, 49, 64, 81, 100), r.map { it -> it * it }.toList())
+    }
+
+    @Test
+    fun reduceTest() {
+        assertEquals(55, r.reduce { a, b -> a + b })
+    }
+}

core-kotlin-2/src/test/kotlin/com/baeldung/range/FirstLastTest.kt

@@ -0,0 +1,22 @@
+package com.baeldung.range
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class FirstLastTest {
+
+    @Test
+    fun testFirst() {
+        assertEquals(1, (1..9).first)
+    }
+
+    @Test
+    fun testLast() {
+        assertEquals(9, (1..9).last)
+    }
+
+    @Test
+    fun testStep() {
+        assertEquals(2, (1..9 step 2).step)
+    }
+}

core-kotlin-2/src/test/kotlin/com/baeldung/range/OtherRangeFunctionsTest.kt

@@ -0,0 +1,40 @@
+package com.baeldung.range
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class OtherRangeFunctionsTest {
+
+    val r = 1..20
+    val repeated = listOf(1, 1, 2, 4, 4, 6, 10)
+
+    @Test
+    fun testMin() {
+        assertEquals(1, r.min())
+    }
+
+    @Test
+    fun testMax() {
+        assertEquals(20, r.max())
+    }
+
+    @Test
+    fun testSum() {
+        assertEquals(210, r.sum())
+    }
+
+    @Test
+    fun testAverage() {
+        assertEquals(10.5, r.average())
+    }
+
+    @Test
+    fun testCount() {
+        assertEquals(20, r.count())
+    }
+
+    @Test
+    fun testDistinct() {
+        assertEquals(listOf(1, 2, 4, 6, 10), repeated.distinct())
+    }
+}

core-kotlin-2/src/test/kotlin/com/baeldung/range/RangeTest.kt

@@ -0,0 +1,22 @@
+package com.baeldung.range
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class RangeTest {
+
+    @Test
+    fun testRange() {
+        assertEquals(listOf(1,2,3), (1.rangeTo(3).toList()))
+    }
+
+    @Test
+    fun testDownTo(){
+        assertEquals(listOf(3,2,1), (3.downTo(1).toList()))
+    }
+
+    @Test
+    fun testUntil(){
+        assertEquals(listOf(1,2), (1.until(3).toList()))
+    }
+}

core-kotlin-2/src/test/kotlin/com/baeldung/range/ReverseRangeTest.kt

@@ -0,0 +1,12 @@
+package com.baeldung.range
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class ReverseRangeTest {
+
+    @Test
+    fun reversedTest() {
+        assertEquals(listOf(9, 6, 3), (1..9).reversed().step(3).toList())
+    }
+}

core-kotlin-2/src/test/kotlin/com/baeldung/range/StepTest.kt

@@ -0,0 +1,17 @@
+package com.baeldung.range
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class StepTest {
+
+    @Test
+    fun testStep() {
+        assertEquals(listOf(1, 3, 5, 7, 9), (1..9 step 2).toList())
+    }
+
+    @Test
+    fun testStepDown() {
+        assertEquals(listOf(9, 7, 5, 3, 1), (9 downTo 1 step 2).toList())
+    }
+}

core-kotlin-2/src/test/kotlin/com/baeldung/range/UntilRangeTest.kt

@@ -0,0 +1,12 @@
+package com.baeldung.range
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class UntilRangeTest {
+
+    @Test
+    fun testUntil() {
+        assertEquals(listOf(1, 2, 3, 4), (1 until 5).toList())
+    }
+}

core-kotlin-2/src/test/kotlin/com/baeldung/scope/ScopeFunctionsUnitTest.kt

@@ -0,0 +1,143 @@
+package com.baeldung.scope
+
+import org.junit.Test
+import kotlin.test.assertTrue
+
+
+class ScopeFunctionsUnitTest {
+
+    class Logger {
+
+        var called : Boolean = false
+
+        fun info(message: String) {
+            called = true
+        }
+
+        fun wasCalled() = called
+    }
+
+    @Test
+    fun shouldTransformWhenLetFunctionUsed() {
+        val stringBuider = StringBuilder()
+        val numberOfCharacters = stringBuider.let {
+            it.append("This is a transformation function.")
+            it.append("It takes a StringBuilder instance and returns the number of characters in the generated String")
+            it.length
+        }
+
+        assertTrue {
+            numberOfCharacters == 128
+        }
+    }
+
+    @Test
+    fun shouldHandleNullabilityWhenLetFunctionUsed() {
+
+        val message: String? = "hello there!"
+        val charactersInMessage = message?.let {
+            "At this point is safe to reference the variable. Let's print the message: $it"
+        } ?: "default value"
+
+        assertTrue {
+            charactersInMessage.equals("At this point is safe to reference the variable. Let's print the message: hello there!")
+        }
+
+        val aNullMessage = null
+        val thisIsNull = aNullMessage?.let {
+            "At this point it would be safe to reference the variable. But it will not really happen because it is null. Let's reference: $it"
+        } ?: "default value"
+
+        assertTrue {
+            thisIsNull.equals("default value")
+        }
+    }
+
+    @Test
+    fun shouldInitializeObjectWhenUsingApply() {
+        val aStudent = Student().apply {
+            studentId = "1234567"
+            name = "Mary"
+            surname = "Smith"
+        }
+
+        assertTrue {
+            aStudent.name.equals("Mary")
+        }
+    }
+
+    @Test
+    fun shouldAllowBuilderStyleObjectDesignWhenApplyUsedInClassMethods() {
+        val teacher = Teacher()
+            .setId(1000)
+            .setName("Martha")
+            .setSurname("Spector")
+
+        assertTrue {
+            teacher.surname.equals("Spector")
+        }
+    }
+
+    @Test
+    fun shouldAllowSideEffectWhenUsingAlso() {
+        val restClient = RestClient("http://www.someurl.com")
+
+        val logger = Logger()
+
+        val headers = restClient
+            .getResponse()
+            .also { logger.info(it.toString()) }
+            .headers
+
+        assertTrue {
+            logger.wasCalled() && headers.headerInfo.equals("some header info")
+        }
+
+    }
+
+    @Test
+    fun shouldInitializeFieldWhenAlsoUsed() {
+        val aStudent = Student().also { it.name = "John"}
+
+        assertTrue {
+            aStudent.name.equals("John")
+        }
+    }
+
+    @Test
+    fun shouldLogicallyGroupObjectCallsWhenUsingWith() {
+        val bankAccount = BankAccount(1000)
+        with (bankAccount) {
+            checkAuthorization("someone")
+            addPayee("some payee")
+            makePayment("payment information")
+        }
+    }
+
+    @Test
+    fun shouldConvertObjectWhenRunUsed() {
+        val stringBuider = StringBuilder()
+        val numberOfCharacters = stringBuider.run {
+            append("This is a transformation function.")
+            append("It takes a StringBuilder instance and returns the number of characters in the generated String")
+            length
+        }
+
+        assertTrue {
+            numberOfCharacters == 128
+        }
+    }
+
+    @Test
+    fun shouldHandleNullabilityWhenRunIsUsed() {
+        val message: String? = "hello there!"
+        val charactersInMessage = message?.run {
+            "At this point is safe to reference the variable. Let's print the message: $this"
+        } ?: "default value"
+
+        assertTrue {
+            charactersInMessage.equals("At this point is safe to reference the variable. Let's print the message: hello there!")
+        }
+    }
+
+}

core-kotlin/README.md

@@ -55,3 +55,4 @@
 - [Building DSLs in Kotlin](https://www.baeldung.com/kotlin-dsl)
 - [Static Methods Behavior in Kotlin](https://www.baeldung.com/kotlin-static-methods)
 - [Inline Functions in Kotlin](https://www.baeldung.com/kotlin-inline-functions)
+- [Delegation Pattern in Kotlin](https://www.baeldung.com/kotlin-delegation-pattern)

gson/README.md

@@ -11,3 +11,6 @@
 - [Convert JSON to a Map Using Gson](https://www.baeldung.com/gson-json-to-map)
 - [Working with Primitive Values in Gson](https://www.baeldung.com/java-gson-primitives)
 - [Convert String to JsonObject with Gson](https://www.baeldung.com/gson-string-to-jsonobject)
+- [Mapping Multiple JSON Fields to One Java Field](https://www.baeldung.com/json-multiple-fields-single-java-field)
+- [Serializing and Deserializing a List with Gson](https://www.baeldung.com/gson-list)
+

jackson-2/.gitignore

@@ -0,0 +1,13 @@
+*.class
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+
+# Packaged files #
+*.jar
+*.war
+*.ear

jackson-2/README.md

@@ -0,0 +1,9 @@
+=========
+
+## Jackson Cookbooks and Examples
+
+###The Course
+The "REST With Spring" Classes: http://bit.ly/restwithspring
+
+### Relevant Articles: 
+- [Mapping Multiple JSON Fields to a Single Java Field](https://www.baeldung.com/json-multiple-fields-single-java-field)

jackson-2/pom.xml

@@ -0,0 +1,52 @@
+<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>jackson-2</artifactId>
+    <version>0.1-SNAPSHOT</version>
+    <name>jackson-2</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+
+        <!-- marshalling -->
+
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+
+
+        <!-- test scoped -->
+
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>jackson-2</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+
+        <!-- testing -->
+        <assertj.version>3.11.0</assertj.version>
+    </properties>
+
+</project>

jackson-2/src/main/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

java-collections-maps-2/pom.xml

@@ -0,0 +1,45 @@
+<?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>java-collections-maps-2</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>java-collections-maps-2</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>
+        <dependency>
+            <groupId>org.eclipse.collections</groupId>
+            <artifactId>eclipse-collections</artifactId>
+            <version>${eclipse-collections.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>net.sf.trove4j</groupId>
+            <artifactId>trove4j</artifactId>
+            <version>3.0.2</version>
+        </dependency>
+        <dependency>
+            <groupId>it.unimi.dsi</groupId>
+            <artifactId>fastutil</artifactId>
+            <version>8.1.0</version>
+        </dependency>
+        <dependency>
+            <groupId>colt</groupId>
+            <artifactId>colt</artifactId>
+            <version>1.2.0</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <eclipse-collections.version>8.2.0</eclipse-collections.version>
+    </properties>
+
+</project>

java-collections-maps-2/src/main/java/com/baeldung/map/PrimitiveMaps.java

@@ -0,0 +1,69 @@
+package com.baeldung.map;
+
+import cern.colt.map.AbstractIntDoubleMap;
+import cern.colt.map.OpenIntDoubleHashMap;
+import gnu.trove.map.TDoubleIntMap;
+import gnu.trove.map.hash.TDoubleIntHashMap;
+import it.unimi.dsi.fastutil.ints.Int2BooleanMap;
+import it.unimi.dsi.fastutil.ints.Int2BooleanOpenHashMap;
+import it.unimi.dsi.fastutil.ints.Int2BooleanSortedMap;
+import it.unimi.dsi.fastutil.ints.Int2BooleanSortedMaps;
+import org.eclipse.collections.api.map.primitive.ImmutableIntIntMap;
+import org.eclipse.collections.api.map.primitive.MutableIntIntMap;
+import org.eclipse.collections.api.map.primitive.MutableObjectDoubleMap;
+import org.eclipse.collections.impl.factory.primitive.IntIntMaps;
+import org.eclipse.collections.impl.factory.primitive.ObjectDoubleMaps;
+
+public class PrimitiveMaps {
+
+    public static void main(String[] args) {
+
+        eclipseCollectionsMap();
+        troveMap();
+        coltMap();
+        fastutilMap();
+    }
+
+    private static void fastutilMap() {
+        Int2BooleanMap int2BooleanMap = new Int2BooleanOpenHashMap();
+        int2BooleanMap.put(1, true);
+        int2BooleanMap.put(7, false);
+        int2BooleanMap.put(4, true);
+
+        boolean value = int2BooleanMap.get(1);
+
+        Int2BooleanSortedMap int2BooleanSorted = Int2BooleanSortedMaps.EMPTY_MAP;
+    }
+
+    private static void coltMap() {
+        AbstractIntDoubleMap map = new OpenIntDoubleHashMap();
+        map.put(1, 4.5);
+        double value = map.get(1);
+    }
+
+    private static void eclipseCollectionsMap() {
+        MutableIntIntMap mutableIntIntMap = IntIntMaps.mutable.empty();
+        mutableIntIntMap.addToValue(1, 1);
+
+        ImmutableIntIntMap immutableIntIntMap = IntIntMaps.immutable.empty();
+
+        MutableObjectDoubleMap<String> dObject = ObjectDoubleMaps.mutable.empty();
+        dObject.addToValue("price", 150.5);
+        dObject.addToValue("quality", 4.4);
+        dObject.addToValue("stability", 0.8);
+    }
+
+    private static void troveMap() {
+        double[] doubles = new double[] {1.2, 4.5, 0.3};
+        int[] ints = new int[] {1, 4, 0};
+
+        TDoubleIntMap doubleIntMap = new TDoubleIntHashMap(doubles, ints);
+
+        doubleIntMap.put(1.2, 22);
+        doubleIntMap.put(4.5, 16);
+
+        doubleIntMap.adjustValue(1.2, 1);
+        doubleIntMap.adjustValue(4.5, 4);
+        doubleIntMap.adjustValue(0.3, 7);
+    }
+}

java-dates-2/.gitignore

@@ -0,0 +1,29 @@
+*.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
+
+#jenv
+.java-version

java-dates-2/pom.xml

@@ -0,0 +1,55 @@
+<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-dates-2</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>java-dates-2</name>
+
+    <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>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>java-dates-2</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <maven.compiler.source>1.9</maven.compiler.source>
+        <maven.compiler.target>1.9</maven.compiler.target>
+    </properties>
+</project>

java-dates-2/src/test/java/com/baeldung/xmlgregoriancalendar/XmlGregorianCalendarConverterUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.xmlgregoriancalendar;
+
+import org.junit.Test;
+
+import javax.xml.datatype.DatatypeConfigurationException;
+import javax.xml.datatype.DatatypeConstants;
+import javax.xml.datatype.DatatypeFactory;
+import javax.xml.datatype.XMLGregorianCalendar;
+import java.time.LocalDate;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class XmlGregorianCalendarConverterUnitTest {
+
+    @Test
+    public void fromLocalDateToXMLGregorianCalendar() throws DatatypeConfigurationException {
+        LocalDate localDate = LocalDate.of(2017, 4, 25);
+        XMLGregorianCalendar xmlGregorianCalendar = DatatypeFactory.newInstance().newXMLGregorianCalendar(localDate.toString());
+
+        assertThat(xmlGregorianCalendar.getYear()).isEqualTo(localDate.getYear());
+        assertThat(xmlGregorianCalendar.getMonth()).isEqualTo(localDate.getMonthValue());
+        assertThat(xmlGregorianCalendar.getDay()).isEqualTo(localDate.getDayOfMonth());
+        assertThat(xmlGregorianCalendar.getTimezone()).isEqualTo(DatatypeConstants.FIELD_UNDEFINED);
+    }
+
+    @Test
+    public void fromXMLGregorianCalendarToLocalDate() throws DatatypeConfigurationException {
+        XMLGregorianCalendar xmlGregorianCalendar = DatatypeFactory.newInstance().newXMLGregorianCalendar("2017-04-25");
+        LocalDate localDate = LocalDate.of(xmlGregorianCalendar.getYear(), xmlGregorianCalendar.getMonth(), xmlGregorianCalendar.getDay());
+
+        assertThat(localDate.getYear()).isEqualTo(xmlGregorianCalendar.getYear());
+        assertThat(localDate.getMonthValue()).isEqualTo(xmlGregorianCalendar.getMonth());
+        assertThat(localDate.getDayOfMonth()).isEqualTo(xmlGregorianCalendar.getDay());
+    }
+
+}

java-streams-2/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+- [Guide to Stream.reduce()](https://www.baeldung.com/java-stream-reduce)
+

java-streams/README.md

@@ -17,3 +17,4 @@
 - [Java Stream Filter with Lambda Expression](https://www.baeldung.com/java-stream-filter-lambda)
 - [Counting Matches on a Stream Filter](https://www.baeldung.com/java-stream-filter-count)
 - [Java 8 Streams peek() API](https://www.baeldung.com/java-streams-peek-api)
+- [Working With Maps Using Streams](https://www.baeldung.com/java-maps-streams)

javax-servlets/src/main/java/com/baeldung/filters/EmptyParamFilter.java

@@ -0,0 +1,35 @@
+package com.baeldung.filters;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.annotation.WebFilter;
+import java.io.IOException;
+
+@WebFilter(urlPatterns = "/uppercase")
+public class EmptyParamFilter implements Filter {
+
+    @Override
+    public void init(FilterConfig filterConfig) throws ServletException {
+    }
+
+    @Override
+    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
+        FilterChain filterChain) throws IOException, ServletException {
+        String inputString = servletRequest.getParameter("input");
+
+        if (inputString != null && inputString.matches("[A-Za-z0-9]+")) {
+            filterChain.doFilter(servletRequest, servletResponse);
+        } else {
+            servletResponse.getWriter().println("Missing input parameter");
+        }
+    }
+
+    @Override
+    public void destroy() {
+    }
+
+}

javax-servlets/src/main/java/com/baeldung/listeners/AppListener.java

@@ -0,0 +1,21 @@
+package com.baeldung.listeners;
+
+import javax.servlet.ServletContext;
+import javax.servlet.ServletContextEvent;
+import javax.servlet.ServletContextListener;
+import javax.servlet.annotation.WebListener;
+
+@WebListener
+public class AppListener implements ServletContextListener {
+
+    @Override
+    public void contextInitialized(ServletContextEvent event) {
+        ServletContext context = event.getServletContext();
+        context.setAttribute("counter", 0);
+    }
+
+    @Override
+    public void contextDestroyed(ServletContextEvent event) {
+
+    }
+}

javax-servlets/src/main/java/com/baeldung/listeners/RequestListener.java

@@ -0,0 +1,24 @@
+package com.baeldung.listeners;
+
+import javax.servlet.ServletContext;
+import javax.servlet.ServletRequestEvent;
+import javax.servlet.ServletRequestListener;
+import javax.servlet.annotation.WebListener;
+import javax.servlet.http.HttpServletRequest;
+
+@WebListener
+public class RequestListener implements ServletRequestListener {
+
+    @Override
+    public void requestInitialized(ServletRequestEvent event) {
+    }
+
+    @Override
+    public void requestDestroyed(ServletRequestEvent event) {
+        HttpServletRequest request = (HttpServletRequest)event.getServletRequest();
+        if (!request.getServletPath().equals("/counter")) {
+            ServletContext context = event.getServletContext();
+            context.setAttribute("counter", (int)context.getAttribute("counter") + 1);
+        }
+    }
+}

javax-servlets/src/main/java/com/baeldung/servlets/CounterServlet.java

@@ -0,0 +1,21 @@
+package com.baeldung.servlets;
+
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.io.PrintWriter;
+
+@WebServlet(urlPatterns = "/counter", name = "counterServlet")
+public class CounterServlet extends HttpServlet {
+
+    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
+        PrintWriter out = response.getWriter();
+
+        int count = (int)request.getServletContext().getAttribute("counter");
+
+        out.println("Request counter: " + count);
+    }
+
+}

javax-servlets/src/main/java/com/baeldung/servlets/UppercaseServlet.java

@@ -0,0 +1,20 @@
+package com.baeldung.servlets;
+
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.io.PrintWriter;
+
+@WebServlet(urlPatterns = "/uppercase", name = "uppercaseServlet")
+public class UppercaseServlet extends HttpServlet {
+
+    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
+        String inputString = request.getParameter("input").toUpperCase();
+
+        PrintWriter out = response.getWriter();
+
+        out.println(inputString);
+    }
+}

kotlin-libraries/pom.xml

@@ -19,6 +19,14 @@
             <name>exposed</name>
             <url>https://dl.bintray.com/kotlin/exposed</url>
         </repository>
+        <repository>
+            <snapshots>
+                <enabled>false</enabled>
+            </snapshots>
+            <id>kotlinx</id>
+            <name>bintray</name>
+            <url>https://dl.bintray.com/kotlin/kotlinx</url>
+        </repository>
     </repositories>
 
     <dependencies>
@@ -112,9 +120,30 @@
             <version>3.3.0</version>
             <type>pom</type>
         </dependency>
+
+        <!-- https://mvnrepository.com/artifact/junit/junit -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>27.1-jre</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.jetbrains.kotlinx/kotlinx-collections-immutable -->
+        <dependency>
+            <groupId>org.jetbrains.kotlinx</groupId>
+            <artifactId>kotlinx-collections-immutable</artifactId>
+            <version>0.1</version>
+        </dependency>
     </dependencies>
 
     <properties>
+        <junit.version>4.12</junit.version>
         <mockito-kotlin.version>1.5.0</mockito-kotlin.version>
         <kodein.version>4.1.0</kodein.version>
         <klaxon.version>3.0.4</klaxon.version>

kotlin-libraries/src/test/kotlin/com/baeldung/kotlin/immutable/KotlinxImmutablesUnitTest.kt

@@ -0,0 +1,27 @@
+package com.baeldung.kotlin.immutable
+
+import junit.framework.Assert.assertEquals
+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.immutableListOf
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.ExpectedException
+
+class KotlinxImmutablesUnitTest{
+
+
+  @Rule
+  @JvmField
+  var ee : ExpectedException = ExpectedException.none()
+
+  @Test
+  fun givenKICLList_whenAddTried_checkExceptionThrown(){
+
+      val list: ImmutableList<String> = immutableListOf("I", "am", "immutable")
+
+      list.add("My new item")
+
+      assertEquals(listOf("I", "am", "immutable"), list)
+
+  }
+}

kotlin-libraries/src/test/kotlin/com/baeldung/kotlin/immutable/ReadOnlyUnitTest.kt

@@ -0,0 +1,73 @@
+package com.baeldung.kotlin.immutable
+
+import com.google.common.collect.ImmutableList
+import com.google.common.collect.ImmutableSet
+import junit.framework.Assert.assertEquals
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.ExpectedException
+
+class ReadOnlyUnitTest{
+
+    @Test
+    fun givenReadOnlyList_whenCastToMutableList_checkNewElementsAdded(){
+
+        val list: List<String> = listOf("This", "Is", "Totally", "Immutable")
+
+        (list as MutableList<String>)[2] = "Not"
+
+        assertEquals(listOf("This", "Is", "Not", "Immutable"), list)
+
+    }
+
+    @Rule
+    @JvmField
+    var ee : ExpectedException = ExpectedException.none()
+
+    @Test
+    fun givenImmutableList_whenAddTried_checkExceptionThrown(){
+
+        val list: List<String> = ImmutableList.of("I", "am", "actually", "immutable")
+
+        ee.expect(UnsupportedOperationException::class.java)
+
+        (list as MutableList<String>).add("Oops")
+
+    }
+
+    @Test
+    fun givenMutableList_whenCopiedAndAddTried_checkExceptionThrown(){
+
+        val mutableList : List<String> = listOf("I", "Am", "Definitely", "Immutable")
+
+        (mutableList as MutableList<String>)[2] = "100% Not"
+
+        assertEquals(listOf("I", "Am", "100% Not", "Immutable"), mutableList)
+
+        val list: List<String> = ImmutableList.copyOf(mutableList)
+
+        ee.expect(UnsupportedOperationException::class.java)
+
+        (list as MutableList<String>)[2] = "Really?"
+
+    }
+
+    @Test
+    fun givenImmutableSetBuilder_whenAddTried_checkExceptionThrown(){
+
+        val mutableList : List<String> = listOf("Hello", "Baeldung")
+        val set: ImmutableSet<String> = ImmutableSet.builder<String>()
+                .add("I","am","immutable")
+                .addAll(mutableList)
+                .build()
+
+        assertEquals(setOf("Hello", "Baeldung", "I", "am", "immutable"), set)
+
+        ee.expect(UnsupportedOperationException::class.java)
+
+        (set as MutableSet<String>).add("Oops")
+
+    }
+
+
+}

lombok/README.md

@@ -6,4 +6,5 @@
 - [Lombok Builder with Default Value](https://www.baeldung.com/lombok-builder-default-value)
 - [Lombok Builder with Custom Setter](https://www.baeldung.com/lombok-builder-custom-setter)
 - [Setting up Lombok with Eclipse and Intellij](https://www.baeldung.com/lombok-ide)
+- [Using the @Singular Annotation with Lombok Builders](https://www.baeldung.com/lombok-builder-singular)
 

lombok/src/main/java/com/baeldung/lombok/builder/singular/Person.java

@@ -0,0 +1,25 @@
+package com.baeldung.lombok.builder.singular;
+
+import lombok.Builder;
+import lombok.Getter;
+import lombok.Singular;
+
+import java.time.LocalDate;
+import java.util.Date;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+@Getter
+@Builder
+public class Person {
+
+    private final String givenName;
+    private final String additionalName;
+    private final String familyName;
+
+    private final List<String> tags;
+    @Singular private final List<String> interests;
+    @Singular private final Set<String> skills;
+    @Singular private final Map<String, LocalDate> awards;
+}

lombok/src/main/java/com/baeldung/lombok/builder/singular/Sea.java

@@ -0,0 +1,14 @@
+package com.baeldung.lombok.builder.singular;
+
+import java.util.List;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.Singular;
+
+@Getter
+@Builder
+public class Sea {
+
+    @Singular private final List<String> grasses;
+    @Singular("oneFish") private final List<String> fish;
+}

lombok/src/test/java/com/baeldung/lombok/builder/singular/BuilderWithSingularSupportForCollectionsUnitTest.java

@@ -0,0 +1,192 @@
+package com.baeldung.lombok.builder.singular;
+
+import org.junit.Test;
+
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.*;
+
+public class BuilderWithSingularSupportForCollectionsUnitTest {
+
+    @Test
+    public void canAddMultipleElementsAsNewCollection() throws Exception {
+        Person person = Person.builder()
+            .givenName("Aaron")
+            .additionalName("A")
+            .familyName("Aardvark")
+            .tags(Arrays.asList("fictional", "incidental"))
+            .build();
+
+        assertThat(person.getTags(), containsInAnyOrder("fictional", "incidental"));
+    }
+
+    @Test
+    public void canUpdateCollectionAfterBuildIfMutableCollectionPassedToBuilder() throws Exception {
+
+        List<String> tags = new ArrayList();
+        tags.add("fictional");
+        tags.add("incidental");
+        Person person = Person.builder()
+            .givenName("Aaron")
+            .additionalName("A")
+            .familyName("Aardvark")
+            .tags(tags)
+            .build();
+        person.getTags()
+            .clear();
+        person.getTags()
+            .add("non-fictional");
+        person.getTags()
+            .add("important");
+
+        assertThat(person.getTags(), containsInAnyOrder("non-fictional", "important"));
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void cannotUpdateCollectionAfterBuildIfImmutableCollectionPassedToBuilder() throws Exception {
+        List<String> tags = Arrays.asList("fictional", "incidental");
+        Person person = Person.builder()
+            .givenName("Aaron")
+            .additionalName("A")
+            .familyName("Aardvark")
+            .tags(tags)
+            .build();
+        person.getTags()
+            .clear();
+    }
+
+    @Test
+    public void canAssignToSingularAnnotatedCollectionOneByOne() throws Exception {
+
+        Person person = Person.builder()
+            .givenName("Aaron")
+            .additionalName("A")
+            .familyName("Aardvark")
+            .interest("history")
+            .interest("sport")
+            .build();
+
+        assertThat(person.getInterests(), containsInAnyOrder("sport", "history"));
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void singularAnnotatedBuilderCreatesImmutableCollection() throws Exception {
+
+        Person person = Person.builder()
+            .givenName("Aaron")
+            .additionalName("A")
+            .familyName("Aardvark")
+            .interest("history")
+            .interest("sport")
+            .build();
+        person.getInterests()
+            .clear();
+    }
+
+    @Test
+    public void unpopulatedListsCreatedAsNullIfNotSingularButEmptyArrayIfSingular() throws Exception {
+
+        Person person = Person.builder()
+            .givenName("Aaron")
+            .additionalName("A")
+            .familyName("Aardvark")
+            .build();
+        assertThat(person.getInterests(), hasSize(0));
+        assertThat(person.getSkills(), hasSize(0));
+        assertThat(person.getAwards()
+            .keySet(), hasSize(0));
+        assertThat(person.getTags(), is(nullValue()));
+    }
+
+    @Test
+    public void singularSupportsSetsToo() throws Exception {
+
+        Person person = Person.builder()
+            .givenName("Aaron")
+            .additionalName("A")
+            .familyName("Aardvark")
+            .skill("singing")
+            .skill("dancing")
+            .build();
+        assertThat(person.getSkills(), contains("singing", "dancing"));
+    }
+
+    @Test
+    public void singularSetsAreLenientWithDuplicates() throws Exception {
+
+        Person person = Person.builder()
+            .givenName("Aaron")
+            .additionalName("A")
+            .familyName("Aardvark")
+            .interest("singing")
+            .interest("singing")
+            .skill("singing")
+            .skill("singing")
+            .build();
+        assertThat(person.getInterests(), contains("singing", "singing"));
+        assertThat(person.getSkills(), contains("singing"));
+    }
+
+    @Test
+    public void singularSupportsMapsToo() throws Exception {
+
+        Person person = Person.builder()
+            .givenName("Aaron")
+            .additionalName("A")
+            .familyName("Aardvark")
+            .award("Singer of the Year", LocalDate.now()
+                .minusYears(5))
+            .award("Best Dancer", LocalDate.now()
+                .minusYears(2))
+            .build();
+        assertThat(person.getAwards()
+            .keySet(), contains("Singer of the Year", "Best Dancer"));
+        assertThat(person.getAwards()
+            .get("Best Dancer"),
+            is(LocalDate.now()
+                .minusYears(2)));
+    }
+
+    @Test
+    public void singularIsLenientWithMapKeys() throws Exception {
+
+        Person person = Person.builder()
+            .givenName("Aaron")
+            .additionalName("A")
+            .familyName("Aardvark")
+            .award("Best Dancer", LocalDate.now()
+                .minusYears(5))
+            .award("Best Dancer", LocalDate.now()
+                .minusYears(4))
+            .award("Best Dancer", LocalDate.now()
+                .minusYears(3))
+            .award("Best Dancer", LocalDate.now()
+                .minusYears(2))
+            .award("Best Dancer", LocalDate.now()
+                .minusYears(1))
+            .build();
+        assertThat(person.getAwards()
+            .keySet(), hasSize(1));
+        assertThat(person.getAwards()
+            .get("Best Dancer"),
+            is(LocalDate.now()
+                .minusYears(1)));
+    }
+
+    @Test
+    public void wordsWithNonStandardPlurals() throws Exception {
+        Sea sea = Sea.builder()
+            .grass("Dulse")
+            .grass("Kelp")
+            .oneFish("Cod")
+            .oneFish("Mackerel")
+            .build();
+        assertThat(sea.getGrasses(), contains("Dulse", "Kelp"));
+        assertThat(sea.getFish(), contains("Cod", "Mackerel"));
+    }
+
+}

maven/README.md

@@ -15,3 +15,4 @@
 - [Use the Latest Version of a Dependency in Maven](https://www.baeldung.com/maven-dependency-latest-version)
 - [Multi-Module Project with Maven](https://www.baeldung.com/maven-multi-module)
 - [Maven Enforcer Plugin](https://www.baeldung.com/maven-enforcer-plugin)
+- [Eclipse Error: web.xml is missing and failOnMissingWebXml is set to true](https://www.baeldung.com/eclipse-error-web-xml-missing)

patterns/README.md

@@ -1,3 +1,4 @@
 ### Relevant Articles:
 - [A Guide to the Front Controller Pattern in Java](http://www.baeldung.com/java-front-controller-pattern)
 - [Introduction to Intercepting Filter Pattern in Java](http://www.baeldung.com/intercepting-filter-pattern-in-java)
+- [Introduction to the Null Object Pattern](https://www.baeldung.com/java-null-object-pattern)

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

@@ -7,3 +7,4 @@
 - [Batch Processing in JDBC](http://www.baeldung.com/jdbc-batch-processing)
 - [Introduction to the JDBC RowSet Interface in Java](http://www.baeldung.com/java-jdbc-rowset)
 - [A Simple Guide to Connection Pooling in Java](https://www.baeldung.com/java-connection-pooling)
+- [Guide to the JDBC ResultSet Interface](https://www.baeldung.com/jdbc-resultset)

persistence-modules/hibernate5/pom.xml

@@ -83,13 +83,18 @@
             <artifactId>jmh-generator-annprocess</artifactId>
             <version>${openjdk-jmh.version}</version>
         </dependency>
+        <dependency>
+            <groupId>javax.xml.bind</groupId>
+            <artifactId>jaxb-api</artifactId>
+            <version>2.3.0</version>
+        </dependency>
     </dependencies>
 
     <build>
         <finalName>hibernate5</finalName>
         <resources>
             <resource>
-                <directory>src/main/resources</directory>
+                <directory>src/test/resources</directory>
                 <filtering>true</filtering>
             </resource>
         </resources>

persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/HibernateUtil.java

@@ -113,6 +113,7 @@ public class HibernateUtil {
         metadataSources.addAnnotatedClass(OptimisticLockingCourse.class);
         metadataSources.addAnnotatedClass(OptimisticLockingStudent.class);
         metadataSources.addAnnotatedClass(OfficeEmployee.class);
+        metadataSources.addAnnotatedClass(Post.class);
 
         Metadata metadata = metadataSources.getMetadataBuilder()
                 .applyBasicType(LocalDateStringType.INSTANCE)

persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/pojo/Post.java

@@ -0,0 +1,59 @@
+package com.baeldung.hibernate.pojo;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "posts")
+public class Post {
+
+    @Id
+    @GeneratedValue
+    private int id;
+
+    private String title;
+
+    private String body;
+
+    public Post() { }
+
+    public Post(String title, String body) {
+        this.title = title;
+        this.body = body;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public String getBody() {
+        return body;
+    }
+
+    public void setBody(String body) {
+        this.body = body;
+    }
+
+    @Override
+    public String toString() {
+        return "Post{" +
+                "id=" + id +
+                ", title='" + title + '\'' +
+                ", body='" + body + '\'' +
+                '}';
+    }
+}

persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/transaction/PostService.java

@@ -0,0 +1,29 @@
+package com.baeldung.hibernate.transaction;
+
+import org.hibernate.Session;
+import org.hibernate.Transaction;
+import org.hibernate.query.Query;
+
+public class PostService {
+
+
+    private Session session;
+
+    public PostService(Session session) {
+        this.session = session;
+    }
+
+
+    public void updatePost(String title, String body, int id) {
+        Transaction txn = session.beginTransaction();
+        Query updateQuery = session.createQuery("UPDATE Post p SET p.title = ?1, p.body = ?2 WHERE p.id = ?3");
+        updateQuery.setParameter(1, title);
+        updateQuery.setParameter(2, body);
+        updateQuery.setParameter(3, id);
+        updateQuery.executeUpdate();
+        txn.commit();
+    }
+
+
+
+}

persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/CustomClassIntegrationTest.java

@@ -74,4 +74,6 @@ public class CustomClassIntegrationTest {
         assertEquals("John Smith", result.getEmployeeName());
         assertEquals("Sales", result.getDepartmentName());   
     }
+
+
 }

persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/transaction/TransactionIntegrationTest.java

@@ -0,0 +1,57 @@
+package com.baeldung.hibernate.transaction;
+
+import com.baeldung.hibernate.HibernateUtil;
+import com.baeldung.hibernate.pojo.Post;
+import com.baeldung.hibernate.transaction.PostService;
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.Properties;
+
+import static org.junit.Assert.assertEquals;
+
+public class TransactionIntegrationTest {
+
+    private static PostService postService;
+    private static Session session;
+    private static Logger logger = LoggerFactory.getLogger(TransactionIntegrationTest.class);
+
+    @BeforeClass
+    public static void init() throws IOException {
+        Properties properties = new Properties();
+        properties.setProperty("hibernate.connection.driver_class", "org.h2.Driver");
+        properties.setProperty("hibernate.connection.url", "jdbc:h2:mem:mydb1;DB_CLOSE_DELAY=-1");
+        properties.setProperty("hibernate.connection.username", "sa");
+        properties.setProperty("hibernate.show_sql", "true");
+        properties.setProperty("jdbc.password", "");
+        properties.setProperty("hibernate.dialect", "org.hibernate.dialect.H2Dialect");
+        properties.setProperty("hibernate.hbm2ddl.auto", "create-drop");
+        SessionFactory sessionFactory = HibernateUtil.getSessionFactoryByProperties(properties);
+        session = sessionFactory.openSession();
+        postService = new PostService(session);
+    }
+
+    @Test
+    public void givenTitleAndBody_whenRepositoryUpdatePost_thenUpdatePost() {
+
+        Post post = new Post("This is a title", "This is a sample post");
+        session.persist(post);
+
+        String title = "[UPDATE] Java HowTos";
+        String body = "This is an updated posts on Java how-tos";
+        postService.updatePost(title, body, post.getId());
+
+        session.refresh(post);
+
+        assertEquals(post.getTitle(), title);
+        assertEquals(post.getBody(), body);
+    }
+
+
+}

persistence-modules/java-jpa/README.md

@@ -6,3 +6,4 @@
 - [JPA Entity Graph](https://www.baeldung.com/jpa-entity-graph)
 - [JPA 2.2 Support for Java 8 Date/Time Types](https://www.baeldung.com/jpa-java-time)
 - [Converting Between LocalDate and SQL Date](https://www.baeldung.com/java-convert-localdate-sql-date)
+- [Combining JPA And/Or Criteria Predicates](https://www.baeldung.com/jpa-and-or-criteria-predicates)

persistence-modules/spring-boot-persistence-mongodb/README.md

@@ -1,3 +1,4 @@
 # Relevant Articles
 
 - [Auto-Generated Field for MongoDB using Spring Boot](https://www.baeldung.com/spring-boot-mongodb-auto-generated-field)
+- [Spring Boot Integration Testing with Embedded MongoDB](http://www.baeldung.com/spring-boot-embedded-mongodb)

persistence-modules/spring-boot-persistence-mongodb/pom.xml

@@ -25,6 +25,11 @@
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-data-mongodb</artifactId>
         </dependency>
+        <dependency>
+            <groupId>de.flapdoodle.embed</groupId>
+            <artifactId>de.flapdoodle.embed.mongo</artifactId>
+            <scope>test</scope>
+        </dependency>
         <!-- JUnit Jupiter dependencies -->
         <dependency>
             <groupId>org.junit.jupiter</groupId>
@@ -102,4 +107,4 @@
     </profiles>
 
 
-</project>
+</project>

persistence-modules/spring-boot-persistence-mongodb/src/test/java/com/baeldung/mongodb/MongoDbSpringIntegrationTest.java

@@ -2,7 +2,6 @@ package com.baeldung.mongodb;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
-import org.baeldung.boot.Application;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -12,10 +11,11 @@ import org.springframework.data.mongodb.core.MongoTemplate;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit.jupiter.SpringExtension;
 
+import com.baeldung.SpringBootPersistenceApplication;
 import com.mongodb.BasicDBObjectBuilder;
 import com.mongodb.DBObject;
 
-@ContextConfiguration(classes = Application.class)
+@ContextConfiguration(classes = SpringBootPersistenceApplication.class)
 @DataMongoTest
 @ExtendWith(SpringExtension.class)
 public class MongoDbSpringIntegrationTest {

persistence-modules/spring-boot-persistence/README.MD

@@ -7,3 +7,4 @@
 - [Hibernate Field Naming with Spring Boot](https://www.baeldung.com/hibernate-field-naming-spring-boot)
 - [Integrating Spring Boot with HSQLDB](https://www.baeldung.com/spring-boot-hsqldb)
 - [Configuring a DataSource Programmatically in Spring Boot](https://www.baeldung.com/spring-boot-configure-data-source-programmatic)
+- [Resolving “Failed to Configure a DataSource” Error](https://www.baeldung.com/spring-boot-failed-to-configure-data-source)