Merge branch 'eugenp:master' into master

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

@@ -7,5 +7,6 @@ This module contains articles about Project Jigsaw and the Java Platform Module
 - [Introduction to Project Jigsaw](http://www.baeldung.com/project-jigsaw-java-modularity)
 - [A Guide to Java 9 Modularity](https://www.baeldung.com/java-9-modularity)
 - [Java 9 java.lang.Module API](https://www.baeldung.com/java-9-module-api)
+- [Java 9 Illegal Reflective Access Warning](https://www.baeldung.com/java-illegal-reflective-access)
 
 

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/A01-compile-and-package-baeldung-agent.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+DIR=baeldung-agent
+
+# compile
+mkdir -p out/${DIR}
+javac -d out/${DIR} $(find ${DIR} -type f -name "*.java")
+
+# package
+mkdir -p mods
+jar --create --file=mods/${DIR}.jar --manifest=${DIR}/manifest.txt -C out/${DIR} .

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/A02-compile-and-package-baeldung-reflected.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+DIR=baeldung-reflected
+
+# compile
+mkdir -p out/${DIR}
+javac -d out/${DIR} $(find ${DIR} -type f -name "*.java")
+
+# package
+mkdir -p mods
+jar --create --file=mods/${DIR}.jar -C out/${DIR} .

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/A03-compile-and-package-baeldung-intermedium.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+DIR=baeldung-intermedium
+
+# compile
+mkdir -p out/${DIR}
+javac -d out/${DIR} $(find ${DIR} -type f -name "*.java")
+
+# package
+mkdir -p mods
+jar --create --file=mods/${DIR}.jar -C out/${DIR} .

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/A04-compile-and-package-baeldung-reflecting-named.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+DIR=baeldung-reflecting-named
+
+# compile
+mkdir -p out/${DIR}
+javac -d out/${DIR} --module-path mods $(find ${DIR} -type f -name "*.java")
+
+# package
+mkdir -p mods
+jar --create --file=mods/${DIR}.jar -C out/${DIR} .

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/A05-compile-and-package-baeldung-reflecting-unnamed.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+DIR=baeldung-reflecting-unnamed
+
+# compile
+mkdir -p out/${DIR}
+javac -d out/${DIR} $(find ${DIR} -type f -name "*.java")
+
+# package
+mkdir -p mods
+jar --create --file=mods/${DIR}.jar -C out/${DIR} .

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/B01-runtime-baeldung-reflecting-named-using-add-opens.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+java --module-path mods \
+     --add-opens baeldung.reflected/com.baeldung.reflected.internal=baeldung.reflecting.named \
+     --module baeldung.reflecting.named/com.baeldung.reflecting.named.Main

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/B02-runtime-baeldung-reflecting-named-using-forward-opens.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+java --module-path mods \
+     --add-opens baeldung.reflected/com.baeldung.reflected.internal=baeldung.intermedium \
+     --module baeldung.reflecting.named/com.baeldung.reflecting.named.MainWithForwardOpen

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/B03-runtime-baeldung-reflecting-named-using-java-agent.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+java --module-path mods \
+     -javaagent:mods/baeldung-agent.jar=com.baeldung.reflected.internal.InternalNonPublicClass,com.baeldung.reflecting.named.Main \
+     --module baeldung.reflecting.named/com.baeldung.reflecting.named.Main

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/B04-runtime-baeldung-reflecting-unnamed-with-warning.sh

@@ -0,0 +1,2 @@
+#!/bin/bash
+java -cp "mods/*" com.baeldung.reflecting.unnamed.Main

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/B05-runtime-baeldung-reflecting-unnamed-using-add-opens.sh

@@ -0,0 +1,2 @@
+#!/bin/bash
+java -cp "mods/*" --add-opens java.base/java.lang=ALL-UNNAMED com.baeldung.reflecting.unnamed.Main

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/B06-runtime-baeldung-reflecting-unnamed-using-java-agent.sh

@@ -0,0 +1,2 @@
+#!/bin/bash
+java -cp "mods/*" -javaagent:mods/baeldung-agent.jar com.baeldung.reflecting.unnamed.Main

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/C01-clean.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+
+rm -rf out
+rm -rf mods

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-agent/com/baeldung/agent/LoadTimeAgent.java

@@ -0,0 +1,69 @@
+package com.baeldung.agent;
+
+import java.lang.instrument.Instrumentation;
+import java.util.*;
+
+public class LoadTimeAgent {
+    public static void premain(String agentArgs, Instrumentation inst) {
+        System.out.println("agentArgs: " + agentArgs);
+
+        if (agentArgs != null) {
+            addExportsAndOpensByClassName(inst, agentArgs);
+        }
+        else {
+            addExportsAndOpensToUnnamedModule(inst);
+        }
+    }
+
+    private static void addExportsAndOpensByClassName(Instrumentation inst, String agentArgs) {
+        String[] array = agentArgs.split(",");
+        try {
+            String className1 = array[0];
+            String className2 = array[1];
+            Class<?> clazz1 = Class.forName(className1);
+            Class<?> clazz2 = Class.forName(className2);
+
+            Module srcModule = clazz1.getModule();
+            Module targetModule = clazz2.getModule();
+            redefineModule(inst, srcModule, targetModule);
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+        }
+    }
+
+    private static void addExportsAndOpensToUnnamedModule(Instrumentation inst) {
+        Module unnamedModule = ClassLoader.getSystemClassLoader().getUnnamedModule();
+        Set<Module> modules = ModuleLayer.boot().modules();
+
+        for (Module m : modules) {
+            redefineModule(inst, m, unnamedModule);
+        }
+    }
+
+    private static void redefineModule(Instrumentation inst, Module src, Module target) {
+        // prepare extra reads
+        Set<Module> extraReads = Collections.singleton(target);
+
+        // prepare extra exports
+        Set<String> packages = src.getPackages();
+        Map<String, Set<Module>> extraExports = new HashMap<>();
+        for (String pkg : packages) {
+            extraExports.put(pkg, extraReads);
+        }
+
+        // prepare extra opens
+        Map<String, Set<Module>> extraOpens = new HashMap<>();
+        for (String pkg : packages) {
+            extraOpens.put(pkg, extraReads);
+        }
+
+        // prepare extra uses
+        Set<Class<?>> extraUses = Collections.emptySet();
+
+        // prepare extra provides
+        Map<Class<?>, List<Class<?>>> extraProvides = Collections.emptyMap();
+
+        // redefine module
+        inst.redefineModule(src, extraReads, extraExports, extraOpens, extraUses, extraProvides);
+    }
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-agent/manifest.txt

@@ -0,0 +1,3 @@
+Premain-Class: com.baeldung.agent.LoadTimeAgent
+Can-Redefine-Classes: true
+Can-Retransform-Classes: true

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-agent/module-info.java

@@ -0,0 +1,3 @@
+module baeldung.agent {
+    requires java.instrument;
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-intermedium/com/baeldung/intermedium/ForwardOpen.java

@@ -0,0 +1,15 @@
+package com.baeldung.intermedium;
+
+public class ForwardOpen {
+    public static void addOpens(Class<?> clazz1, Class<?> clazz2) {
+        Module currentModule = ForwardOpen.class.getModule();
+        Module srcModule = clazz1.getModule();
+        Module targetModule = clazz2.getModule();
+
+        System.out.println("current module: " + currentModule.getName());
+        System.out.println("source  module: " + srcModule.getName());
+        System.out.println("target  module: " + targetModule.getName());
+
+        srcModule.addOpens(clazz1.getPackageName(), targetModule);
+    }
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-intermedium/module-info.java

@@ -0,0 +1,3 @@
+module baeldung.intermedium {
+    exports com.baeldung.intermedium;
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflected/com/baeldung/reflected/exported/ExportedNonPublicClass.java

@@ -0,0 +1,11 @@
+package com.baeldung.reflected.exported;
+
+class ExportedNonPublicClass {
+    public static void testPublicStaticMethod() {
+        System.out.println("ExportedNonPublicClass.testPublicStaticMethod()");
+    }
+
+    private static void testPrivateStaticMethod() {
+        System.out.println("ExportedNonPublicClass.testPrivateStaticMethod()");
+    }
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflected/com/baeldung/reflected/exported/ExportedPublicClass.java

@@ -0,0 +1,11 @@
+package com.baeldung.reflected.exported;
+
+public class ExportedPublicClass {
+    public static void testPublicStaticMethod() {
+        System.out.println("ExportedPublicClass.testPublicStaticMethod()");
+    }
+
+    private static void testPrivateStaticMethod() {
+        System.out.println("ExportedPublicClass.testPrivateStaticMethod()");
+    }
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflected/com/baeldung/reflected/internal/InternalNonPublicClass.java

@@ -0,0 +1,11 @@
+package com.baeldung.reflected.internal;
+
+class InternalNonPublicClass {
+    public static void testPublicStaticMethod() {
+        System.out.println("InternalNonPublicClass.testPublicStaticMethod()");
+    }
+
+    private static void testPrivateStaticMethod() {
+        System.out.println("InternalNonPublicClass.testPrivateStaticMethod()");
+    }
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflected/com/baeldung/reflected/internal/InternalPublicClass.java

@@ -0,0 +1,11 @@
+package com.baeldung.reflected.internal;
+
+public class InternalPublicClass {
+    public static void testPublicStaticMethod() {
+        System.out.println("InternalPublicClass.testPublicStaticMethod()");
+    }
+
+    private static void testPrivateStaticMethod() {
+        System.out.println("InternalPublicClass.testPrivateStaticMethod()");
+    }
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflected/com/baeldung/reflected/opened/OpenedNonPublicClass.java

@@ -0,0 +1,11 @@
+package com.baeldung.reflected.opened;
+
+class OpenedNonPublicClass {
+    public static void testPublicStaticMethod() {
+        System.out.println("OpenedNonPublicClass.testPublicStaticMethod()");
+    }
+
+    private static void testPrivateStaticMethod() {
+        System.out.println("OpenedNonPublicClass.testPrivateStaticMethod()");
+    }
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflected/com/baeldung/reflected/opened/OpenedPublicClass.java

@@ -0,0 +1,11 @@
+package com.baeldung.reflected.opened;
+
+public class OpenedPublicClass {
+    public static void testPublicStaticMethod() {
+        System.out.println("OpenedPublicClass.testPublicStaticMethod()");
+    }
+
+    private static void testPrivateStaticMethod() {
+        System.out.println("OpenedPublicClass.testPrivateStaticMethod()");
+    }
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflected/module-info.java

@@ -0,0 +1,4 @@
+module baeldung.reflected {
+    exports com.baeldung.reflected.exported;
+    opens com.baeldung.reflected.opened;
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflecting-named/com/baeldung/reflecting/named/Main.java

@@ -0,0 +1,12 @@
+package com.baeldung.reflecting.named;
+
+import java.lang.reflect.Method;
+
+public class Main {
+    public static void main(String[] args) throws Exception {
+        Class<?> clazz = Class.forName("com.baeldung.reflected.internal.InternalNonPublicClass");
+        Method method = clazz.getDeclaredMethod("testPrivateStaticMethod");
+        method.setAccessible(true);
+        method.invoke(null);
+    }
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflecting-named/com/baeldung/reflecting/named/MainWithForwardOpen.java

@@ -0,0 +1,18 @@
+package com.baeldung.reflecting.named;
+
+import com.baeldung.intermedium.ForwardOpen;
+
+import java.lang.reflect.Method;
+
+public class MainWithForwardOpen {
+    public static void main(String[] args) throws Exception {
+        Class<?> currentClass = Main.class;
+        Class<?> clazz = Class.forName("com.baeldung.reflected.internal.InternalNonPublicClass");
+
+        ForwardOpen.addOpens(clazz, currentClass);
+
+        Method method = clazz.getDeclaredMethod("testPrivateStaticMethod");
+        method.setAccessible(true);
+        method.invoke(null);
+    }
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflecting-named/module-info.java

@@ -0,0 +1,4 @@
+module baeldung.reflecting.named {
+    requires baeldung.intermedium;
+    requires baeldung.reflected;
+}

core-java-modules/core-java-9-jigsaw/src/modules/com.baeldung.reflective.access/baeldung-reflecting-unnamed/com/baeldung/reflecting/unnamed/Main.java

@@ -0,0 +1,13 @@
+package com.baeldung.reflecting.unnamed;
+
+import java.lang.reflect.Field;
+
+public class Main {
+    public static void main(String[] args) throws Exception {
+        Class<?> clazz = StringBuilder.class;
+        Field f = clazz.getDeclaredField("serialVersionUID");
+        f.setAccessible(true);
+        Object value = f.get(null);
+        System.out.println(value);
+    }
+}

core-java-modules/core-java-collections-list-3/src/main/java/com/baeldung/list/listvsarraylist/ArrayListDemo.java

@@ -0,0 +1,51 @@
+package com.baeldung.list.listvsarraylist;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Locale;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class ArrayListDemo {
+
+    private ArrayList<Passenger> passengers = new ArrayList<>(20);
+//    private LinkedList<Passenger> passengers = new LinkedList<>(); // compile time error
+
+    public ArrayList<Passenger> addPassenger(Passenger passenger) {
+        passengers.add(passenger);
+        return passengers;
+    }
+    
+    public ArrayList<Passenger> removePassenger(Passenger passenger) {
+        passengers.remove(passenger);
+        return passengers;
+    }
+
+    public ArrayList<Passenger> getPassengersBySource(String source) {
+        return new ArrayList<Passenger>(passengers.stream()
+            .filter(it -> it.getSource().equals(source))
+            .collect(Collectors.toList()));
+    }
+    
+    public ArrayList<Passenger> getPassengersByDestination(String destination) {
+        return new ArrayList<Passenger> (passengers.stream()
+            .filter(it -> it.getDestination().equals(destination))
+            .collect(Collectors.toList()));
+    }
+    
+    public long getKidsCount(ArrayList<Passenger> passengerList) {
+        return passengerList.stream()
+            .filter(it -> (it.getAge() <= 10))
+            .count();
+    }
+
+    public ArrayList<Passenger> getFinalPassengersList() {
+        return new ArrayList<Passenger> (Collections.unmodifiableList(passengers));
+    }
+
+    public ArrayList<String> getServicedCountries() {
+        return new ArrayList<String> (Stream.of(Locale.getISOCountries())
+            .collect(Collectors.toList()));
+    }
+
+}

core-java-modules/core-java-collections-list-3/src/main/java/com/baeldung/list/listvsarraylist/ListDemo.java

@@ -0,0 +1,53 @@
+package com.baeldung.list.listvsarraylist;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Locale;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class ListDemo {
+
+    private List<Passenger> passengers = new ArrayList<>(20);
+//    private List<Passenger> passengers = new LinkedList<>(); // No compile time error
+
+    public List<Passenger> addPassenger(Passenger passenger) {
+        passengers.add(passenger);
+        return passengers;
+    }
+    
+    public List<Passenger> removePassenger(Passenger passenger) {
+        passengers.remove(passenger);
+        return passengers;
+    }
+
+    public List<Passenger> getPassengersBySource(String source) {
+        return passengers.stream()
+            .filter(it -> it.getSource().equals(source))
+            .collect(Collectors.toList());
+    }
+    
+    public List<Passenger> getPassengersByDestination(String destination) {
+        return passengers.stream()
+            .filter(it -> it.getDestination().equals(destination))
+            .collect(Collectors.toList());
+    }
+    
+    public long getKidsCount(List<Passenger> passengerList) {
+        return passengerList.stream()
+            .filter(it -> (it.getAge() <= 10))
+            .count();
+    }
+
+    public List<Passenger> getFinalPassengersList() {
+        return Collections.unmodifiableList(passengers);
+    }
+
+    public List<String> getServicedCountries() {
+        return Stream.of(Locale.getISOCountries())
+            .collect(Collectors.toList());
+    }
+
+}

core-java-modules/core-java-collections-list-3/src/main/java/com/baeldung/list/listvsarraylist/Passenger.java

@@ -0,0 +1,49 @@
+package com.baeldung.list.listvsarraylist;
+
+public class Passenger {
+
+    private String name;
+    private int age;
+    private String source;
+    private String destination;
+
+    public Passenger(String name, int age, String source, String destination) {
+        this.name = name;
+        this.age = age;
+        this.source = source;
+        this.destination = destination;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public String getSource() {
+        return source;
+    }
+
+    public void setSource(String source) {
+        this.source = source;
+    }
+
+    public String getDestination() {
+        return destination;
+    }
+
+    public void setDestination(String destination) {
+        this.destination = destination;
+    }
+
+}

core-java-modules/core-java-collections-list-3/src/test/java/com/baeldung/list/listvsarraylist/ArrayListDemoUnitTest.java

@@ -0,0 +1,91 @@
+package com.baeldung.list.listvsarraylist;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertNotNull;
+
+import java.util.ArrayList;
+import java.util.Locale;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class ArrayListDemoUnitTest {
+
+    ArrayListDemo application = new ArrayListDemo();
+
+    Passenger passenger1;
+    Passenger passenger2;
+    Passenger passenger3;
+
+    @BeforeEach
+    protected void setUp() {
+        passenger1 = new Passenger("Anna", 25, "London", "New York");
+        passenger2 = new Passenger("Binny", 35, "New York", "London");
+        passenger3 = new Passenger("Chandra", 8, "Paris", "New Delhi");
+        application.addPassenger(passenger1);
+        application.addPassenger(passenger2);
+        application.addPassenger(passenger3);
+    }
+
+    @Test
+    public void givenEmptyList_whenAddedPassenger_thenReturnCurrentPassengerList() {
+        ArrayList<Passenger> list = application.addPassenger(new Passenger("David", 54, "Milan", "Paris"));
+
+        assertNotNull(list);
+        assertThat(list).hasSize(4);
+    }
+
+    @Test
+    public void givenPassengerList_whenRemovedPassenger_thenReturnCurrentPassengerList() {
+        ArrayList<Passenger> list = application.removePassenger(passenger3);
+
+        assertNotNull(list);
+        assertThat(list).hasSize(2);
+    }
+
+    @Test
+    public void givenPassengerList_whenPassedWithSourceCity_thenReturnMatchingPassengerList() {
+        ArrayList<Passenger> list = application.getPassengersBySource("Singapore");
+        ArrayList<Passenger> list2 = application.getPassengersBySource("London");
+
+        assertThat(list).isEmpty();
+        assertThat(list2.get(0)).isEqualTo(passenger1);
+    }
+
+    @Test
+    public void givenPassengerList_whenPassedWithDestinationCity_thenReturnMatchingPassengerList() {
+        ArrayList<Passenger> list = application.getPassengersByDestination("Singapore");
+        ArrayList<Passenger> list2 = application.getPassengersByDestination("London");
+
+        assertThat(list).isEmpty();
+        assertThat(list2.get(0)).isEqualTo(passenger2);
+    }
+
+    @Test
+    public void givenPassengerList_whenFindKidsByAge_thenReturnKidsList() {
+        ArrayList<Passenger> list = new ArrayList<>();
+        list.add(passenger1);
+        list.add(passenger2);
+        list.add(passenger3);
+        long count = application.getKidsCount(list);
+
+        assertThat(count).isEqualTo(1);
+    }
+
+    @Test
+    public void givenPassengerList_whenCalledWithCollectionsFunction_thenReturnsListType() {
+        ArrayList<Passenger> list = application.getFinalPassengersList();
+
+        assertNotNull(list);
+        assertThat(list).hasSize(3);
+    }
+
+    @Test
+    public void givenCurrentLocale_whenUsingStreams_thenReturnsListType() {
+        ArrayList<String> servicedCountries = application.getServicedCountries();
+
+        assertNotNull(servicedCountries);
+        assertThat(servicedCountries).hasSize(Locale.getISOCountries().length);
+    }
+
+}

core-java-modules/core-java-collections-list-3/src/test/java/com/baeldung/list/listvsarraylist/ListDemoUnitTest.java

@@ -0,0 +1,92 @@
+package com.baeldung.list.listvsarraylist;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertNotNull;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class ListDemoUnitTest {
+
+    ListDemo application = new ListDemo();
+
+    Passenger passenger1;
+    Passenger passenger2;
+    Passenger passenger3;
+
+    @BeforeEach
+    protected void setUp() {
+        passenger1 = new Passenger("Anna", 25, "London", "New York");
+        passenger2 = new Passenger("Binny", 35, "New York", "London");
+        passenger3 = new Passenger("Chandra", 8, "Paris", "New Delhi");
+        application.addPassenger(passenger1);
+        application.addPassenger(passenger2);
+        application.addPassenger(passenger3);
+    }
+
+    @Test
+    public void givenEmptyList_whenAddedPassenger_thenReturnCurrentPassengerList() {
+        List<Passenger> list = application.addPassenger(new Passenger("David", 54, "Milan", "Paris"));
+
+        assertNotNull(list);
+        assertThat(list).hasSize(4);
+    }
+
+    @Test
+    public void givenPresentList_whenRemovedPassenger_thenReturnCurrentPassengerList() {
+        List<Passenger> list = application.removePassenger(passenger3);
+
+        assertNotNull(list);
+        assertThat(list).hasSize(2);
+    }
+
+    @Test
+    public void givenPresentList_whenPassedWithSourceCity_thenReturnMatchingPassengerList() {
+        List<Passenger> list = application.getPassengersBySource("Singapore");
+        List<Passenger> list2 = application.getPassengersBySource("London");
+
+        assertThat(list).isEmpty();
+        assertThat(list2.get(0)).isEqualTo(passenger1);
+    }
+
+    @Test
+    public void givenPresentList_whenPassedWithDestinationCity_thenReturnMatchingPassengerList() {
+        List<Passenger> list = application.getPassengersByDestination("Singapore");
+        List<Passenger> list2 = application.getPassengersByDestination("London");
+
+        assertThat(list).isEmpty();
+        assertThat(list2.get(0)).isEqualTo(passenger2);
+    }
+
+    @Test
+    public void givenPassengerList_whenFindKidsByAge_thenReturnKidsList() {
+        List<Passenger> list = new ArrayList<>();
+        list.add(passenger1);
+        list.add(passenger2);
+        list.add(passenger3);
+        long count = application.getKidsCount(list);
+
+        assertThat(count).isEqualTo(1);
+    }
+
+    @Test
+    public void givenPresentList_whenCalledWithCollectionsFunction_thenReturnsListType() {
+        List<Passenger> list = application.getFinalPassengersList();
+
+        assertNotNull(list);
+        assertThat(list).hasSize(3);
+    }
+
+    @Test
+    public void givenCurrentLocale_whenUsingStreams_thenReturnsListType() {
+        List<String> servicedCountries = application.getServicedCountries();
+
+        assertNotNull(servicedCountries);
+        assertThat(servicedCountries).hasSize(Locale.getISOCountries().length);
+    }
+
+}

core-java-modules/core-java-collections-list/src/test/java/com/baeldung/list/listOfHashMaps/ListOfHashMapsUnitTest.java

@@ -0,0 +1,36 @@
+package test.java.com.baeldung.list.listOfHashMaps;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static org.junit.Assert.assertTrue;
+
+public class ListOfHashMapsUnitTest {
+    List<HashMap<String, List<String>>> booksAuthorsMapsList = new ArrayList<>();
+
+    @Test
+    public void givenMaps_whenAddToList_thenListContainsMaps() {
+        HashMap<String, List<String>> javaBooksAuthorsMap = new HashMap<>();
+        HashMap<String, List<String>> phpBooksAuthorsMap = new HashMap<>();
+        javaBooksAuthorsMap.put("Head First Java", Arrays.asList("Kathy Sierra", "Bert Bates"));
+        javaBooksAuthorsMap.put("Effective Java", Arrays.asList("Joshua Bloch"));
+        javaBooksAuthorsMap.put("OCA Java SE 8",
+                Arrays.asList("Kathy Sierra", "Bert Bates", "Elisabeth Robson"));
+        phpBooksAuthorsMap.put("The Joy of PHP", Arrays.asList("Alan Forbes"));
+        phpBooksAuthorsMap.put("Head First PHP &amp; MySQL",
+                Arrays.asList("Lynn Beighley", "Michael Morrison"));
+
+        booksAuthorsMapsList.add(javaBooksAuthorsMap);
+        booksAuthorsMapsList.add(phpBooksAuthorsMap);
+
+        assertTrue(booksAuthorsMapsList.get(0).keySet().containsAll
+                (javaBooksAuthorsMap.keySet().stream().collect(Collectors.toList())));
+        assertTrue(booksAuthorsMapsList.get(1).keySet().containsAll
+                (phpBooksAuthorsMap.keySet().stream().collect(Collectors.toList())));
+    }
+}

core-java-modules/core-java-regex-2/regexMatchToArray/src/regex/array/RegexMatches.java

@@ -0,0 +1,24 @@
+package regex.array;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.*;
+	
+class RegexMatches {
+	
+    String[] regexMatch(String strSearch)
+	{
+	    List<String> matchesList = new ArrayList<String>();
+	    String stringToSearch = strSearch;
+	    Pattern p1 = Pattern.compile("780{1}\\d{7}");
+	    Matcher m1 = p1.matcher(stringToSearch);
+	    while (m1.find()) 
+	    {
+	    	matchesList.add(m1.group());
+	    }
+	    int sizeOfNewArray = matchesList.size();
+	    String newArrayOfMatches[] = new String[sizeOfNewArray];
+	    matchesList.toArray(newArrayOfMatches);
+	    return newArrayOfMatches;
+	}
+}

core-java-modules/core-java-regex-2/regexMatchToArray/test/regex/array/RegexMatchesUnitTest.java

@@ -0,0 +1,33 @@
+package regex.array;
+
+import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.Test;
+
+import regex.array.RegexMatches;
+
+class RegexMatchesUnitTest {
+
+	@Test
+	void whenFourNums_thenFourMatches() {
+		RegexMatches rm = new RegexMatches();
+		String actual[] = rm.regexMatch("7801111211fsdafasdfa  7802222222  sadfsadfsda7803333333 sadfdasfasd 7804444444");
+		
+		assertArrayEquals(new String[] {"7801111211", "7802222222", "7803333333", "7804444444"}, actual, "success");
+	}
+
+	@Test
+	void whenThreeNums_thenThreeMatches() {
+		RegexMatches rm = new RegexMatches();
+		String actual[] = rm.regexMatch("7801111211fsdafasdfa  780222222  sadfsadfsda7803333333 sadfdasfasd 7804444444");
+		
+		assertArrayEquals(new String[] {"7801111211", "7803333333", "7804444444"}, actual, "success");
+	}
+
+	@Test
+	void whenZeroNums_thenZeroMatches() {
+		RegexMatches rm = new RegexMatches();
+		String actual[] = rm.regexMatch("78011111fsdafasdfa  780222222  sadfsadfsda78033333 sadfdasfasd 7804444");
+		
+		assertArrayEquals(new String[] {}, actual, "success");
+	}
+}

graphql/graphql-error-handling/pom.xml

@@ -0,0 +1,97 @@
+<?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.graphql</groupId>
+    <artifactId>graphql-error-handling</artifactId>
+    <version>1.0</version>
+    <packaging>jar</packaging>
+    <name>graphql-error-handling</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-2</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-2</relativePath>
+    </parent>
+
+    <properties>
+        <java.version>1.8</java.version>
+        <lombok.version>1.18.18</lombok.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-jpa</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-spring-boot-starter</artifactId>
+            <version>5.0.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java-tools</artifactId>
+            <version>5.2.4</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <version>${h2.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-test</artifactId>
+            <scope>test</scope>
+            <version>2.6.4</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+            <version>5.0.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.22.0</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.skyscreamer</groupId>
+            <artifactId>jsonassert</artifactId>
+            <version>1.5.0</version>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+</project>

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/GraphQLErrorHandlerApplication.java

@@ -0,0 +1,46 @@
+package com.baeldung.graphql.error.handling;
+
+import com.baeldung.graphql.error.handling.exception.GraphQLErrorAdapter;
+import graphql.ExceptionWhileDataFetching;
+import graphql.GraphQLError;
+import graphql.servlet.GraphQLErrorHandler;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+@SpringBootApplication
+public class GraphQLErrorHandlerApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(GraphQLErrorHandlerApplication.class, args);
+    }
+
+    @Bean
+	public GraphQLErrorHandler errorHandler() {
+		return new GraphQLErrorHandler() {
+			@Override
+			public List<GraphQLError> processErrors(List<GraphQLError> errors) {
+				List<GraphQLError> clientErrors = errors.stream()
+						.filter(this::isClientError)
+						.collect(Collectors.toList());
+
+				List<GraphQLError> serverErrors = errors.stream()
+						.filter(e -> !isClientError(e))
+						.map(GraphQLErrorAdapter::new)
+						.collect(Collectors.toList());
+
+				List<GraphQLError> e = new ArrayList<>();
+				e.addAll(clientErrors);
+				e.addAll(serverErrors);
+				return e;
+			}
+
+			private boolean isClientError(GraphQLError error) {
+				return !(error instanceof ExceptionWhileDataFetching || error instanceof Throwable);
+			}
+		};
+	}
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/domain/Location.java

@@ -0,0 +1,29 @@
+package com.baeldung.graphql.error.handling.domain;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.Entity;
+import javax.persistence.FetchType;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+import java.util.ArrayList;
+import java.util.List;
+
+@Data
+@Entity
+@Builder
+@AllArgsConstructor
+@NoArgsConstructor
+public class Location {
+    @Id
+    private String zipcode;
+
+    private String city;
+    private String state;
+
+    @OneToMany(mappedBy = "location", fetch = FetchType.EAGER)
+    private List<Vehicle> vehicles = new ArrayList<>();
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/domain/Vehicle.java

@@ -0,0 +1,26 @@
+package com.baeldung.graphql.error.handling.domain;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.*;
+
+@Data
+@Entity
+@Builder
+@AllArgsConstructor
+@NoArgsConstructor
+public class Vehicle {
+    @Id
+    private String vin;
+    private Integer year;
+    private String make;
+    private String model;
+    private String trim;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "fk_location")
+    private Location location;
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/exception/AbstractGraphQLException.java

@@ -0,0 +1,44 @@
+package com.baeldung.graphql.error.handling.exception;
+
+import graphql.ErrorType;
+import graphql.GraphQLError;
+import graphql.language.SourceLocation;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class AbstractGraphQLException extends RuntimeException implements GraphQLError {
+    private Map<String, Object> parameters = new HashMap();
+
+    public AbstractGraphQLException(String message) {
+        super(message);
+    }
+
+    public AbstractGraphQLException(String message, Map<String, Object> additionParams) {
+        this(message);
+        if (additionParams != null) {
+            parameters = additionParams;
+        }
+    }
+
+    @Override
+    public String getMessage() {
+        return super.getMessage();
+    }
+
+    @Override
+    public List<SourceLocation> getLocations() {
+        return null;
+    }
+
+    @Override
+    public ErrorType getErrorType() {
+        return null;
+    }
+
+    @Override
+    public Map<String, Object> getExtensions() {
+        return this.parameters;
+    }
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/exception/GraphQLErrorAdapter.java

@@ -0,0 +1,48 @@
+package com.baeldung.graphql.error.handling.exception;
+
+import graphql.ErrorType;
+import graphql.ExceptionWhileDataFetching;
+import graphql.GraphQLError;
+import graphql.language.SourceLocation;
+
+import java.util.List;
+import java.util.Map;
+
+public class GraphQLErrorAdapter implements GraphQLError {
+
+    private GraphQLError error;
+
+    public GraphQLErrorAdapter(GraphQLError error) {
+        this.error = error;
+    }
+
+    @Override
+    public Map<String, Object> getExtensions() {
+        return error.getExtensions();
+    }
+
+    @Override
+    public List<SourceLocation> getLocations() {
+        return error.getLocations();
+    }
+
+    @Override
+    public ErrorType getErrorType() {
+        return error.getErrorType();
+    }
+
+    @Override
+    public List<Object> getPath() {
+        return error.getPath();
+    }
+
+    @Override
+    public Map<String, Object> toSpecification() {
+        return error.toSpecification();
+    }
+
+    @Override
+    public String getMessage() {
+        return (error instanceof ExceptionWhileDataFetching) ? ((ExceptionWhileDataFetching) error).getException().getMessage() : error.getMessage();
+    }
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/exception/InvalidInputException.java

@@ -0,0 +1,7 @@
+package com.baeldung.graphql.error.handling.exception;
+
+public class InvalidInputException extends RuntimeException {
+    public InvalidInputException(String message) {
+        super(message);
+    }
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/exception/VehicleAlreadyPresentException.java

@@ -0,0 +1,14 @@
+package com.baeldung.graphql.error.handling.exception;
+
+import java.util.Map;
+
+public class VehicleAlreadyPresentException extends AbstractGraphQLException {
+
+     public VehicleAlreadyPresentException(String message) {
+         super(message);
+     }
+
+    public VehicleAlreadyPresentException(String message, Map<String, Object> additionParams) {
+        super(message, additionParams);
+    }
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/exception/VehicleNotFoundException.java

@@ -0,0 +1,14 @@
+package com.baeldung.graphql.error.handling.exception;
+
+import java.util.Map;
+
+public class VehicleNotFoundException extends AbstractGraphQLException {
+
+    public VehicleNotFoundException(String message) {
+        super(message);
+    }
+
+    public VehicleNotFoundException(String message, Map<String, Object> params) {
+        super(message, params);
+    }
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/repository/InventoryRepository.java

@@ -0,0 +1,9 @@
+package com.baeldung.graphql.error.handling.repository;
+
+import com.baeldung.graphql.error.handling.domain.Vehicle;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface InventoryRepository extends JpaRepository<Vehicle, String>  {
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/repository/LocationRepository.java

@@ -0,0 +1,9 @@
+package com.baeldung.graphql.error.handling.repository;
+
+import com.baeldung.graphql.error.handling.domain.Location;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface LocationRepository extends JpaRepository<Location, String>  {
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/resolver/Mutation.java

@@ -0,0 +1,20 @@
+package com.baeldung.graphql.error.handling.resolver;
+
+import com.baeldung.graphql.error.handling.domain.Location;
+import com.baeldung.graphql.error.handling.domain.Vehicle;
+import com.baeldung.graphql.error.handling.service.InventoryService;
+import com.coxautodev.graphql.tools.GraphQLMutationResolver;
+import org.springframework.stereotype.Component;
+
+@Component
+public class Mutation implements GraphQLMutationResolver {
+    private InventoryService inventoryService;
+
+    public Mutation(InventoryService inventoryService) {
+        this.inventoryService = inventoryService;
+    }
+
+    public Vehicle addVehicle(String vin, Integer year, String make, String model, String trim, Location location) {
+        return this.inventoryService.addVehicle(vin, year, make, model, trim, location);
+    }
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/resolver/Query.java

@@ -0,0 +1,29 @@
+package com.baeldung.graphql.error.handling.resolver;
+
+import com.baeldung.graphql.error.handling.domain.Vehicle;
+import com.baeldung.graphql.error.handling.service.InventoryService;
+import com.coxautodev.graphql.tools.GraphQLQueryResolver;
+import org.springframework.stereotype.Component;
+
+import java.util.List;
+
+@Component
+public class Query implements GraphQLQueryResolver  {
+    private final InventoryService inventoryService;
+
+    public Query(InventoryService inventoryService) {
+        this.inventoryService = inventoryService;
+    }
+
+    public List<Vehicle> searchAll() {
+        return this.inventoryService.searchAll();
+    }
+
+    public List<Vehicle> searchByLocation(String zipcode) {
+        return this.inventoryService.searchByLocation(zipcode);
+    }
+
+    public Vehicle searchByVin(String vin) {
+        return this.inventoryService.searchByVin(vin);
+    }
+}

graphql/graphql-error-handling/src/main/java/com/baeldung/graphql/error/handling/service/InventoryService.java

@@ -0,0 +1,67 @@
+package com.baeldung.graphql.error.handling.service;
+
+import com.baeldung.graphql.error.handling.domain.Location;
+import com.baeldung.graphql.error.handling.domain.Vehicle;
+import com.baeldung.graphql.error.handling.exception.InvalidInputException;
+import com.baeldung.graphql.error.handling.exception.VehicleAlreadyPresentException;
+import com.baeldung.graphql.error.handling.exception.VehicleNotFoundException;
+import com.baeldung.graphql.error.handling.repository.InventoryRepository;
+import com.baeldung.graphql.error.handling.repository.LocationRepository;
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.stereotype.Service;
+
+import javax.transaction.Transactional;
+import java.util.*;
+
+@Service
+public class InventoryService {
+    private InventoryRepository inventoryRepository;
+    private LocationRepository locationRepository;
+
+    public InventoryService(InventoryRepository inventoryRepository, LocationRepository locationRepository) {
+        this.inventoryRepository = inventoryRepository;
+        this.locationRepository = locationRepository;
+    }
+
+    @Transactional
+    public Vehicle addVehicle(String vin, Integer year, String make, String model, String trim, Location location) {
+        Optional<Vehicle> existingVehicle = this.inventoryRepository.findById(vin);
+        if (existingVehicle.isPresent()) {
+            Map<String, Object> params = new HashMap<>();
+            params.put("vin", vin);
+            throw new VehicleAlreadyPresentException("Failed to add vehicle. Vehicle with vin " + vin + " already present.", params);
+        }
+        Vehicle vehicle = Vehicle.builder()
+                .vin(vin)
+                .year(year)
+                .make(make)
+                .model(model)
+                .location(location)
+                .trim(trim)
+                .build();
+
+        this.locationRepository.save(location);
+        return this.inventoryRepository.save(vehicle);
+    }
+
+    public List<Vehicle> searchAll() {
+        return this.inventoryRepository.findAll();
+    }
+
+    public List<Vehicle> searchByLocation(String zipcode) {
+        if (StringUtils.isEmpty(zipcode) || zipcode.length() != 5) {
+            throw new InvalidInputException("Invalid zipcode " + zipcode + " provided.");
+        }
+        return this.locationRepository.findById(zipcode)
+                .map(Location::getVehicles)
+                .orElse(new ArrayList<>());
+    }
+
+    public Vehicle searchByVin(String vin) {
+        return this.inventoryRepository.findById(vin).orElseThrow(() -> {
+            Map<String, Object> params = new HashMap<>();
+            params.put("vin", vin);
+            return new VehicleNotFoundException("Vehicle with vin " + vin + " not found.", params);
+        });
+    }
+}

graphql/graphql-error-handling/src/main/resources/application.yml

@@ -0,0 +1,23 @@
+graphql:
+  servlet:
+    mapping: /graphql
+
+spring:
+  datasource:
+    url: "jdbc:h2:mem:graphqldb"
+    driverClassName: "org.h2.Driver"
+    username: sa
+    password:
+
+    initialization-mode: always
+    platform: h2
+
+  jpa:
+    show-sql: true
+    properties:
+      hibernate:
+        dialect: org.hibernate.dialect.H2Dialect
+        ddl-auto: none
+
+  h2:
+    console.enabled: true

graphql/graphql-error-handling/src/main/resources/graphql/inventory.graphqls

@@ -0,0 +1,23 @@
+type Vehicle {
+  vin: ID!
+  year: Int!
+  make: String!
+  model: String!
+  trim: String!
+}
+
+input Location {
+  city: String
+  state: String
+  zipcode: String!
+}
+
+type Query {
+  searchAll:  [Vehicle]!
+  searchByLocation(zipcode: String!): [Vehicle]!
+  searchByVin(vin: String!): Vehicle
+}
+
+type Mutation {
+  addVehicle(vin: ID!, year: Int!, make: String!, model: String!, trim: String, location: Location): Vehicle!
+}

graphql/graphql-error-handling/src/main/resources/import.sql

@@ -0,0 +1,7 @@
+insert into LOCATION values('07092', 'Mountainside', 'NJ');
+insert into LOCATION values ('94118', 'San Francisco', 'CA');
+insert into LOCATION values ('10002', 'New York', 'NY');
+
+insert into VEHICLE (vin, year, make, model, trim, fk_location) values('KM8JN72DX7U587496', 2007, 'Hyundai', 'Tucson', null, '07092');
+insert into VEHICLE (vin, year, make, model, trim, fk_location) values('JTKKU4B41C1023346', 2012, 'Toyota', 'Scion', 'Xd', '94118');
+insert into VEHICLE (vin, year, make, model, trim, fk_location) values('1G1JC1444PZ215071', 2000, 'Chevrolet', 'CAVALIER VL', 'RS', '07092');

graphql/graphql-error-handling/src/test/java/com/baeldung/graphql/error/handling/GraphQLErrorHandlerApplicationIntegrationTest.java

@@ -0,0 +1,55 @@
+package com.baeldung.graphql.error.handling;
+
+import com.graphql.spring.boot.test.GraphQLResponse;
+import com.graphql.spring.boot.test.GraphQLTestTemplate;
+import org.json.JSONException;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.skyscreamer.jsonassert.JSONAssert;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import java.io.IOException;
+
+import static com.baeldung.graphql.error.handling.TestUtils.readFile;
+import static java.lang.String.format;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT, classes = GraphQLErrorHandlerApplication.class)
+public class GraphQLErrorHandlerApplicationIntegrationTest {
+
+    @Autowired
+    private GraphQLTestTemplate graphQLTestTemplate;
+
+    private static final String GRAPHQL_TEST_REQUEST_PATH = "graphql/request/%s.graphql";
+    private static final String GRAPHQL_TEST_RESPONSE_PATH = "graphql/response/%s.json";
+
+    @Test
+    public void whenUnknownOperation_thenRespondWithRequestError() throws IOException, JSONException {
+        String graphqlName = "request_error_unknown_operation";
+        GraphQLResponse actualResponse = graphQLTestTemplate.postForResource(format(GRAPHQL_TEST_REQUEST_PATH, graphqlName));
+        String expectedResponse = readFile(format(GRAPHQL_TEST_RESPONSE_PATH, graphqlName));
+
+        JSONAssert.assertEquals(expectedResponse, actualResponse.getRawResponse().getBody(), true);
+    }
+
+    @Test
+    public void whenInvalidSyntaxRequest_thenRespondWithRequestError() throws IOException, JSONException {
+        String graphqlName = "request_error_invalid_request_syntax";
+        GraphQLResponse actualResponse = graphQLTestTemplate.postForResource(format(GRAPHQL_TEST_REQUEST_PATH, graphqlName));
+        String expectedResponse = readFile(format(GRAPHQL_TEST_RESPONSE_PATH, graphqlName));
+
+        JSONAssert.assertEquals(expectedResponse, actualResponse.getRawResponse().getBody(), true);
+    }
+
+    @Test
+    public void whenRequestAllNonNullField_thenRespondPartialDataWithFieldError() throws IOException, JSONException {
+        String graphqlName = "field_error_request_non_null_fields_partial_response";
+        GraphQLResponse actualResponse = graphQLTestTemplate.postForResource(format(GRAPHQL_TEST_REQUEST_PATH, graphqlName));
+        String expectedResponse = readFile(format(GRAPHQL_TEST_RESPONSE_PATH, graphqlName));
+
+        JSONAssert.assertEquals(expectedResponse, actualResponse.getRawResponse().getBody(), true);
+    }
+}

graphql/graphql-error-handling/src/test/java/com/baeldung/graphql/error/handling/TestUtils.java

@@ -0,0 +1,15 @@
+package com.baeldung.graphql.error.handling;
+
+import org.apache.commons.io.IOUtils;
+import org.springframework.core.io.ClassPathResource;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+
+public class TestUtils {
+    public static String readFile(String path) throws IOException {
+        return IOUtils.toString(
+            new ClassPathResource(path).getInputStream(), Charset.defaultCharset()
+        );
+    }
+}

graphql/graphql-error-handling/src/test/resources/graphql/request/field_error_request_non_null_fields_partial_response.graphql

@@ -0,0 +1,10 @@
+# trim is non null but one of the record has null value for trim
+query {
+    searchAll {
+        vin
+        year
+        make
+        model
+        trim
+    }
+}

graphql/graphql-error-handling/src/test/resources/graphql/request/request_error_invalid_request_syntax.graphql

@@ -0,0 +1,9 @@
+query {
+    searchByVin(vin: "error) {
+        vin
+        year
+        make
+        model
+        trim
+    }
+}

graphql/graphql-error-handling/src/test/resources/graphql/request/request_error_unknown_operation.graphql

@@ -0,0 +1,9 @@
+subscription {
+    searchByVin(vin: "75024") {
+        vin
+        year
+        make
+        model
+        trim
+    }
+}

graphql/graphql-error-handling/src/test/resources/graphql/response/field_error_request_non_null_fields_partial_response.json

@@ -0,0 +1,34 @@
+{
+    "data": {
+        "searchAll": [
+            null,
+            {
+                "vin": "JTKKU4B41C1023346",
+                "year": 2012,
+                "make": "Toyota",
+                "model": "Scion",
+                "trim": "Xd"
+            },
+            {
+                "vin": "1G1JC1444PZ215071",
+                "year": 2000,
+                "make": "Chevrolet",
+                "model": "CAVALIER VL",
+                "trim": "RS"
+            }
+        ]
+    },
+    "errors": [
+        {
+            "message": "Cannot return null for non-nullable type: 'String' within parent 'Vehicle' (/searchAll[0]/trim)",
+            "path": [
+                "searchAll",
+                0,
+                "trim"
+            ],
+            "errorType": "DataFetchingException",
+            "locations": null,
+            "extensions": null
+        }
+    ]
+}

graphql/graphql-error-handling/src/test/resources/graphql/response/request_error_invalid_request_syntax.json

@@ -0,0 +1,18 @@
+{
+    "data": null,
+    "errors": [
+        {
+            "message": "Invalid Syntax",
+            "locations": [
+                {
+                    "line": 5,
+                    "column": 8,
+                    "sourceName": null
+                }
+            ],
+            "errorType": "InvalidSyntax",
+            "path": null,
+            "extensions": null
+        }
+    ]
+}

graphql/graphql-error-handling/src/test/resources/graphql/response/request_error_unknown_operation.json

@@ -0,0 +1,18 @@
+{
+    "data": null,
+    "errors": [
+        {
+            "errorType": "OperationNotSupported",
+            "locations": [
+                {
+                    "line": 1,
+                    "column": 1,
+                    "sourceName": null
+                }
+            ],
+            "extensions": null,
+            "message": "Schema is not configured for subscriptions.",
+            "path": null
+        }
+    ]
+}

graphql/graphql-java/pom.xml

@@ -12,7 +12,7 @@
         <groupId>com.baeldung</groupId>
         <artifactId>parent-modules</artifactId>
         <version>1.0.0-SNAPSHOT</version>
-        <relativePath>../../</relativePath>
+        <relativePath>../../pom.xml</relativePath>
     </parent>
 
     <repositories>
@@ -36,51 +36,15 @@
             <artifactId>graphql-java-annotations</artifactId>
             <version>${graphql-java-annotations.version}</version>
         </dependency>
-        <dependency>
-            <groupId>io.ratpack</groupId>
-            <artifactId>ratpack-core</artifactId>
-            <version>${ratpack-core.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>com.github.americanexpress.nodes</groupId>
-            <artifactId>nodes</artifactId>
-            <version>0.5.0</version>
-        </dependency>
-        <dependency>
-            <groupId>com.graphql-java</groupId>
-            <artifactId>graphql-java</artifactId>
-            <version>9.2</version>
-        </dependency>
         <dependency>
             <groupId>com.graphql-java</groupId>
             <artifactId>graphql-java-tools</artifactId>
-            <version>5.2.4</version>
+            <version>${graphql-java-tools.version}</version>
         </dependency>
         <dependency>
             <groupId>com.graphql-java</groupId>
             <artifactId>graphql-java-servlet</artifactId>
-            <version>6.1.3</version>
-        </dependency>
-        <dependency>
-            <groupId>javax.servlet</groupId>
-            <artifactId>javax.servlet-api</artifactId>
-            <version>3.0.1</version>
-            <scope>provided</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.apache.commons</groupId>
-            <artifactId>commons-lang3</artifactId>
-            <version>3.12.0</version>
-        </dependency>
-        <dependency>
-            <groupId>org.mock-server</groupId>
-            <artifactId>mockserver-netty</artifactId>
-            <version>5.11.2</version>
-        </dependency>
-        <dependency>
-            <groupId>org.mock-server</groupId>
-            <artifactId>mockserver-client-java</artifactId>
-            <version>5.11.2</version>
+            <version>${graphql-java-servlet.version}</version>
         </dependency>
         <dependency>
             <groupId>com.graphql-java-generator</groupId>
@@ -88,15 +52,47 @@
             <version>${graphql.java.generator.version}</version>
         </dependency>
         <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter-engine</artifactId>
-            <version>5.8.2</version>
+            <groupId>javax.servlet</groupId>
+            <artifactId>javax.servlet-api</artifactId>
+            <version>${javax.servlet-api.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-core</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.ratpack</groupId>
+            <artifactId>ratpack-core</artifactId>
+            <version>${ratpack-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.github.americanexpress.nodes</groupId>
+            <artifactId>nodes</artifactId>
+            <version>${nodes.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.httpcomponents</groupId>
+            <artifactId>httpclient</artifactId>
+            <version>${httpclient.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.mock-server</groupId>
+            <artifactId>mockserver-netty</artifactId>
+            <version>${mockserver-netty.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
-            <groupId>org.assertj</groupId>
-            <artifactId>assertj-core</artifactId>
-            <version>3.22.0</version>
+            <groupId>org.mock-server</groupId>
+            <artifactId>mockserver-client-java</artifactId>
+            <version>${mockserver-client-java.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
@@ -115,11 +111,11 @@
             <plugin>
                 <groupId>org.eclipse.jetty</groupId>
                 <artifactId>jetty-maven-plugin</artifactId>
-                <version>10.0.7</version>
+                <version>${jetty-maven-plugin.version}</version>
             </plugin>
             <plugin>
                 <artifactId>maven-war-plugin</artifactId>
-                <version>3.1.0</version>
+                <version>${maven-war-plugin.version}</version>
             </plugin>
             <plugin>
                 <groupId>com.graphql-java-generator</groupId>
@@ -143,12 +139,21 @@
     </build>
 
     <properties>
+        <graphql-java-tools.version>5.2.4</graphql-java-tools.version>
+        <graphql-java-servlet.version>6.1.3</graphql-java-servlet.version>
         <graphql-java-annotations.version>3.0.3</graphql-java-annotations.version>
-        <ratpack-core.version>1.4.6</ratpack-core.version>
-        <maven-compiler-plugin.version>3.1</maven-compiler-plugin.version>
+        <graphql.java.generator.version>1.18</graphql.java.generator.version>
+        <ratpack-core.version>1.9.0</ratpack-core.version>
+        <nodes.version>0.5.0</nodes.version>
+        <httpclient.version>4.5.13</httpclient.version>
+
+        <mockserver-netty.version>5.13.2</mockserver-netty.version>
+        <mockserver-client-java.version>5.13.2</mockserver-client-java.version>
+
+        <jetty-maven-plugin.version>10.0.7</jetty-maven-plugin.version>
+
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
-        <graphql.java.generator.version>1.18</graphql.java.generator.version>
     </properties>
 
 </project>

graphql/graphql-java/src/main/java/com/baeldung/graphql/handler/UserHandler.java

@@ -19,24 +19,27 @@ import com.baeldung.graphql.utils.SchemaUtils;
 import static ratpack.jackson.Jackson.json;
 
 public class UserHandler implements Handler {
+
     private static final Logger LOGGER = Logger.getLogger(UserHandler.class.getSimpleName());
-    private GraphQL graphql;
-    private static List<User> users = new ArrayList<>();
+
+    private static final List<User> USERS = new ArrayList<>();
+
+    private final GraphQL graphql;
 
     public UserHandler() throws Exception {
-        graphql = new GraphQL(new UserSchema().getSchema());
+        graphql = GraphQL.newGraphQL(new UserSchema().getSchema()).build();
     }
 
     @Override
-    public void handle(Context context) throws Exception {
+    public void handle(Context context) {
         context.parse(Map.class)
             .then(payload -> {
                 Map<String, Object> parameters = (Map<String, Object>) payload.get("parameters");
                 ExecutionResult executionResult = graphql.execute(payload.get(SchemaUtils.QUERY)
                     .toString(), null, this, parameters);
+
                 Map<String, Object> result = new LinkedHashMap<>();
-                if (executionResult.getErrors()
-                    .isEmpty()) {
+                if (executionResult.getErrors().isEmpty()) {
                     result.put(SchemaUtils.DATA, executionResult.getData());
                 } else {
                     result.put(SchemaUtils.ERRORS, executionResult.getErrors());
@@ -46,8 +49,8 @@ public class UserHandler implements Handler {
             });
     }
 
-    public static List<User> getUsers() {
-        return users;
+    public List<User> getUsers() {
+        return USERS;
     }
 
     public static List<User> getUsers(DataFetchingEnvironment env) {

httpclient-2/README.md

@@ -12,5 +12,6 @@ The "REST With Spring" Classes: http://bit.ly/restwithspring
 - [Reading an HTTP Response Body as a String in Java](https://www.baeldung.com/java-http-response-body-as-string)
 - [How To Get Cookies From the Apache HttpClient Response](https://www.baeldung.com/java-apache-httpclient-cookies)
 - [Enabling Logging for Apache HttpClient](https://www.baeldung.com/apache-httpclient-enable-logging)
-- [Unshorten URLs with HttpClient](https://www.baeldung.com/unshorten-url-httpclient)
+- [Expand Shortened URLs with Apache HttpClient](https://www.baeldung.com/apache-httpclient-expand-url)
+- [Apache HttpClient vs. CloseableHttpClient](https://www.baeldung.com/apache-httpclient-vs-closeablehttpclient)
 - More articles: [[<-- prev]](../httpclient)

httpclient-2/src/test/java/com/baeldung/httpclient/expandurl/HttpClientExpandUrlLiveTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.httpclient.rare;
+package com.baeldung.httpclient.expandurl;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
@@ -22,35 +22,29 @@ import java.util.List;
 import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.assertThat;
 
-public class HttpClientUnshortenLiveTest {
+public class HttpClientExpandUrlLiveTest {
 
     private CloseableHttpClient client;
 
-    // fixtures
-
     @Before
     public final void before() {
         client = HttpClientBuilder.create().disableRedirectHandling().build();
     }
 
-    // tests
-
     @Test
-    public final void givenShortenedOnce_whenUrlIsUnshortened_thenCorrectResult() throws IOException {
-        final String expectedResult = "http://www.baeldung.com/rest-versioning";
-        final String actualResult = expandSingleLevel("http://bit.ly/13jEoS1");
+    public final void givenShortenedOnce_whenUrlIsExpanded_thenCorrectResult() throws IOException {
+        final String expectedResult = "https://www.baeldung.com/rest-versioning";
+        final String actualResult = expandSingleLevel("http://bit.ly/3LScTri");
         assertThat(actualResult, equalTo(expectedResult));
     }
 
     @Test
-    public final void givenShortenedMultiple_whenUrlIsUnshortened_thenCorrectResult() throws IOException {
-        final String expectedResult = "http://www.baeldung.com/rest-versioning";
+    public final void givenShortenedMultiple_whenUrlIsExpanded_thenCorrectResult() throws IOException {
+        final String expectedResult = "https://www.baeldung.com/rest-versioning";
         final String actualResult = expand("http://t.co/e4rDDbnzmk");
         assertThat(actualResult, equalTo(expectedResult));
     }
 
-    // API
-
     private String expand(final String urlArg) throws IOException {
         String originalUrl = urlArg;
         String newUrl = expandSingleLevel(originalUrl);

immutables/README.md

@@ -1,6 +0,0 @@
-## Immutables
-
-This module contains articles about the Immutables library.
-
-### Relevant Articles:
-- [Introduction to Immutables](https://www.baeldung.com/immutables)

immutables/pom.xml

@@ -1,34 +0,0 @@
-<?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>immutables</artifactId>
-    <name>immutables</name>
-
-    <parent>
-        <groupId>com.baeldung</groupId>
-        <artifactId>parent-modules</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
-    </parent>
-
-    <dependencies>
-        <dependency>
-            <groupId>org.immutables</groupId>
-            <artifactId>value</artifactId>
-            <version>${immutables.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.mutabilitydetector</groupId>
-            <artifactId>MutabilityDetector</artifactId>
-            <version>${mutabilitydetector.version}</version>
-            <scope>test</scope>
-        </dependency>
-    </dependencies>
-
-    <properties>
-        <immutables.version>2.5.6</immutables.version>
-        <mutabilitydetector.version>0.9.6</mutabilitydetector.version>
-    </properties>
-
-</project>

jackson-modules/jackson-annotations/src/main/java/com/baeldung/jackson/deductionbasedpolymorphism/Character.java

@@ -0,0 +1,12 @@
+package com.baeldung.jackson.deductionbasedpolymorphism;
+
+import com.fasterxml.jackson.annotation.JsonSubTypes;
+import com.fasterxml.jackson.annotation.JsonSubTypes.Type;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import com.fasterxml.jackson.annotation.JsonTypeInfo.Id;
+
+@JsonTypeInfo(use = Id.DEDUCTION)
+@JsonSubTypes({ @Type(ImperialSpy.class), @Type(King.class), @Type(Knight.class) })
+public interface Character {
+
+}

jackson-modules/jackson-annotations/src/main/java/com/baeldung/jackson/deductionbasedpolymorphism/ControlledCharacter.java

@@ -0,0 +1,14 @@
+package com.baeldung.jackson.deductionbasedpolymorphism;
+
+public class ControlledCharacter {
+
+    private Character character;
+
+    public Character getCharacter() {
+        return character;
+    }
+
+    public void setCharacter(Character character) {
+        this.character = character;
+    }
+}

jackson-modules/jackson-annotations/src/main/java/com/baeldung/jackson/deductionbasedpolymorphism/ImperialSpy.java

@@ -0,0 +1,5 @@
+package com.baeldung.jackson.deductionbasedpolymorphism;
+
+public class ImperialSpy implements Character {
+
+}

jackson-modules/jackson-annotations/src/main/java/com/baeldung/jackson/deductionbasedpolymorphism/King.java

@@ -0,0 +1,14 @@
+package com.baeldung.jackson.deductionbasedpolymorphism;
+
+public class King extends NamedCharacter {
+
+    private String land;
+
+    public String getLand() {
+        return land;
+    }
+
+    public void setLand(String land) {
+        this.land = land;
+    }
+}

jackson-modules/jackson-annotations/src/main/java/com/baeldung/jackson/deductionbasedpolymorphism/Knight.java

@@ -0,0 +1,14 @@
+package com.baeldung.jackson.deductionbasedpolymorphism;
+
+public class Knight extends NamedCharacter {
+
+    private String weapon;
+
+    public String getWeapon() {
+        return weapon;
+    }
+
+    public void setWeapon(String weapon) {
+        this.weapon = weapon;
+    }
+}

jackson-modules/jackson-annotations/src/main/java/com/baeldung/jackson/deductionbasedpolymorphism/NamedCharacter.java

@@ -0,0 +1,14 @@
+package com.baeldung.jackson.deductionbasedpolymorphism;
+
+public class NamedCharacter implements Character {
+
+    private String name;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

jackson-modules/jackson-annotations/src/test/java/com/baeldung/jackson/deductionbasedpolymorphism/CaseInsensitiveInferenceUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.jackson.deductionbasedpolymorphism;
+
+import static com.baeldung.jackson.deductionbasedpolymorphism.JsonStringFormatterUtil.formatJson;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+import com.fasterxml.jackson.databind.MapperFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+
+class CaseInsensitiveInferenceUnitTest {
+
+    private final ObjectMapper objectMapper = JsonMapper.builder()
+        .configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true)
+        .build();
+
+    @Test
+    void givenACaseInsensitiveKnight_whenMapping_thenExpectKnight() throws Exception {
+        String knightJson = formatJson("{'NaMe':'Ostrava, of Boletaria', 'WeaPON':'Rune Sword'}");
+
+        Character character = objectMapper.readValue(knightJson, Character.class);
+
+        assertTrue(character instanceof Knight);
+        assertSame(character.getClass(), Knight.class);
+        Knight knight = (Knight) character;
+        assertEquals("Ostrava, of Boletaria", knight.getName());
+        assertEquals("Rune Sword", knight.getWeapon());
+    }
+
+}

jackson-modules/jackson-annotations/src/test/java/com/baeldung/jackson/deductionbasedpolymorphism/ContainedInferenceUnitTest.java

@@ -0,0 +1,73 @@
+package com.baeldung.jackson.deductionbasedpolymorphism;
+
+import static com.baeldung.jackson.deductionbasedpolymorphism.JsonStringFormatterUtil.formatJson;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+
+class ContainedInferenceUnitTest {
+
+    private final ObjectMapper objectMapper = JsonMapper.builder()
+        .build();
+
+    @Test
+    void givenAKnightControlledCharacter_whenMapping_thenExpectAControlledCharacterWithKnight() throws Exception {
+        String controlledCharacterJson = formatJson("{'character': {'name': 'Ostrava, of Boletaria', 'weapon': 'Rune Sword'}}");
+
+        ControlledCharacter controlledCharacter = objectMapper.readValue(controlledCharacterJson, ControlledCharacter.class);
+        Character character = controlledCharacter.getCharacter();
+
+        assertTrue(character instanceof Knight);
+        assertSame(character.getClass(), Knight.class);
+        Knight knight = (Knight) character;
+        assertEquals("Ostrava, of Boletaria", knight.getName());
+        assertEquals("Rune Sword", knight.getWeapon());
+    }
+
+    @Test
+    void givenAKingControlledCharacter_whenMapping_thenExpectAControlledCharacterWithKing() throws Exception {
+        String controlledCharacterJson = formatJson("{'character': {'name': 'King Allant', 'land': 'Boletaria'}}");
+
+        ControlledCharacter controlledCharacter = objectMapper.readValue(controlledCharacterJson, ControlledCharacter.class);
+        Character character = controlledCharacter.getCharacter();
+
+        assertTrue(character instanceof King);
+        assertSame(character.getClass(), King.class);
+        King king = (King) character;
+        assertEquals("King Allant", king.getName());
+        assertEquals("Boletaria", king.getLand());
+    }
+
+    @Test
+    void givenAnEmptySubtype_whenMapping_thenExpectImperialSpy() throws Exception {
+        String controlledCharacterJson = formatJson("{'character': {}}");
+
+        ControlledCharacter controlledCharacter = objectMapper.readValue(controlledCharacterJson, ControlledCharacter.class);
+
+        assertTrue(controlledCharacter.getCharacter() instanceof ImperialSpy);
+    }
+
+    @Test
+    void givenANullCharacter_whenMapping_thenExpectNullCharacter() throws Exception {
+        String controlledCharacterJson = formatJson("{'character': null}");
+
+        ControlledCharacter controlledCharacter = objectMapper.readValue(controlledCharacterJson, ControlledCharacter.class);
+
+        assertNull(controlledCharacter.getCharacter());
+    }
+
+    @Test
+    void givenAAnAbsentCharacter_whenMapping_thenExpectNullCharacter() throws Exception {
+        String controlledCharacterJson = formatJson("{}");
+
+        ControlledCharacter controlledCharacter = objectMapper.readValue(controlledCharacterJson, ControlledCharacter.class);
+
+        assertNull(controlledCharacter.getCharacter());
+    }
+}

jackson-modules/jackson-annotations/src/test/java/com/baeldung/jackson/deductionbasedpolymorphism/JsonStringFormatterUtil.java

@@ -0,0 +1,9 @@
+package com.baeldung.jackson.deductionbasedpolymorphism;
+
+public class JsonStringFormatterUtil {
+
+    public static String formatJson(String input) {
+        return input.replaceAll("'", "\"");
+    }
+
+}

jackson-modules/jackson-annotations/src/test/java/com/baeldung/jackson/deductionbasedpolymorphism/SimpleInferenceUnitTest.java

@@ -0,0 +1,61 @@
+package com.baeldung.jackson.deductionbasedpolymorphism;
+
+import static com.baeldung.jackson.deductionbasedpolymorphism.JsonStringFormatterUtil.formatJson;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+
+class SimpleInferenceUnitTest {
+
+    private final ObjectMapper objectMapper = JsonMapper.builder()
+        .build();
+
+    @Test
+    void givenAKnight_whenMapping_thenExpectAKnightType() throws Exception {
+        String knightJson = formatJson("{'name':'Ostrava, of Boletaria', 'weapon':'Rune Sword'}");
+
+        Character character = objectMapper.readValue(knightJson, Character.class);
+
+        assertTrue(character instanceof Knight);
+        assertSame(character.getClass(), Knight.class);
+        Knight king = (Knight) character;
+        assertEquals("Ostrava, of Boletaria", king.getName());
+        assertEquals("Rune Sword", king.getWeapon());
+    }
+
+    @Test
+    void givenAKing_whenMapping_thenExpectAKingType() throws Exception {
+        String kingJson = formatJson("{'name':'Old King Allant', 'land':'Boletaria'}");
+
+        Character character = objectMapper.readValue(kingJson, Character.class);
+
+        assertTrue(character instanceof King);
+        assertSame(character.getClass(), King.class);
+        King king = (King) character;
+        assertEquals("Old King Allant", king.getName());
+        assertEquals("Boletaria", king.getLand());
+    }
+
+    @Test
+    void givenAnEmptyObject_whenMapping_thenExpectAnImperialSpy() throws Exception {
+        String imperialSpyJson = "{}";
+
+        Character character = objectMapper.readValue(imperialSpyJson, Character.class);
+
+        assertTrue(character instanceof ImperialSpy);
+    }
+
+    @Test
+    void givenANullObject_whenMapping_thenExpectANullObject() throws Exception {
+        Character character = objectMapper.readValue("null", Character.class);
+
+        assertNull(character);
+    }
+
+}

java-numbers-4/README.md

@@ -5,3 +5,4 @@
 - [Determine if an Integer’s Square Root Is an Integer in Java](https://www.baeldung.com/java-find-if-square-root-is-integer)
 - [Guide to Java BigInteger](https://www.baeldung.com/java-biginteger)
 - [Automorphic Numbers in Java](https://www.baeldung.com/java-automorphic-numbers)
+- [Convert Byte Size Into a Human-Readable Format in Java](https://www.baeldung.com/java-human-readable-byte-size)

jmeter/README.md

@@ -53,3 +53,4 @@ Enjoy it :)
 - [Intro to Performance Testing using JMeter](https://www.baeldung.com/jmeter)
 - [Configure Jenkins to Run and Show JMeter Tests](https://www.baeldung.com/ops/jenkins-and-jmeter)
 - [Write Extracted Data to a File Using JMeter](https://www.baeldung.com/jmeter-write-to-file)
+- [Basic Authentication in JMeter](https://www.baeldung.com/jmeter-basic-auth)

libraries-3/README.md

@@ -17,4 +17,5 @@ Remember, for advanced libraries like [Jackson](/jackson) and [JUnit](/testing-m
 - [Using NullAway to Avoid NullPointerExceptions](https://www.baeldung.com/java-nullaway)
 - [Introduction to Alibaba Arthas](https://www.baeldung.com/java-alibaba-arthas-intro)
 - [Introduction to Structurizr](https://www.baeldung.com/structurizr)
+- [Introduction to Immutables](https://www.baeldung.com/immutables)
 - More articles [[<-- prev]](../libraries-2) [[next -->]](../libraries-4)

libraries-3/pom.xml

@@ -112,6 +112,17 @@
             <artifactId>structurizr-plantuml</artifactId>
             <version>${structurizr.version}</version>
         </dependency>
+         <dependency>
+            <groupId>org.immutables</groupId>
+            <artifactId>value</artifactId>
+            <version>${immutables.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.mutabilitydetector</groupId>
+            <artifactId>MutabilityDetector</artifactId>
+            <version>${mutabilitydetector.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <repositories>
@@ -256,6 +267,8 @@
         <plexus-compiler.version>2.8</plexus-compiler.version>
         <errorprone.version>2.1.3</errorprone.version>
         <structurizr.version>1.0.0</structurizr.version>
+        <immutables.version>2.5.6</immutables.version>
+        <mutabilitydetector.version>0.9.6</mutabilitydetector.version>
     </properties>
 
 </project>

persistence-modules/hibernate-annotations/pom.xml

@@ -82,7 +82,7 @@
         <!-- Spring -->
         <org.springframework.version>5.0.2.RELEASE</org.springframework.version>
         <org.springframework.data.version>1.10.6.RELEASE</org.springframework.data.version>
-        <hibernate-core.version>5.4.7.Final</hibernate-core.version>
+        <hibernate-core.version>5.6.7.Final</hibernate-core.version>
         <maven.deploy.skip>true</maven.deploy.skip>
         <spring-boot.version>2.1.7.RELEASE</spring-boot.version>
         <h2.version>1.4.200</h2.version>

persistence-modules/hibernate-annotations/src/main/java/com/baeldung/hibernate/oneToMany/config/HibernateAnnotationUtil.java

@@ -1,34 +1,51 @@
 package com.baeldung.hibernate.oneToMany.config;
 
+import com.baeldung.hibernate.oneToMany.model.Cart;
+import com.baeldung.hibernate.oneToMany.model.CartOIO;
+import com.baeldung.hibernate.oneToMany.model.Item;
+import com.baeldung.hibernate.oneToMany.model.ItemOIO;
 import org.hibernate.SessionFactory;
 import org.hibernate.boot.Metadata;
 import org.hibernate.boot.MetadataSources;
+import org.hibernate.boot.model.naming.ImplicitNamingStrategyJpaCompliantImpl;
 import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
 import org.hibernate.service.ServiceRegistry;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class HibernateAnnotationUtil {
 
+    private static final Logger LOGGER = LoggerFactory.getLogger(HibernateAnnotationUtil.class);
+
     private static SessionFactory sessionFactory;
 
+    public static SessionFactory getSessionFactory() {
+        if (sessionFactory == null) {
+            sessionFactory = buildSessionFactory();
+        }
+        return sessionFactory;
+    }
+
     private static SessionFactory buildSessionFactory() {
         try {
-            // Create the SessionFactory from hibernate-annotation.cfg.xml
-            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().configure("hibernate-annotation.cfg.xml").build();
-            Metadata metadata = new MetadataSources(serviceRegistry).getMetadataBuilder().build();
-            SessionFactory sessionFactory = metadata.getSessionFactoryBuilder().build();
+            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
+              .configure("hibernate-annotation.cfg.xml")
+              .build();
 
-            return sessionFactory;
+            Metadata metadata = new MetadataSources(serviceRegistry)
+              .addAnnotatedClass(Cart.class)
+              .addAnnotatedClass(CartOIO.class)
+              .addAnnotatedClass(Item.class)
+              .addAnnotatedClass(ItemOIO.class)
+              .getMetadataBuilder()
+              .applyImplicitNamingStrategy(ImplicitNamingStrategyJpaCompliantImpl.INSTANCE)
+              .build();
+
+            return metadata.getSessionFactoryBuilder().build();
 
         } catch (Throwable ex) {
-            System.err.println("Initial SessionFactory creation failed." + ex);
-            ex.printStackTrace();
+            LOGGER.error("Initial SessionFactory creation failed.", ex);
             throw new ExceptionInInitializerError(ex);
         }
     }
-
-    public static SessionFactory getSessionFactory() {
-        if (sessionFactory == null)
-            sessionFactory = buildSessionFactory();
-        return sessionFactory;
-    }
 }

persistence-modules/hibernate-annotations/src/main/java/com/baeldung/hibernate/oneToMany/main/HibernateManyIsOwningSide.java

@@ -0,0 +1,71 @@
+package com.baeldung.hibernate.oneToMany.main;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.Transaction;
+
+import com.baeldung.hibernate.oneToMany.config.HibernateAnnotationUtil;
+import com.baeldung.hibernate.oneToMany.model.Cart;
+import com.baeldung.hibernate.oneToMany.model.Item;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class HibernateManyIsOwningSide {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(HibernateManyIsOwningSide.class);
+
+    public static void main(String[] args) {
+
+        Cart cart = new Cart();
+        Cart cart2 = new Cart();
+
+        Item item1 = new Item(cart);
+        Item item2 = new Item(cart2);
+
+        Set<Item> itemsSet = new HashSet<>();
+        itemsSet.add(item1);
+        itemsSet.add(item2);
+        cart.setItems(itemsSet);
+
+        // Get Session
+        SessionFactory sessionFactory = HibernateAnnotationUtil.getSessionFactory();
+        Session session = sessionFactory.getCurrentSession();
+
+        try {
+            LOGGER.info("Session created");
+
+            // start transaction
+            Transaction tx = session.beginTransaction();
+
+            // Save the Model object
+            session.save(cart);
+            session.save(cart2);
+            session.save(item1);
+            session.save(item2);
+
+            // Commit transaction
+            tx.commit();
+
+            session = sessionFactory.getCurrentSession();
+            tx = session.beginTransaction();
+
+            item1 = session.get(Item.class, 1L);
+            item2 = session.get(Item.class, 2L);
+            tx.commit();
+
+            LOGGER.info("item1 ID={}, Foreign Key CartOIO ID={}", item1.getId(), item1.getCart().getId());
+            LOGGER.info("item2 ID={}, Foreign Key CartOIO ID={}", item2.getId(), item2.getCart().getId());
+
+        } catch (Exception e) {
+            LOGGER.error("Exception occurred", e);
+        } finally {
+            if (!sessionFactory.isClosed()) {
+                LOGGER.info("Closing SessionFactory");
+                sessionFactory.close();
+            }
+        }
+    }
+}

persistence-modules/hibernate-annotations/src/main/java/com/baeldung/hibernate/oneToMany/main/HibernateManyisOwningSide.java

@@ -1,71 +0,0 @@
-package com.baeldung.hibernate.oneToMany.main;
-
-import java.util.HashSet;
-import java.util.Set;
-
-import org.hibernate.Session;
-import org.hibernate.SessionFactory;
-import org.hibernate.Transaction;
-
-import com.baeldung.hibernate.oneToMany.config.HibernateAnnotationUtil;
-import com.baeldung.hibernate.oneToMany.model.Cart;
-import com.baeldung.hibernate.oneToMany.model.Items;
-import com.baeldung.hibernate.oneToMany.model.ItemsOIO;
-
-public class HibernateManyisOwningSide {
-    public static void main(String[] args) {
-
-        Cart cart = new Cart();
-        Cart cart2 = new Cart();
-
-        Items item1 = new Items(cart);
-        Items item2 = new Items(cart2);
-        Set<Items> itemsSet = new HashSet<Items>();
-        itemsSet.add(item1);
-        itemsSet.add(item2);
-
-        cart.setItems(itemsSet);
-
-        
-        
-        SessionFactory sessionFactory = null;
-        Session session = null;
-        Transaction tx = null;
-        try {
-            // Get Session
-            sessionFactory = HibernateAnnotationUtil.getSessionFactory();
-            session = sessionFactory.getCurrentSession();
-            System.out.println("Session created");
-            // start transaction
-            tx = session.beginTransaction();
-            // Save the Model object
-            session.save(cart);
-            session.save(cart2);
-            session.save(item1);
-            session.save(item2);
-            // Commit transaction
-            tx.commit();
-            session = sessionFactory.getCurrentSession();
-            tx = session.beginTransaction();
-
-            item1 = (Items) session.get(Items.class, new Long(1));
-            item2 = (Items) session.get(Items.class, new Long(2));
-            tx.commit();
-            
-         
-            System.out.println("item1 ID=" + item1.getId() + ", Foreign Key CartOIO ID=" + item1.getCart()
-                .getId());
-            System.out.println("item2 ID=" + item2.getId() + ", Foreign Key CartOIO ID=" + item2.getCart()
-                .getId());
-
-        } catch (Exception e) {
-            System.out.println("Exception occured. " + e.getMessage());
-            e.printStackTrace();
-        } finally {
-            if (!sessionFactory.isClosed()) {
-                System.out.println("Closing SessionFactory");
-                sessionFactory.close();
-            }
-        }
-    }
-}

persistence-modules/hibernate-annotations/src/main/java/com/baeldung/hibernate/oneToMany/main/HibernateOneIsOwningSide.java

@@ -9,57 +9,59 @@ import org.hibernate.Transaction;
 
 import com.baeldung.hibernate.oneToMany.config.HibernateAnnotationUtil;
 import com.baeldung.hibernate.oneToMany.model.CartOIO;
-import com.baeldung.hibernate.oneToMany.model.ItemsOIO;
+import com.baeldung.hibernate.oneToMany.model.ItemOIO;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class HibernateOneIsOwningSide {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(HibernateOneIsOwningSide.class);
 
-public class HibernateOneisOwningSide {
     public static void main(String[] args) {
 
         CartOIO cart = new CartOIO();
         CartOIO cart2 = new CartOIO();
 
-        ItemsOIO item1 = new ItemsOIO(cart);
-        ItemsOIO item2 = new ItemsOIO(cart2);
-        Set<ItemsOIO> itemsSet = new HashSet<ItemsOIO>();
+        ItemOIO item1 = new ItemOIO(cart);
+        ItemOIO item2 = new ItemOIO(cart2);
+        Set<ItemOIO> itemsSet = new HashSet<>();
         itemsSet.add(item1);
         itemsSet.add(item2);
 
         cart.setItems(itemsSet);
 
-        SessionFactory sessionFactory = null;
-        Session session = null;
-        Transaction tx = null;
+        SessionFactory sessionFactory = HibernateAnnotationUtil.getSessionFactory();
+        Session session = sessionFactory.getCurrentSession();
+        LOGGER.info("Session created");
+
+        Transaction tx;
         try {
-            // Get Session
-            sessionFactory = HibernateAnnotationUtil.getSessionFactory();
-            session = sessionFactory.getCurrentSession();
-            System.out.println("Session created");
             // start transaction
             tx = session.beginTransaction();
+
             // Save the Model object
             session.save(cart);
             session.save(cart2);
             session.save(item1);
             session.save(item2);
+
             // Commit transaction
             tx.commit();
 
             session = sessionFactory.getCurrentSession();
             tx = session.beginTransaction();
-            item1 = (ItemsOIO) session.get(ItemsOIO.class, new Long(1));
-            item2 = (ItemsOIO) session.get(ItemsOIO.class, new Long(2));
+            item1 = session.get(ItemOIO.class, 1L);
+            item2 = session.get(ItemOIO.class, 2L);
             tx.commit();
 
-            System.out.println("item1 ID=" + item1.getId() + ", Foreign Key CartOIO ID=" + item1.getCartOIO()
-                .getId());
-            System.out.println("item2 ID=" + item2.getId() + ", Foreign Key CartOIO ID=" + item2.getCartOIO()
-                .getId());
+            LOGGER.info("item1 ID={}, Foreign Key CartOIO ID={}", item1.getId(), item1.getCartOIO().getId());
+            LOGGER.info("item2 ID={}, Foreign Key CartOIO ID={}", item2.getId(), item2.getCartOIO().getId());
 
         } catch (Exception e) {
-            System.out.println("Exception occured. " + e.getMessage());
-            e.printStackTrace();
+            LOGGER.error("Exception occurred", e);
         } finally {
             if (!sessionFactory.isClosed()) {
-                System.out.println("Closing SessionFactory");
+                LOGGER.info("Closing SessionFactory");
                 sessionFactory.close();
             }
         }

persistence-modules/hibernate-annotations/src/main/java/com/baeldung/hibernate/oneToMany/main/HibernateOneToManyAnnotationMain.java

@@ -9,52 +9,53 @@ import org.hibernate.Transaction;
 
 import com.baeldung.hibernate.oneToMany.config.HibernateAnnotationUtil;
 import com.baeldung.hibernate.oneToMany.model.Cart;
-import com.baeldung.hibernate.oneToMany.model.Items;
+import com.baeldung.hibernate.oneToMany.model.Item;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class HibernateOneToManyAnnotationMain {
 
+    private static final Logger LOGGER = LoggerFactory.getLogger(HibernateOneToManyAnnotationMain.class);
+
     public static void main(String[] args) {
 
         Cart cart = new Cart();
 
-        Items item1 = new Items(cart);
-        Items item2 = new Items(cart);
-        Set<Items> itemsSet = new HashSet<Items>();
+        Item item1 = new Item(cart);
+        Item item2 = new Item(cart);
+        Set<Item> itemsSet = new HashSet<>();
         itemsSet.add(item1);
         itemsSet.add(item2);
 
         cart.setItems(itemsSet);
-        
 
-        SessionFactory sessionFactory = null;
-        Session session = null;
-        Transaction tx = null;
+        SessionFactory sessionFactory = HibernateAnnotationUtil.getSessionFactory();
+        Session session = sessionFactory.getCurrentSession();
+        LOGGER.info("Session created");
+
         try {
-            // Get Session
-            sessionFactory = HibernateAnnotationUtil.getSessionFactory();
-            session = sessionFactory.getCurrentSession();
-            System.out.println("Session created");
             // start transaction
-            tx = session.beginTransaction();
+            Transaction tx = session.beginTransaction();
+
             // Save the Model object
             session.save(cart);
             session.save(item1);
             session.save(item2);
+
             // Commit transaction
             tx.commit();
-            System.out.println("Cart ID=" + cart.getId());
-            System.out.println("item1 ID=" + item1.getId() + ", Foreign Key Cart ID=" + item1.getCart().getId());
-            System.out.println("item2 ID=" + item2.getId() + ", Foreign Key Cart ID=" + item1.getCart().getId());
+
+            LOGGER.info("Cart ID={}", cart.getId());
+            LOGGER.info("item1 ID={}, Foreign Key Cart ID={}", item1.getId(), item1.getCart().getId());
+            LOGGER.info("item2 ID={}, Foreign Key Cart ID={}", item2.getId(), item2.getCart().getId());
 
         } catch (Exception e) {
-            System.out.println("Exception occured. " + e.getMessage());
-            e.printStackTrace();
+            LOGGER.error("Exception occurred", e);
         } finally {
             if (!sessionFactory.isClosed()) {
-                System.out.println("Closing SessionFactory");
+                LOGGER.info("Closing SessionFactory");
                 sessionFactory.close();
             }
         }
     }
-
 }

persistence-modules/hibernate-annotations/src/main/java/com/baeldung/hibernate/oneToMany/model/Cart.java

@@ -19,9 +19,8 @@ public class Cart {
     @Column(name = "cart_id")
     private long id;
 
-
     @OneToMany(mappedBy = "cart")
-    private Set<Items> items;
+    private Set<Item> items;
 
     public long getId() {
         return id;
@@ -31,12 +30,11 @@ public class Cart {
         this.id = id;
     }
 
-
-    public Set<Items> getItems() {
+    public Set<Item> getItems() {
         return items;
     }
 
-    public void setItems(Set<Items> items) {
+    public void setItems(Set<Item> items) {
         this.items = items;
     }
 

persistence-modules/hibernate-annotations/src/main/java/com/baeldung/hibernate/oneToMany/model/CartOIO.java

@@ -9,8 +9,6 @@ import javax.persistence.JoinColumn;
 import javax.persistence.OneToMany;
 import javax.persistence.Table;
 
-
-
 @Entity
 @Table(name = "CARTOIO")
 public class CartOIO {
@@ -21,7 +19,7 @@ public class CartOIO {
 
     @OneToMany
     @JoinColumn(name = "cart_id") // we need to duplicate the physical information
-    private Set<ItemsOIO> items;
+    private Set<ItemOIO> items;
 
     public long getId() {
         return id;
@@ -31,11 +29,11 @@ public class CartOIO {
         this.id = id;
     }
 
-    public Set<ItemsOIO> getItems() {
+    public Set<ItemOIO> getItems() {
         return items;
     }
 
-    public void setItems(Set<ItemsOIO> items) {
+    public void setItems(Set<ItemOIO> items) {
         this.items = items;
     }