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

animal-sniffer-mvn-plugin/pom.xml

@@ -9,7 +9,7 @@
   <url>http://maven.apache.org</url>
   
   <properties>
-        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>	
+        <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>	
     </properties>
 	
   <dependencies>
@@ -26,8 +26,8 @@
 				  <artifactId>maven-compiler-plugin</artifactId>
 				  <version>3.7.0</version>
 				  <configuration>
-					<source>1.6</source>
+					<source>1.8</source>
-					<target>1.6</target>
+					<target>1.8</target>
 				  </configuration>
 				</plugin>
 				<plugin>

annotations/annotation-processing/pom.xml

@@ -15,7 +15,7 @@
 
     <properties>
         <auto-service.version>1.0-rc2</auto-service.version>
-        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+        <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
     </properties>
 
     <dependencies>

apache-shiro/pom.xml

@@ -65,7 +65,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.6.2</version>
+                <version>3.7.0</version>
                 <configuration>
                     <source>1.8</source>
                     <target>1.8</target>

camel-api/pom.xml

@@ -12,7 +12,7 @@
 
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-		<maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+		<maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
 		<maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
 		<camel.version>2.19.1</camel.version>
 	    <spring-boot-starter.version>1.5.4.RELEASE</spring-boot-starter.version>

cas/cas-server/pom.xml

@@ -52,7 +52,11 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.3</version>
+                <version>3.7.0</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
             </plugin>
         </plugins>
         <finalName>cas</finalName>

core-java-8/README.md

@@ -33,3 +33,4 @@
 - [Display All Time Zones With GMT And UTC in Java](http://www.baeldung.com/java-time-zones)
 - [Copy a File with Java](http://www.baeldung.com/java-copy-file)
 - [Generating Prime Numbers in Java](http://www.baeldung.com/java-generate-prime-numbers)
+- [Static and Default Methods in Interfaces in Java](http://www.baeldung.com/java-static-default-methods)

core-java-8/src/main/java/com/baeldung/datetime/UseDuration.java

@@ -2,7 +2,6 @@ package com.baeldung.datetime;
 
 import java.time.Duration;
 import java.time.LocalTime;
-import java.time.Period;
 
 public class UseDuration {
 

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/application/Application.java

@@ -0,0 +1,18 @@
+package com.baeldung.defaultstaticinterfacemethods.application;
+
+import com.baeldung.defaultstaticinterfacemethods.model.Car;
+import com.baeldung.defaultstaticinterfacemethods.model.Vehicle;
+
+public class Application {
+
+    public static void main(String[] args) {
+
+        Vehicle car = new Car("BMW");
+        System.out.println(car.getBrand());
+        System.out.println(car.speedUp());
+        System.out.println(car.slowDown());
+        System.out.println(car.turnAlarmOn());
+        System.out.println(car.turnAlarmOff());
+        System.out.println(Vehicle.getHorsePower(2500, 480));
+    }
+}

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Alarm.java

@@ -0,0 +1,12 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public interface Alarm {
+
+    default String turnAlarmOn() {
+        return "Turning the alarm on.";
+    }
+
+    default String turnAlarmOff() {
+        return "Turning the alarm off.";
+    }
+}

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Car.java

@@ -0,0 +1,25 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public class Car implements Vehicle {
+
+    private final String brand;
+
+    public Car(String brand) {
+        this.brand = brand;
+    }
+
+    @Override
+    public String getBrand() {
+        return brand;
+    }
+
+    @Override
+    public String speedUp() {
+        return "The car is speeding up.";
+    }
+
+    @Override
+    public String slowDown() {
+        return "The car is slowing down.";
+    }
+}

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Motorbike.java

@@ -0,0 +1,25 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public class Motorbike implements Vehicle {
+
+    private final String brand;
+
+    public Motorbike(String brand) {
+        this.brand = brand;
+    }
+
+    @Override
+    public String getBrand() {
+        return brand;
+    }
+
+    @Override
+    public String speedUp() {
+        return "The motorbike is speeding up.";
+    }
+
+    @Override
+    public String slowDown() {
+        return "The motorbike is slowing down.";
+    }
+}

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/MultiAlarmCar.java

@@ -0,0 +1,35 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public class MultiAlarmCar implements Vehicle, Alarm {
+
+    private final String brand;
+
+    public MultiAlarmCar(String brand) {
+        this.brand = brand;
+    }
+
+    @Override
+    public String getBrand() {
+        return brand;
+    }
+
+    @Override
+    public String speedUp() {
+        return "The motorbike is speeding up.";
+    }
+
+    @Override
+    public String slowDown() {
+        return "The mootorbike is slowing down.";
+    }
+
+    @Override
+    public String turnAlarmOn() {
+        return Vehicle.super.turnAlarmOn() + " " + Alarm.super.turnAlarmOn();
+    }
+
+    @Override
+    public String turnAlarmOff() {
+        return Vehicle.super.turnAlarmOff() + " " + Alarm.super.turnAlarmOff();
+    }
+}

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Vehicle.java

@@ -0,0 +1,22 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public interface Vehicle {
+
+    String getBrand();
+
+    String speedUp();
+
+    String slowDown();
+
+    default String turnAlarmOn() {
+        return "Turning the vehice alarm on.";
+    }
+
+    default String turnAlarmOff() {
+        return "Turning the vehicle alarm off.";
+    }
+
+    static int getHorsePower(int rpm, int torque) {
+        return (rpm * torque) / 5252;
+    }
+}

core-java-8/src/main/java/com/baeldung/iterators/Iterators.java

@@ -0,0 +1,80 @@
+package com.baeldung.iterators;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Source code https://github.com/eugenp/tutorials
+ *
+ * @author Santosh Thakur
+ */
+
+public class Iterators {
+
+    public static int failFast1() {
+        ArrayList<Integer> numbers = new ArrayList<>();
+
+        numbers.add(10);
+        numbers.add(20);
+        numbers.add(30);
+        numbers.add(40);
+
+        Iterator<Integer> iterator = numbers.iterator();
+        while (iterator.hasNext()) {
+            Integer number = iterator.next();
+            numbers.add(50);
+        }
+
+        return numbers.size();
+    }
+
+    public static int failFast2() {
+        ArrayList<Integer> numbers = new ArrayList<>();
+        numbers.add(10);
+        numbers.add(20);
+        numbers.add(30);
+        numbers.add(40);
+
+        Iterator<Integer> iterator = numbers.iterator();
+        while (iterator.hasNext()) {
+            if (iterator.next() == 30) {
+                // will not throw Exception
+                iterator.remove();
+            }
+        }
+
+        System.out.println("using iterator's remove method = " + numbers);
+
+        iterator = numbers.iterator();
+        while (iterator.hasNext()) {
+            if (iterator.next() == 40) {
+                // will throw Exception on
+                // next call of next() method
+                numbers.remove(2);
+            }
+        }
+
+        return numbers.size();
+    }
+
+    public static int failSafe1() {
+        ConcurrentHashMap<String, Integer> map = new ConcurrentHashMap<>();
+
+        map.put("First", 10);
+        map.put("Second", 20);
+        map.put("Third", 30);
+        map.put("Fourth", 40);
+
+        Iterator<String> iterator = map.keySet()
+            .iterator();
+
+        while (iterator.hasNext()) {
+            String key = iterator.next();
+            map.put("Fifth", 50);
+        }
+
+        return map.size();
+    }
+
+}

core-java-8/src/main/java/com/baeldung/streamApi/Product.java

@@ -1,8 +1,6 @@
 package com.baeldung.streamApi;
 
 import java.util.List;
-import java.util.Optional;
-import java.util.stream.IntStream;
 import java.util.stream.Stream;
 
 /**

core-java-8/src/test/java/com/baeldung/counter/CounterStatistics.java

@@ -2,6 +2,7 @@ package com.baeldung.counter;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Random;
 
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.BenchmarkMode;
@@ -18,6 +19,16 @@ public class CounterStatistics {
     private static final Map<String, MutableInteger> counterWithMutableIntMap = new HashMap<>();
     private static final Map<String, int[]> counterWithIntArrayMap = new HashMap<>();
     private static final Map<String, Long> counterWithLongWrapperMap = new HashMap<>();
+    private static final Map<String, Long> counterWithLongWrapperStreamMap = new HashMap<>();
+    
+    static {
+        CounterUtil.COUNTRY_NAMES = new String[10000];
+        final String prefix = "NewString"; 
+        Random random = new Random();
+        for (int i=0; i<10000; i++) {
+            CounterUtil.COUNTRY_NAMES[i] = new String(prefix + random.nextInt(1000));
+        }
+    }
 
   @Benchmark
     public void wrapperAsCounter() {
@@ -29,6 +40,11 @@ public class CounterStatistics {
         CounterUtil.counterWithLambdaAndWrapper(counterWithLongWrapperMap);
     }
     
+    @Benchmark
+    public void parallelStreamWithWrapper() {
+        CounterUtil.counterWithParallelStreamAndWrapper(counterWithLongWrapperStreamMap);
+    }
+
     @Benchmark
     public void mutableIntegerAsCounter() {
         CounterUtil.counterWithMutableInteger(counterWithMutableIntMap);

core-java-8/src/test/java/com/baeldung/counter/CounterUtil.java

@@ -6,7 +6,7 @@ import java.util.stream.Stream;
 
 public class CounterUtil {
 
-    private final static String[] COUNTRY_NAMES = { "China", "Australia", "India", "USA", "USSR", "UK", "China", "France", "Poland", "Austria", "India", "USA", "Egypt", "China" };
+    public static String[] COUNTRY_NAMES = { "China", "Australia", "India", "USA", "USSR", "UK", "China", "France", "Poland", "Austria", "India", "USA", "Egypt", "China" };
 
     public static void counterWithWrapperObject(Map<String, Integer> counterMap) {
         for (String country : COUNTRY_NAMES) {
@@ -15,9 +15,14 @@ public class CounterUtil {
     }
 
     public static void counterWithLambdaAndWrapper(Map<String, Long> counterMap) {
-        counterMap.putAll(Stream.of(COUNTRY_NAMES)
+        Stream.of(COUNTRY_NAMES)
+            .collect(Collectors.groupingBy(k -> k, () -> counterMap, Collectors.counting()));
+    }
+
+    public static void counterWithParallelStreamAndWrapper(Map<String, Long> counterMap) {
+        Stream.of(COUNTRY_NAMES)
             .parallel()
-            .collect(Collectors.groupingBy(k -> k, Collectors.counting())));
+            .collect(Collectors.groupingBy(k -> k, () -> counterMap, Collectors.counting()));
     }
 
     public static class MutableInteger {

core-java-8/src/test/java/com/baeldung/datetime/UseLocalDateTimeUnitTest.java

@@ -4,7 +4,6 @@ import java.time.LocalDate;
 import java.time.LocalTime;
 import java.time.Month;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;

core-java-8/src/test/java/com/baeldung/datetime/UseLocalDateUnitTest.java

@@ -4,7 +4,6 @@ import java.time.DayOfWeek;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;

core-java-8/src/test/java/com/baeldung/defaultistaticinterfacemethods/test/StaticDefaulInterfaceMethodUnitTest.java

@@ -0,0 +1,79 @@
+package com.baeldung.defaultistaticinterfacemethods.test;
+
+import com.baeldung.defaultstaticinterfacemethods.model.Car;
+import com.baeldung.defaultstaticinterfacemethods.model.Motorbike;
+import com.baeldung.defaultstaticinterfacemethods.model.Vehicle;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class StaticDefaulInterfaceMethodUnitTest {
+
+    private static Car car;
+    private static Motorbike motorbike;
+
+    @BeforeClass
+    public static void setUpCarInstance() {
+        car = new Car("BMW");
+    }
+
+    @BeforeClass
+    public static void setUpMotorbikeInstance() {
+        motorbike = new Motorbike("Yamaha");
+    }
+
+    @Test
+    public void givenCarInstace_whenBrandisBMW_thenOneAssertion() {
+        assertThat(car.getBrand()).isEqualTo("BMW");
+    }
+
+    @Test
+    public void givenCarInstance_whenCallingSpeedUp_thenOneAssertion() {
+        assertThat(car.speedUp()).isEqualTo("The car is speeding up.");
+    }
+
+    @Test
+    public void givenCarInstance_whenCallingSlowDown_thenOneAssertion() {
+        assertThat(car.slowDown()).isEqualTo("The car is slowing down.");
+    }
+
+    @Test
+    public void givenCarInstance_whenCallingTurnAlarmOn_thenOneAssertion() {
+        assertThat(car.turnAlarmOn()).isEqualTo("Turning the vehice alarm on.");
+    }
+
+    @Test
+    public void givenCarInstance_whenCallingTurnAlarmOff_thenOneAssertion() {
+        assertThat(car.turnAlarmOff()).isEqualTo("Turning the vehicle alarm off.");
+    }
+
+    @Test
+    public void givenVehicleInterface_whenCallinggetHorsePower_thenOneAssertion() {
+        assertThat(Vehicle.getHorsePower(2500, 480)).isEqualTo(228);
+    }
+
+    @Test
+    public void givenMooorbikeInstace_whenBrandisYamaha_thenOneAssertion() {
+        assertThat(motorbike.getBrand()).isEqualTo("Yamaha");
+    }
+
+    @Test
+    public void givenMotorbikeInstance_whenCallingSpeedUp_thenOneAssertion() {
+        assertThat(motorbike.speedUp()).isEqualTo("The motorbike is speeding up.");
+    }
+
+    @Test
+    public void givenMotorbikeInstance_whenCallingSlowDown_thenOneAssertion() {
+        assertThat(motorbike.slowDown()).isEqualTo("The motorbike is slowing down.");
+    }
+
+    @Test
+    public void givenMotorbikeInstance_whenCallingTurnAlarmOn_thenOneAssertion() {
+        assertThat(motorbike.turnAlarmOn()).isEqualTo("Turning the vehice alarm on.");
+    }
+
+    @Test
+    public void givenMotorbikeInstance_whenCallingTurnAlarmOff_thenOneAssertion() {
+        assertThat(motorbike.turnAlarmOff()).isEqualTo("Turning the vehicle alarm off.");
+    }
+}

core-java-8/src/test/java/com/baeldung/iterators/IteratorsTest.java

@@ -0,0 +1,40 @@
+package com.baeldung.iterators;
+
+import static com.baeldung.iterators.Iterators.failFast1;
+import static com.baeldung.iterators.Iterators.failFast2;
+import static com.baeldung.iterators.Iterators.failSafe1;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import java.util.ConcurrentModificationException;
+
+import org.junit.Test;
+
+/**
+ * Source code https://github.com/eugenp/tutorials
+ *
+ * @author Santosh Thakur
+ */
+
+public class IteratorsTest {
+
+    @Test
+    public void whenFailFast_ThenThrowsException() {
+        assertThatThrownBy(() -> {
+            failFast1();
+        }).isInstanceOf(ConcurrentModificationException.class);
+    }
+
+    @Test
+    public void whenFailFast_ThenThrowsExceptionInSecondIteration() {
+        assertThatThrownBy(() -> {
+            failFast2();
+        }).isInstanceOf(ConcurrentModificationException.class);
+    }
+
+    @Test
+    public void whenFailSafe_ThenDoesNotThrowException() {
+        assertThat(failSafe1()).isGreaterThanOrEqualTo(0);
+    }
+
+}

core-java-8/src/test/java/com/baeldung/java8/comparator/Java8ComparatorUnitTest.java

@@ -6,7 +6,6 @@ import java.util.Comparator;
 import org.junit.Before;
 import org.junit.Test;
 
-import lombok.Data;
 import static org.junit.Assert.assertTrue;
 
 public class Java8ComparatorUnitTest {
@@ -134,8 +133,7 @@ public class Java8ComparatorUnitTest {
 
     @Test
     public void whenThenComparing_thenSortedByAgeName() {
-        Comparator<Employee> employee_Age_Name_Comparator = Comparator.comparing(Employee::getAge)
+        Comparator<Employee> employee_Age_Name_Comparator = Comparator.comparing(Employee::getAge).thenComparing(Employee::getName);
-            .thenComparing(Employee::getName);
 
         Arrays.sort(someMoreEmployees, employee_Age_Name_Comparator);
         // System.out.println(Arrays.toString(someMoreEmployees));
@@ -144,8 +142,7 @@ public class Java8ComparatorUnitTest {
 
     @Test
     public void whenThenComparing_thenSortedByNameAge() {
-        Comparator<Employee> employee_Name_Age_Comparator = Comparator.comparing(Employee::getName)
+        Comparator<Employee> employee_Name_Age_Comparator = Comparator.comparing(Employee::getName).thenComparingInt(Employee::getAge);
-            .thenComparingInt(Employee::getAge);
 
         Arrays.sort(someMoreEmployees, employee_Name_Age_Comparator);
         // System.out.println(Arrays.toString(someMoreEmployees));

core-java-8/src/test/java/com/baeldung/stream/PrimitiveStreamsUnitTest.java

@@ -2,7 +2,6 @@ package com.baeldung.stream;
 
 import org.junit.Test;
 
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Collectors;

core-java-8/src/test/java/com/baeldung/temporaladjusters/CustomTemporalAdjusterTest.java

@@ -1,7 +1,6 @@
 package com.baeldung.temporaladjusters;
 
 import com.baeldung.temporaladjuster.CustomTemporalAdjuster;
-import org.junit.Assert;
 import org.junit.Test;
 
 import java.time.LocalDate;

core-java-9/README.md

@@ -19,3 +19,4 @@
 - [Java 9 java.util.Objects Additions](http://www.baeldung.com/java-9-objects-new)
 - [Compact Strings in Java 9](http://www.baeldung.com/java-9-compact-string)
 - [Convert Date to LocalDate or LocalDateTime and Back](http://www.baeldung.com/java-date-to-localdate-and-localdatetime)
+- [Java 9 Variable Handles Demistyfied](http://www.baeldung.com/java-variable-handles)

core-java-9/pom.xml

@@ -90,7 +90,7 @@
         <org.slf4j.version>1.7.21</org.slf4j.version>
         <ch.qos.logback.version>1.2.1</ch.qos.logback.version>
         <!-- maven plugins -->
-        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+        <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
         <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
 
         <!-- testing -->

core-java-9/src/test/java/com/baeldung/java9/varhandles/VariableHandlesTest.java

@@ -0,0 +1,106 @@
+package com.baeldung.java9.varhandles;
+
+import org.junit.Test;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.VarHandle;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class VariableHandlesTest {
+
+    public int publicTestVariable = 1;
+    private int privateTestVariable = 1;
+    public int variableToSet = 1;
+    public int variableToCompareAndSet = 1;
+    public int variableToGetAndAdd = 0;
+    public byte variableToBitwiseOr = 0;
+
+    @Test
+    public void whenVariableHandleForPublicVariableIsCreated_ThenItIsInitializedProperly() throws NoSuchFieldException, IllegalAccessException {
+        VarHandle publicIntHandle = MethodHandles
+          .lookup()
+          .in(VariableHandlesTest.class)
+          .findVarHandle(VariableHandlesTest.class, "publicTestVariable", int.class);
+
+        assertThat(publicIntHandle.coordinateTypes().size() == 1);
+        assertThat(publicIntHandle.coordinateTypes().get(0) == VariableHandles.class);
+
+    }
+
+    @Test
+    public void whenVariableHandleForPrivateVariableIsCreated_ThenItIsInitializedProperly() throws NoSuchFieldException, IllegalAccessException {
+        VarHandle privateIntHandle = MethodHandles
+          .privateLookupIn(VariableHandlesTest.class, MethodHandles.lookup())
+          .findVarHandle(VariableHandlesTest.class, "privateTestVariable", int.class);
+
+        assertThat(privateIntHandle.coordinateTypes().size() == 1);
+        assertThat(privateIntHandle.coordinateTypes().get(0) == VariableHandlesTest.class);
+
+    }
+
+    @Test
+    public void whenVariableHandleForArrayVariableIsCreated_ThenItIsInitializedProperly() throws NoSuchFieldException, IllegalAccessException {
+        VarHandle arrayVarHandle = MethodHandles
+          .arrayElementVarHandle(int[].class);
+
+        assertThat(arrayVarHandle.coordinateTypes().size() == 2);
+        assertThat(arrayVarHandle.coordinateTypes().get(0) == int[].class);
+    }
+
+    @Test
+    public void givenVarHandle_whenGetIsInvoked_ThenValueOfVariableIsReturned() throws NoSuchFieldException, IllegalAccessException {
+        VarHandle publicIntHandle = MethodHandles
+          .lookup()
+          .in(VariableHandlesTest.class)
+          .findVarHandle(VariableHandlesTest.class, "publicTestVariable", int.class);
+
+        assertThat((int) publicIntHandle.get(this) == 1);
+    }
+
+    @Test
+    public void givenVarHandle_whenSetIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
+        VarHandle publicIntHandle = MethodHandles
+          .lookup()
+          .in(VariableHandlesTest.class)
+          .findVarHandle(VariableHandlesTest.class, "variableToSet", int.class);
+        publicIntHandle.set(this, 15);
+
+        assertThat((int) publicIntHandle.get(this) == 15);
+    }
+
+    @Test
+    public void givenVarHandle_whenCompareAndSetIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
+        VarHandle publicIntHandle = MethodHandles
+          .lookup()
+          .in(VariableHandlesTest.class)
+          .findVarHandle(VariableHandlesTest.class, "variableToCompareAndSet", int.class);
+        publicIntHandle.compareAndSet(this, 1, 100);
+
+        assertThat((int) publicIntHandle.get(this) == 100);
+    }
+
+    @Test
+    public void givenVarHandle_whenGetAndAddIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
+        VarHandle publicIntHandle = MethodHandles
+          .lookup()
+          .in(VariableHandlesTest.class)
+          .findVarHandle(VariableHandlesTest.class, "variableToGetAndAdd", int.class);
+        int before = (int) publicIntHandle.getAndAdd(this, 200);
+
+        assertThat(before == 0);
+        assertThat((int) publicIntHandle.get(this) == 200);
+    }
+
+    @Test
+    public void givenVarHandle_whenGetAndBitwiseOrIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
+        VarHandle publicIntHandle = MethodHandles
+          .lookup()
+          .in(VariableHandlesTest.class)
+          .findVarHandle(VariableHandlesTest.class, "variableToBitwiseOr", byte.class);
+        byte before = (byte) publicIntHandle.getAndBitwiseOr(this, (byte) 127);
+
+        assertThat(before == 0);
+        assertThat(variableToBitwiseOr == 127);
+    }
+}

core-java-sun/pom.xml

@@ -483,7 +483,7 @@
         <avaitility.version>1.7.0</avaitility.version>
 
         <!-- maven plugins -->
-        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+        <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
         <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
     </properties>
 </project>

core-java/README.md

@@ -126,3 +126,9 @@
 - [Java – Append Data to a File](http://www.baeldung.com/java-append-to-file)
 - [Introduction to the Java ArrayDeque](http://www.baeldung.com/java-array-deque)
 - [Guide to java.util.Formatter](http://www.baeldung.com/java-string-formatter)
+- [Batch Processing in JDBC](http://www.baeldung.com/jdbc-batch-processing)
+- [Check if a Java Array Contains a Value](http://www.baeldung.com/java-array-contains-value)
+- [How to Invert an Array in Java](http://www.baeldung.com/java-invert-array)
+- [Guide to the Cipher Class](http://www.baeldung.com/java-cipher-class)
+- [A Guide to Java Initialization](http://www.baeldung.com/java-initialization)
+

core-java/pom.xml

@@ -180,12 +180,7 @@
             <artifactId>esapi</artifactId>
             <version>2.1.0.1</version>
         </dependency>
-		<dependency>
+
-			<groupId>com.h2database</groupId>
-			<artifactId>h2</artifactId>
-			<version>1.4.196</version>
-			<scope>runtime</scope>
-		</dependency>		
         <dependency>
             <groupId>com.sun.messaging.mq</groupId>
             <artifactId>fscontext</artifactId>
@@ -221,13 +216,17 @@
 		    <artifactId>spring-web</artifactId>
 		    <version>4.3.4.RELEASE</version>
 		</dependency>
-
  		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter</artifactId>
 			<version>1.5.8.RELEASE</version>
 		</dependency>
-
+        <dependency>
+            <groupId>org.hsqldb</groupId>
+            <artifactId>hsqldb</artifactId>
+            <version>2.4.0</version>
+            <scope>runtime</scope>
+        </dependency>
     </dependencies>
 
     <build>
@@ -261,7 +260,7 @@
                         <exclude>**/*LongRunningUnitTest.java</exclude>
                         <exclude>**/*ManualTest.java</exclude>
                     </excludes>
-
+                    <testFailureIgnore>true</testFailureIgnore>
                 </configuration>
             </plugin>
 
@@ -490,7 +489,7 @@
         <avaitility.version>1.7.0</avaitility.version>
 
         <!-- maven plugins -->
-		<maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+        <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
         <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
     </properties>
 </project>

core-java/src/main/java/com/baeldung/array/ArrayInverter.java

@@ -25,7 +25,9 @@ public class ArrayInverter {
     }
 
     public Object[] invertUsingStreams(final Object[] array) {
-        return IntStream.range(1, array.length + 1).mapToObj(i -> array[array.length - i]).toArray();
+        return IntStream.rangeClosed(1, array.length)
+            .mapToObj(i -> array[array.length - i])
+            .toArray();
     }
 
     public void invertUsingCommonsLang(Object[] array) {

core-java/src/main/java/com/baeldung/cipher/Encryptor.java

@@ -0,0 +1,35 @@
+package com.baeldung.cipher;
+
+import javax.crypto.*;
+import javax.crypto.spec.SecretKeySpec;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.security.cert.Certificate;
+
+public class Encryptor {
+
+    public byte[] encryptMessage(byte[] message, byte[] keyBytes) throws InvalidKeyException, NoSuchPaddingException, NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
+        SecretKey secretKey = new SecretKeySpec(keyBytes, "AES");
+        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
+        byte[] encryptedMessage = cipher.doFinal(message);
+        return encryptedMessage;
+    }
+
+    public byte[] encryptMessage(byte[] message, Certificate publicKeyCertificate) throws InvalidKeyException, NoSuchPaddingException, NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
+        cipher.init(Cipher.ENCRYPT_MODE, publicKeyCertificate);
+        byte[] encryptedMessage = cipher.doFinal(message);
+        return encryptedMessage;
+    }
+
+    public byte[] decryptMessage(byte[] encryptedMessage, byte[] keyBytes) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
+        SecretKey secretKey = new SecretKeySpec(keyBytes, "AES");
+        cipher.init(Cipher.DECRYPT_MODE, secretKey);
+        byte[] clearMessage = cipher.doFinal(encryptedMessage);
+        return clearMessage;
+    }
+
+
+}

core-java/src/main/java/com/baeldung/initializationguide/User.java

@@ -0,0 +1,53 @@
+package com.baeldung.initializationguide;
+
+import java.io.Serializable;
+
+public class User implements Serializable, Cloneable {
+    private static final long serialVersionUID = 1L;
+    static String forum;
+    private String name;
+    private int id;
+
+    {
+        id = 0;
+        System.out.println("Instance Initializer");
+    }
+
+    static {
+    	forum = "Java";
+        System.out.println("Static Initializer");
+    }
+
+    public User(String name, int id) {
+        super();
+        this.name = name;
+        this.id = id;
+    }
+
+    public User() {
+        System.out.println("Constructor");
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    @Override
+    protected Object clone() throws CloneNotSupportedException {
+        return this;
+    }
+
+}
+

core-java/src/main/java/com/baeldung/jdbc/BatchProcessing.java

@@ -0,0 +1,96 @@
+package com.baeldung.jdbc;
+
+import java.sql.*;
+import java.util.UUID;
+
+public class BatchProcessing {
+
+    private final String[] EMPLOYEES = new String[]{"Zuck","Mike","Larry","Musk","Steve"};
+    private final String[] DESIGNATIONS = new String[]{"CFO","CSO","CTO","CEO","CMO"};
+    private final String[] ADDRESSES = new String[]{"China","York","Diego","Carolina","India"};
+
+    private Connection connection;
+
+    public void getConnection(){
+        try {
+            Class.forName("org.hsqldb.jdbcDriver");
+            connection = DriverManager.getConnection("jdbc:hsqldb:file:C:\\EMPLOYEEDB", "SA", "");
+            connection.setAutoCommit(false);
+        } catch (Exception e) {
+            e.printStackTrace(System.out);
+        }
+    }
+
+    public void createTables(){
+        try {
+            connection.createStatement().executeUpdate("create table EMPLOYEE (ID VARCHAR(36), NAME VARCHAR(45), DESIGNATION VARCHAR(15))");
+            connection.createStatement().executeUpdate("create table EMP_ADDRESS (ID VARCHAR(36), EMP_ID VARCHAR(36), ADDRESS VARCHAR(45))");
+            System.out.println("Tables Created!!!");
+        } catch (SQLException e) {
+            e.printStackTrace(System.out);
+        }
+    }
+
+    public void useStatement(){
+        try {
+            String insertEmployeeSQL = "INSERT INTO EMPLOYEE(ID, NAME, DESIGNATION) VALUES ('%s','%s','%s');";
+            String insertEmployeeAddrSQL = "INSERT INTO EMP_ADDRESS(ID, EMP_ID, ADDRESS) VALUES ('%s','%s','%s');";
+            Statement statement = connection.createStatement();
+            for(int i = 0; i < EMPLOYEES.length; i++){
+                String employeeId = UUID.randomUUID().toString();
+                statement.addBatch(String.format(insertEmployeeSQL, employeeId, EMPLOYEES[i],DESIGNATIONS[i]));
+                statement.addBatch(String.format(insertEmployeeAddrSQL, UUID.randomUUID().toString(),employeeId,ADDRESSES[i]));
+            }
+            statement.executeBatch();
+            connection.commit();
+        } catch (Exception e) {
+            try {
+                connection.rollback();
+            } catch (SQLException ex) {
+                System.out.println("Error during rollback");
+                System.out.println(ex.getMessage());
+            }
+            e.printStackTrace(System.out);
+        }
+    }
+
+    public void usePreparedStatement(){
+        try {
+            String insertEmployeeSQL = "INSERT INTO EMPLOYEE(ID, NAME, DESIGNATION) VALUES (?,?,?);";
+            String insertEmployeeAddrSQL = "INSERT INTO EMP_ADDRESS(ID, EMP_ID, ADDRESS) VALUES (?,?,?);";
+            PreparedStatement employeeStmt = connection.prepareStatement(insertEmployeeSQL);
+            PreparedStatement empAddressStmt = connection.prepareStatement(insertEmployeeAddrSQL);
+            for(int i = 0; i < EMPLOYEES.length; i++){
+                String employeeId = UUID.randomUUID().toString();
+                employeeStmt.setString(1,employeeId);
+                employeeStmt.setString(2,EMPLOYEES[i]);
+                employeeStmt.setString(3,DESIGNATIONS[i]);
+                employeeStmt.addBatch();
+
+                empAddressStmt.setString(1,UUID.randomUUID().toString());
+                empAddressStmt.setString(2,employeeId);
+                empAddressStmt.setString(3,ADDRESSES[i]);
+                empAddressStmt.addBatch();
+            }
+            employeeStmt.executeBatch();
+            empAddressStmt.executeBatch();
+            connection.commit();
+        } catch (Exception e) {
+            try {
+                connection.rollback();
+            } catch (SQLException ex) {
+                System.out.println("Error during rollback");
+                System.out.println(ex.getMessage());
+            }
+            e.printStackTrace(System.out);
+        }
+    }
+
+    public static void main(String[] args) {
+        BatchProcessing batchProcessing = new BatchProcessing();
+        batchProcessing.getConnection();
+        batchProcessing.createTables();
+        batchProcessing.useStatement();
+        batchProcessing.usePreparedStatement();
+    }
+}

core-java/src/main/java/com/baeldung/tree/BinaryTree.java

@@ -8,15 +8,7 @@ public class BinaryTree {
     Node root;
 
     public void add(int value) {
-
+        root = addRecursive(root, value);
-        Node newNode = new Node(value);
-
-        if (root == null) {
-            root = newNode;
-            return;
-        }
-
-        addRecursive(root, value);
     }
 
     private Node addRecursive(Node current, int value) {
@@ -27,34 +19,41 @@ public class BinaryTree {
 
         if (value < current.value) {
             current.left = addRecursive(current.left, value);
-        } else {
+        } else if (value > current.value) {
             current.right = addRecursive(current.right, value);
         }
 
         return current;
-
     }
 
     public boolean isEmpty() {
         return root == null;
     }
 
+    public int getSize() {
+        return getSizeRecursive(root);
+    }
+
+    private int getSizeRecursive(Node current) {
+        return current == null ? 0 : getSizeRecursive(current.left) + 1 + getSizeRecursive(current.right);
+    }
+
     public boolean containsNode(int value) {
         return containsNodeRecursive(root, value);
     }
 
     private boolean containsNodeRecursive(Node current, int value) {
-
         if (current == null) {
             return false;
-        } else if (value == current.value) {
-            return true;
-        } else if (value < current.value) {
-            return containsNodeRecursive(current.left, value);
-        } else {
-            return containsNodeRecursive(current.right, value);
         }
 
+        if (value == current.value) {
+            return true;
+        }
+
+        return value < current.value
+          ? containsNodeRecursive(current.left, value)
+          : containsNodeRecursive(current.right, value);
     }
 
     public void delete(int value) {
@@ -86,23 +85,18 @@ public class BinaryTree {
             current.value = smallestValue;
             current.right = deleteRecursive(current.right, smallestValue);
             return current;
-
+        }
-        } else if (value < current.value) {
+        if (value < current.value) {
             current.left = deleteRecursive(current.left, value);
             return current;
-        } else {
+        }
+
         current.right = deleteRecursive(current.right, value);
         return current;
     }
-    }
 
     private int findSmallestValue(Node root) {
-
+        return root.left == null ? root.value : findSmallestValue(root.left);
-        if (root.left == null) {
-            return root.value;
-        }
-
-        return findSmallestValue(root.left);
     }
 
     public void traverseInOrder(Node node) {
@@ -125,12 +119,15 @@ public class BinaryTree {
         if (node != null) {
             traversePostOrder(node.left);
             traversePostOrder(node.right);
-
             System.out.print(" " + node.value);
         }
     }
 
     public void traverseLevelOrder() {
+        if (root == null) {
+            return;
+        }
+
         Queue<Node> nodes = new LinkedList<>();
         nodes.add(root);
 

core-java/src/test/java/com/baeldung/cipher/EncryptorUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.cipher;
+
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.security.cert.CertificateFactory;
+import java.security.cert.X509Certificate;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class EncryptorUnitTest {
+    private String encKeyString;
+    private String message;
+    private String  certificateString;
+    private Encryptor encryptor;
+
+    @Before
+    public void init(){
+        encKeyString =  "1234567890123456";
+        message = "This is a secret message";
+        encryptor =  new Encryptor();
+        certificateString = "-----BEGIN CERTIFICATE-----\n" +
+                "MIICVjCCAb8CAg37MA0GCSqGSIb3DQEBBQUAMIGbMQswCQYDVQQGEwJKUDEOMAwG\n" +
+                "A1UECBMFVG9reW8xEDAOBgNVBAcTB0NodW8ta3UxETAPBgNVBAoTCEZyYW5rNERE\n" +
+                "MRgwFgYDVQQLEw9XZWJDZXJ0IFN1cHBvcnQxGDAWBgNVBAMTD0ZyYW5rNEREIFdl\n" +
+                "YiBDQTEjMCEGCSqGSIb3DQEJARYUc3VwcG9ydEBmcmFuazRkZC5jb20wHhcNMTIw\n" +
+                "ODIyMDUyNzIzWhcNMTcwODIxMDUyNzIzWjBKMQswCQYDVQQGEwJKUDEOMAwGA1UE\n" +
+                "CAwFVG9reW8xETAPBgNVBAoMCEZyYW5rNEREMRgwFgYDVQQDDA93d3cuZXhhbXBs\n" +
+                "ZS5jb20wgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMYBBrx5PlP0WNI/ZdzD\n" +
+                "+6Pktmurn+F2kQYbtc7XQh8/LTBvCo+P6iZoLEmUA9e7EXLRxgU1CVqeAi7QcAn9\n" +
+                "MwBlc8ksFJHB0rtf9pmf8Oza9E0Bynlq/4/Kb1x+d+AyhL7oK9tQwB24uHOueHi1\n" +
+                "C/iVv8CSWKiYe6hzN1txYe8rAgMBAAEwDQYJKoZIhvcNAQEFBQADgYEAASPdjigJ\n" +
+                "kXCqKWpnZ/Oc75EUcMi6HztaW8abUMlYXPIgkV2F7YanHOB7K4f7OOLjiz8DTPFf\n" +
+                "jC9UeuErhaA/zzWi8ewMTFZW/WshOrm3fNvcMrMLKtH534JKvcdMg6qIdjTFINIr\n" +
+                "evnAhf0cwULaebn+lMs8Pdl7y37+sfluVok=\n" +
+                "-----END CERTIFICATE-----";
+    }
+
+    @Test
+    public void givenEncryptionKey_whenMessageIsPassedToEncryptor_thenMessageIsEncrypted() throws Exception {
+        byte[] encryptedMessage = encryptor.encryptMessage(message.getBytes(),encKeyString.getBytes());
+
+        assertThat(encryptedMessage).isNotNull();
+        assertThat(encryptedMessage.length  % 32).isEqualTo(0);
+    }
+
+    @Test
+    public void givenCertificateWithPublicKey_whenMessageIsPassedToEncryptor_thenMessageIsEncrypted() throws Exception {
+        CertificateFactory factory = CertificateFactory.getInstance("X.509");
+        InputStream is = new ByteArrayInputStream(certificateString.getBytes());
+        X509Certificate certificate = (X509Certificate) factory.generateCertificate(is);
+
+        byte[] encryptedMessage = encryptor.encryptMessage(message.getBytes(),certificate);
+
+        assertThat(encryptedMessage).isNotNull();
+        assertThat(encryptedMessage.length  % 128).isEqualTo(0);
+    }
+
+    @Test
+    public void givenEncryptionKey_whenMessageIsEncrypted_thenDecryptMessage() throws Exception{
+        byte[] encryptedMessageBytes = encryptor.encryptMessage(message.getBytes(),encKeyString.getBytes());
+
+        byte[] clearMessageBytes = encryptor.decryptMessage(encryptedMessageBytes, encKeyString.getBytes());
+
+        assertThat(message).isEqualTo(new String(clearMessageBytes));
+    }
+}

core-java/src/test/java/com/baeldung/collection/WhenComparingTreeMapVsHashMap.java

@@ -0,0 +1,60 @@
+package com.baeldung.collection;
+
+import java.util.ConcurrentModificationException;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.TreeMap;
+
+import org.hamcrest.Matchers;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class WhenComparingTreeMapVsHashMap {
+
+    @Test
+    public void whenInsertObjectsTreeMap_thenNaturalOrder() {
+        Map<Integer, String> treemap = new TreeMap<>();
+        treemap.put(3, "TreeMap");
+        treemap.put(2, "vs");
+        treemap.put(1, "HashMap");
+        Assert.assertThat(treemap.keySet(), Matchers.contains(1, 2, 3));
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void whenInsertNullInTreeMap_thenException() {
+        Map<Integer, String> treemap = new TreeMap<>();
+        treemap.put(null, "NullPointerException");
+    }
+
+    @Test
+    public void whenInsertObjectsHashMap_thenRandomOrder() {
+        Map<Integer, String> hashmap = new HashMap<>();
+        hashmap.put(3, "TreeMap");
+        hashmap.put(2, "vs");
+        hashmap.put(1, "HashMap");
+        Assert.assertThat(hashmap.keySet(), Matchers.containsInAnyOrder(1, 2, 3));
+    }
+
+    @Test
+    public void whenInsertNullInHashMap_thenInsertsNull() {
+        Map<Integer, String> hashmap = new HashMap<>();
+        hashmap.put(null, null);
+        Assert.assertNull(hashmap.get(null));
+    }
+
+    @Test
+    public void givenHashMapAndTreeMap_whenputDuplicates_thenOnlyUnique() {
+        Map<Integer, String> treeMap = new HashMap<>();
+        treeMap.put(1, "Baeldung");
+        treeMap.put(1, "Baeldung");
+
+        Assert.assertTrue(treeMap.size() == 1);
+
+        Map<Integer, String> treeMap2 = new TreeMap<>();
+        treeMap2.put(1, "Baeldung");
+        treeMap2.put(1, "Baeldung");
+
+        Assert.assertTrue(treeMap2.size() == 1);
+    }
+}

core-java/src/test/java/com/baeldung/collection/WhenUsingTreeSet.java

@@ -26,7 +26,6 @@ public class WhenUsingTreeSet {
 
         @Override
         public String toString() {
-            // TODO Auto-generated method stub
             return id.toString();
         }
     }
@@ -189,8 +188,14 @@ public class WhenUsingTreeSet {
         treeSet.add(5);
         treeSet.add(6);
 
+        Set<Integer> expectedSet = new TreeSet<>();
+        expectedSet.add(2);
+        expectedSet.add(3);
+        expectedSet.add(4);
+        expectedSet.add(5);
+
         Set<Integer> subSet = treeSet.subSet(2, 6);
-        System.out.println(subSet);
+        Assert.assertEquals(expectedSet, subSet);
     }
 
     @Test

core-java/src/test/java/com/baeldung/initializationguide/UserTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.initializationguide;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.lang.reflect.InvocationTargetException;
+
+public class UserTest {
+
+    @Test
+    public void givenUserInstance_whenIntializedWithNew_thenInstanceIsNotNull() {
+        User user = new User("Alice", 1);
+        assertThat(user).isNotNull();
+    }
+
+    @Test
+    public void givenUserInstance_whenInitializedWithReflection_thenInstanceIsNotNull() throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, NoSuchMethodException, SecurityException {
+        User user = User.class.getConstructor(String.class, int.class)
+            .newInstance("Alice", 2);
+        assertThat(user).isNotNull();
+    }
+
+    @Test
+    public void givenUserInstance_whenCopiedWithClone_thenExactMatchIsCreated() throws CloneNotSupportedException {
+        User user = new User("Alice", 3);
+        User clonedUser = (User) user.clone();
+        assertThat(clonedUser).isEqualTo(user);
+    }
+
+    @Test
+    public void givenUserInstance_whenValuesAreNotInitialized_thenUserNameAndIdReturnDefault() {
+        User user = new User();
+        assertThat(user.getName()).isNull();
+        assertThat(user.getId() == 0);
+    }
+}

core-java/src/test/java/com/baeldung/jdbc/BatchProcessingTest.java

@@ -0,0 +1,71 @@
+package com.baeldung.jdbc;
+
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.MockitoAnnotations;
+import org.mockito.junit.MockitoJUnitRunner;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.Statement;
+
+@RunWith(MockitoJUnitRunner.class)
+public class BatchProcessingTest {
+
+
+    @InjectMocks
+    private BatchProcessing target = new BatchProcessing();
+
+    @Mock
+    private Connection connection;
+
+    @Mock
+    private Statement statement;
+
+    @Mock
+    private PreparedStatement employeeStatement;
+
+    @Mock
+    private PreparedStatement employeeAddressStatement;
+
+    @Before
+    public void before(){
+        MockitoAnnotations.initMocks(this);
+    }
+
+
+    @Test
+    public void when_useStatement_thenInsertData_success() throws Exception {
+        Mockito.when(connection.createStatement()).thenReturn(statement);
+        target.useStatement();
+    }
+
+    @Test
+    public void when_useStatement_ifThrowException_thenCatchException() throws Exception {
+        Mockito.when(connection.createStatement()).thenThrow(new RuntimeException());
+        target.useStatement();
+    }
+
+    @Test
+    public void when_usePreparedStatement_thenInsertData_success() throws Exception {
+        String insertEmployeeSQL = "INSERT INTO EMPLOYEE(ID, NAME, DESIGNATION) VALUES (?,?,?);";
+        String insertEmployeeAddrSQL = "INSERT INTO EMP_ADDRESS(ID, EMP_ID, ADDRESS) VALUES (?,?,?);";
+        Mockito.when(connection.prepareStatement(insertEmployeeSQL)).thenReturn(employeeStatement);
+        Mockito.when(connection.prepareStatement(insertEmployeeAddrSQL)).thenReturn(employeeAddressStatement);
+        target.usePreparedStatement();
+    }
+
+    @Test
+    public void when_usePreparedStatement_ifThrowException_thenCatchException() throws Exception {
+        String insertEmployeeSQL = "INSERT INTO EMPLOYEE(ID, NAME, DESIGNATION) VALUES (?,?,?);";
+        String insertEmployeeAddrSQL = "INSERT INTO EMP_ADDRESS(ID, EMP_ID, ADDRESS) VALUES (?,?,?);";
+        Mockito.when(connection.prepareStatement(insertEmployeeSQL)).thenReturn(employeeStatement);
+        Mockito.when(connection.prepareStatement(insertEmployeeAddrSQL)).thenThrow(new RuntimeException());
+        target.usePreparedStatement();
+    }
+}

core-java/src/test/java/com/baeldung/tree/BinaryTreeTest.java

@@ -1,5 +1,6 @@
 package com.baeldung.tree;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
@@ -26,6 +27,26 @@ public class BinaryTreeTest {
         assertFalse(bt.containsNode(1));
     }
 
+    @Test
+    public void givenABinaryTree_WhenAddingExistingElement_ThenElementIsNotAdded() {
+
+        BinaryTree bt = createBinaryTree();
+
+        int initialSize = bt.getSize();
+
+        assertTrue(bt.containsNode(3));
+        bt.add(3);
+        assertEquals(initialSize, bt.getSize());
+    }
+
+    @Test
+    public void givenABinaryTree_WhenLookingForNonExistingElement_ThenReturnsFalse() {
+
+        BinaryTree bt = createBinaryTree();
+
+        assertFalse(bt.containsNode(99));
+    }
+
     @Test
     public void givenABinaryTree_WhenDeletingElements_ThenTreeDoesNotContainThoseElements() {
 
@@ -36,6 +57,19 @@ public class BinaryTreeTest {
         assertFalse(bt.containsNode(9));
     }
 
+    @Test
+    public void givenABinaryTree_WhenDeletingNonExistingElement_ThenTreeDoesNotDelete() {
+
+        BinaryTree bt = createBinaryTree();
+
+        int initialSize = bt.getSize();
+
+        assertFalse(bt.containsNode(99));
+        bt.delete(99);
+        assertFalse(bt.containsNode(99));
+        assertEquals(initialSize, bt.getSize());
+    }
+
     @Test
     public void givenABinaryTree_WhenTraversingInOrder_ThenPrintValues() {
 

core-kotlin/pom.xml

@@ -105,7 +105,11 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.5.1</version>
+                <version>3.7.0</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>                
                 <executions>
                     <!-- Replacing default-compile as it is treated specially 
                         by maven -->

dubbo/pom.xml

@@ -52,6 +52,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.7.0</version>              
                 <configuration>
                     <source>1.8</source>
                     <target>1.8</target>

eclipse/README.md

@@ -1 +0,0 @@
-## Relevant articles:

ejb/ejb-session-beans/pom.xml

@@ -82,7 +82,7 @@
         <plugins>
             <plugin>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.1</version>
+                <version>3.7.0</version>
                 <configuration>
                     <source>1.8</source>
                     <target>1.8</target>

flyway/pom.xml

@@ -0,0 +1,70 @@
+<?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>flyway</artifactId>
+    <packaging>jar</packaging>
+
+    <name>flyway</name>
+    <description>Flyway Callbacks Demo</description>
+
+    <parent>
+        <artifactId>parent-boot-5</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-boot-5</relativePath>
+    </parent>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+        <java.version>1.8</java.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.flywaydb</groupId>
+            <artifactId>flyway-core</artifactId>
+            <version>5.0.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-jdbc</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <version>6.0.3</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.flywaydb</groupId>
+                <artifactId>flyway-maven-plugin</artifactId>
+                <version>5.0.2</version>
+            </plugin>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+
+</project>

flyway/src/main/java/com/baeldung/flywaycallbacks/ExampleFlywayCallback.java

@@ -0,0 +1,33 @@
+package com.baeldung.flywaycallbacks;
+
+import java.sql.Connection;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.flywaydb.core.api.MigrationInfo;
+import org.flywaydb.core.api.callback.BaseFlywayCallback;
+
+public class ExampleFlywayCallback extends BaseFlywayCallback {
+
+    private Log log = LogFactory.getLog(getClass());
+
+    @Override
+    public void afterEachMigrate(Connection connection, MigrationInfo info) {
+        log.info("> afterEachMigrate");
+    }
+
+    @Override
+    public void afterMigrate(Connection connection) {
+        log.info("> afterMigrate");
+    }
+
+    @Override
+    public void beforeEachMigrate(Connection connection, MigrationInfo info) {
+        log.info("> beforeEachMigrate");
+    }
+
+    @Override
+    public void beforeMigrate(Connection connection) {
+        log.info("> beforeMigrate");
+    }
+}

flyway/src/main/java/com/baeldung/flywaycallbacks/FlywayApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.flywaycallbacks;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class FlywayApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(FlywayApplication.class, args);
+    }
+
+}

flyway/src/main/resources/db/callbacks/beforeEachMigrate.sql

@@ -0,0 +1 @@
+SELECT 1

flyway/src/main/resources/db/callbacks/beforeMigrate.sql

@@ -0,0 +1 @@
+SELECT 1

flyway/src/main/resources/db/migration/V1_0__add_table_one.sql

@@ -0,0 +1,5 @@
+create table table_one (
+  id numeric,
+  name  varchar(50),
+  constraint pk_table_one primary key (id)
+);

flyway/src/main/resources/db/migration/V1_1__add_table_two.sql

@@ -0,0 +1,5 @@
+create table table_two (
+  id numeric,
+  name  varchar(50),
+  constraint pk_table_two primary key (id)
+);

flyway/src/main/resources/logback.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%date [%thread] %-5level %logger{36} - %message%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <logger name="org.springframework" level="WARN" />
+    <logger name="org.springframework.transaction" level="WARN" />
+
+    <!-- in order to debug some marshalling issues, this needs to be TRACE -->
+    <logger name="org.springframework.web.servlet.mvc" level="WARN" />
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

flyway/src/test/java/com/baeldung/flywaycallbacks/FlywayApplicationTest.java

@@ -0,0 +1,68 @@
+package com.baeldung.flywaycallbacks;
+
+import javax.sql.DataSource;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.flywaydb.core.Flyway;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.annotation.DirtiesContext.ClassMode;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringRunner;
+
+@RunWith(SpringRunner.class)
+@DirtiesContext(classMode = ClassMode.AFTER_EACH_TEST_METHOD)
+@ContextConfiguration(classes = FlywayCallbackTestConfig.class)
+public class FlywayApplicationTest {
+
+    private Log log = LogFactory.getLog(getClass());
+
+    @Autowired
+    private DataSource dataSource;
+
+    @Test
+    public void migrateWithNoCallbacks() {
+        logTestBoundary("migrateWithNoCallbacks");
+        Flyway flyway = new Flyway();
+        flyway.setDataSource(dataSource);
+        flyway.setLocations("db/migration");
+        flyway.migrate(); 
+    }
+
+    @Test
+    public void migrateWithJavaCallbacks() {
+        logTestBoundary("migrateWithJavaCallbacks");
+        Flyway flyway = new Flyway();
+        flyway.setDataSource(dataSource);
+        flyway.setLocations("db/migration");
+        flyway.setCallbacks(new ExampleFlywayCallback());
+        flyway.migrate();
+    }
+
+    @Test
+    public void migrateWithSqlCallbacks() {
+        logTestBoundary("migrateWithSqlCallbacks");
+        Flyway flyway = new Flyway();
+        flyway.setDataSource(dataSource);
+        flyway.setLocations("db/migration", "db/callbacks");
+        flyway.migrate(); 
+    }
+
+    @Test
+    public void migrateWithSqlAndJavaCallbacks() {
+        logTestBoundary("migrateWithSqlAndJavaCallbacks");
+        Flyway flyway = new Flyway();
+        flyway.setDataSource(dataSource);
+        flyway.setLocations("db/migration", "db/callbacks");
+        flyway.setCallbacks(new ExampleFlywayCallback());
+        flyway.migrate(); 
+    }
+
+    private void logTestBoundary(String testName) {
+        System.out.println("\n");
+        log.info("> " + testName);
+    }
+ }

flyway/src/test/java/com/baeldung/flywaycallbacks/FlywayCallbackTestConfig.java

@@ -0,0 +1,21 @@
+package com.baeldung.flywaycallbacks;
+
+import javax.sql.DataSource;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder;
+import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType;
+
+@Configuration
+public class FlywayCallbackTestConfig {
+
+    @Bean
+    public DataSource createDatasource() {
+        EmbeddedDatabaseBuilder dbBuilder = new EmbeddedDatabaseBuilder();
+        return dbBuilder.setType(EmbeddedDatabaseType.H2)
+            .setName("DATABASE")
+            .build();
+    }
+
+}

geotools/pom.xml

@@ -59,6 +59,7 @@
                 <inherited>true</inherited>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.7.0</version>               
                 <configuration>
                     <source>1.8</source>
                     <target>1.8</target>

guest/core-java-9/pom.xml

@@ -16,7 +16,7 @@
     <plugins>
       <plugin>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.6.2</version>
+        <version>3.7.0</version>
         <configuration>
           <source>1.9</source>
           <target>1.9</target>

guest/core-java/pom.xml

@@ -22,7 +22,7 @@
 		<plugins>
 			<plugin>
 				<artifactId>maven-compiler-plugin</artifactId>
-				<version>3.5</version>
+				<version>3.7.0</version>
 				<configuration>
 					<source>1.8</source>
 					<target>1.8</target>

guest/junit5-example/pom.xml

@@ -41,7 +41,7 @@
 		<plugins>
 			<plugin>
 				<artifactId>maven-compiler-plugin</artifactId>
-				<version>3.5</version>
+				<version>3.7.0</version>
 				<configuration>
 					<source>1.8</source>
 					<target>1.8</target>

guest/log4j2-example/pom.xml

@@ -39,7 +39,7 @@
 		<plugins>
 			<plugin>
 				<artifactId>maven-compiler-plugin</artifactId>
-				<version>3.5</version>
+				<version>3.7.0</version>
 				<configuration>
 					<source>1.8</source>
 					<target>1.8</target>

guest/logback-example/pom.xml

@@ -30,7 +30,7 @@
 		<plugins>
 			<plugin>
 				<artifactId>maven-compiler-plugin</artifactId>
-				<version>3.5</version>
+				<version>3.7.0</version>
 				<configuration>
 					<source>1.8</source>
 					<target>1.8</target>

guest/memory-leaks/pom.xml

@@ -28,7 +28,7 @@
 		<plugins>
 			<plugin>
 				<artifactId>maven-compiler-plugin</artifactId>
-				<version>3.5</version>
+				<version>3.7.0</version>
 				<configuration>
 					<source>1.8</source>
 					<target>1.8</target>

guest/spring-boot-app/pom.xml

@@ -38,7 +38,7 @@
         <plugins>
             <plugin>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.6.1</version>
+                <version>3.7.0</version>
                 <configuration>
                     <source>1.8</source>
                     <target>1.8</target>

guest/thread-pools/pom.xml

@@ -17,7 +17,7 @@
 		<plugins>
 			<plugin>
 				<artifactId>maven-compiler-plugin</artifactId>
-				<version>3.5.1</version>
+				<version>3.7.0</version>
 				<configuration>
 					<source>1.8</source>
 					<target>1.8</target>

guest/tomcat-app/pom.xml

@@ -52,7 +52,7 @@
         <plugins>
             <plugin>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.5.1</version>
+                <version>3.7.0</version>
                 <configuration>
                     <source>1.8</source>
                     <target>1.8</target>

guest/webservices/rest-client/pom.xml

@@ -8,7 +8,7 @@
     <plugins>
       <plugin>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.5</version>
+        <version>3.7.0</version>
         <configuration>
           <source>1.8</source>
           <target>1.8</target>

guest/webservices/rest-server/pom.xml

@@ -33,7 +33,7 @@
 		<plugins>
 			<plugin>
 				<artifactId>maven-compiler-plugin</artifactId>
-				<version>3.5.1</version>
+				<version>3.7.0</version>
 				<configuration>
 					<source>1.8</source>
 					<target>1.8</target>

hibernate5/pom.xml

@@ -16,7 +16,7 @@
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<!-- Maven plugins -->
-        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+        <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
         <hibernate.version>5.2.12.Final</hibernate.version>
         <mysql.version>6.0.6</mysql.version>
         <mariaDB4j.version>2.2.3</mariaDB4j.version>
@@ -41,7 +41,7 @@
         <dependency>
             <groupId>com.h2database</groupId>
             <artifactId>h2</artifactId>
-            <version>1.4.194</version>
+            <version>1.4.196</version>
         </dependency>
         <dependency>
             <groupId>org.hibernate</groupId>

hibernate5/src/main/java/com/baeldung/hibernate/App.java

@@ -1,30 +0,0 @@
-package com.baeldung.hibernate;
-
-import org.hibernate.Session;
-import org.hibernate.SessionFactory;
-import org.hibernate.Transaction;
-
-import com.baeldung.hibernate.pojo.Supplier;
-
-/**
- * Hello world!
- *
- */
-public class App {
-    public static void main(String[] args) {
-        try {
-            // NOTE: this is just for boostrap testing for multitenancy.
-            System.out.println("Checking the system.");
-            SessionFactory sessionFactory = HibernateMultiTenantUtil.getSessionFactory();
-            Session currentSession = sessionFactory.withOptions().tenantIdentifier("h2db1").openSession();
-            Transaction transaction = currentSession.getTransaction();
-            transaction.begin();
-            currentSession.createCriteria(Supplier.class).list().stream().forEach(System.out::println);
-            transaction.commit();
-            
-        } catch (Exception e) {
-            e.printStackTrace();
-        }
-
-    }
-}

hibernate5/src/main/java/com/baeldung/hibernate/ConfigurableMultiTenantConnectionProvider.java

@@ -1,41 +0,0 @@
-package com.baeldung.hibernate;
-
-import java.sql.Connection;
-import java.sql.SQLException;
-import java.util.HashMap;
-import java.util.Map;
-
-import org.hibernate.engine.jdbc.connections.spi.AbstractMultiTenantConnectionProvider;
-import org.hibernate.engine.jdbc.connections.spi.ConnectionProvider;
-
-public class ConfigurableMultiTenantConnectionProvider extends AbstractMultiTenantConnectionProvider {
-
-    private final Map<String, ConnectionProvider> connectionProviderMap = 
-            new HashMap<>();
-
-    
-    public ConfigurableMultiTenantConnectionProvider(
-            Map<String, ConnectionProvider> connectionProviderMap) {
-        this.connectionProviderMap.putAll( connectionProviderMap );
-    }
-    @Override
-    protected ConnectionProvider getAnyConnectionProvider() {
-        System.out.println("Any");
-        return connectionProviderMap.values().iterator().next();
-    }
-
-    @Override
-    protected ConnectionProvider selectConnectionProvider(String tenantIdentifier) {
-        System.out.println("Specific");
-        return connectionProviderMap.get( tenantIdentifier );
-    }
-    
-    @Override
-    public Connection getConnection(String tenantIdentifier) throws SQLException {
-        Connection connection = super.getConnection(tenantIdentifier);
-        // uncomment to see option 2 for SCHEMA strategy.
-        //connection.createStatement().execute("SET SCHEMA '" + tenantIdentifier + "'");
-        return connection;
-    }
-    
-}

hibernate5/src/main/java/com/baeldung/hibernate/HibernateMultiTenantUtil.java

@@ -1,115 +0,0 @@
-package com.baeldung.hibernate;
-
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
-import java.io.IOException;
-import java.net.URL;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Properties;
-
-import org.hibernate.SessionFactory;
-import org.hibernate.boot.Metadata;
-import org.hibernate.boot.MetadataSources;
-import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
-import org.hibernate.cfg.AvailableSettings;
-import org.hibernate.cfg.Configuration;
-import org.hibernate.cfg.Environment;
-import org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl;
-import org.hibernate.engine.jdbc.connections.spi.ConnectionProvider;
-import org.hibernate.service.ServiceRegistry;
-
-import com.baeldung.hibernate.pojo.Supplier;
-
-public class HibernateMultiTenantUtil {
-    private static SessionFactory sessionFactory;
-    private static Map<String, ConnectionProvider> connectionProviderMap = new HashMap<>();
-    private static final String[] tenantDBNames = { "mydb1", "mydb2" };
-
-    public static SessionFactory getSessionFactory() throws UnsupportedTenancyException, IOException {
-        if (sessionFactory == null) {
-            // Configuration configuration = new Configuration().configure();
-            ServiceRegistry serviceRegistry = configureServiceRegistry();
-            sessionFactory = makeSessionFactory(serviceRegistry);
-
-        }
-        return sessionFactory;
-    }
-
-    private static SessionFactory makeSessionFactory(ServiceRegistry serviceRegistry) {
-        MetadataSources metadataSources = new MetadataSources(serviceRegistry);
-        for (Class annotatedClasses : getAnnotatedClasses()) {
-            metadataSources.addAnnotatedClass(annotatedClasses);
-        }
-
-        Metadata metadata = metadataSources.buildMetadata();
-        return metadata.getSessionFactoryBuilder()
-            .build();
-
-    }
-
-    private static Class<?>[] getAnnotatedClasses() {
-        return new Class<?>[] { Supplier.class };
-    }
-
-    private static ServiceRegistry configureServiceRegistry() throws UnsupportedTenancyException, IOException {
-
-        // Properties properties = configuration.getProperties();
-        Properties properties = getProperties();
-
-        connectionProviderMap = setUpConnectionProviders(properties, tenantDBNames);
-        properties.put(AvailableSettings.MULTI_TENANT_CONNECTION_PROVIDER, new ConfigurableMultiTenantConnectionProvider(connectionProviderMap));
-
-        return new StandardServiceRegistryBuilder().applySettings(properties)
-            .build();
-    }
-
-    private static Properties getProperties() throws IOException {
-        Properties properties = new Properties();
-        URL propertiesURL = Thread.currentThread()
-            .getContextClassLoader()
-            .getResource("hibernate-multitenancy.properties");
-        FileInputStream inputStream = new FileInputStream(propertiesURL.getFile());
-        properties.load(inputStream);
-        System.out.println("LOADED PROPERTIES FROM hibernate.properties");
-
-        return properties;
-    }
-
-    private static Map<String, ConnectionProvider> setUpConnectionProviders(Properties properties, String[] tenantNames) throws UnsupportedTenancyException {
-        Map<String, ConnectionProvider> providerMap = new HashMap<>();
-        for (String tenant : tenantNames) {
-            DriverManagerConnectionProviderImpl connectionProvider = new DriverManagerConnectionProviderImpl();
-
-            String tenantStrategy = properties.getProperty("hibernate.multiTenancy");
-            System.out.println("Strategy:" + tenantStrategy);
-            properties.put(Environment.URL, tenantUrl(properties.getProperty(Environment.URL), tenant, tenantStrategy));
-            System.out.println("URL:" + properties.getProperty(Environment.URL));
-            connectionProvider.configure(properties);
-            System.out.println("Tenant:" + tenant);
-            providerMap.put(tenant, connectionProvider);
-
-        }
-        System.out.println("Added connections for:");
-        providerMap.keySet()
-            .stream()
-            .forEach(System.out::println);
-        return providerMap;
-    }
-
-    private static Object tenantUrl(String originalUrl, String tenant, String tenantStrategy) throws UnsupportedTenancyException {
-        if (tenantStrategy.toUpperCase()
-            .equals("DATABASE")) {
-            return originalUrl.replace(DEFAULT_DB_NAME, tenant);
-        } else if (tenantStrategy.toUpperCase()
-            .equals("SCHEMA")) {
-            return originalUrl + String.format(SCHEMA_TOKEN, tenant);
-        } else {
-            throw new UnsupportedTenancyException("Not yet supported");
-        }
-    }
-
-    public static final String SCHEMA_TOKEN = ";INIT=CREATE SCHEMA IF NOT EXISTS %1$s\\;SET SCHEMA %1$s";
-    public static final String DEFAULT_DB_NAME = "mydb1";
-
-}

hibernate5/src/main/java/com/baeldung/hibernate/dao/GenericDao.java

@@ -1,12 +0,0 @@
-package com.baeldung.hibernate.dao;
-
-import java.util.List;
-
-public interface GenericDao<T> {
-    
-    void save (T entity);
-    void delete (T Entity);
-    T findByName(String name);
-    List<T> findAll();
-    void populate();
-}

hibernate5/src/main/java/com/baeldung/hibernate/dao/SupplierDao.java

@@ -1,80 +0,0 @@
-package com.baeldung.hibernate.dao;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import org.hibernate.Criteria;
-import org.hibernate.Session;
-import org.hibernate.SessionFactory;
-import org.hibernate.Transaction;
-import org.hibernate.criterion.Expression;
-
-import com.baeldung.hibernate.pojo.Supplier;
-
-public class SupplierDao implements GenericDao<Supplier>{
-    private SessionFactory sessionFactory;
-    private String tenant;
-    
-    public SupplierDao(SessionFactory sessionFactory, String tenant) {
-        this.sessionFactory = sessionFactory;
-        this.tenant = tenant;
-        populate();
-    }
-
-    @Override
-    public void save(Supplier entity) {
-        Session session = sessionFactory.withOptions().tenantIdentifier(tenant).openSession();
-        session.save(entity);
-    }
-
-    @Override
-    public void delete(Supplier supplier) {
-        Session session = sessionFactory.withOptions().tenantIdentifier(tenant).openSession();
-        session.delete(supplier);
-    }
-
-    @Override
-    public Supplier findByName(String name) {
-        Session session = sessionFactory.withOptions().tenantIdentifier(tenant).openSession();
-        List<Supplier> fetchedSuppliers = session.createCriteria(Supplier.class).add(Expression.eq("name", name)).list();
-        if (fetchedSuppliers.size()>0) {
-            return fetchedSuppliers.get(0);
-        }else {
-            return null;
-        }
-    }
-
-    @Override
-    public List<Supplier> findAll() {
-        Session session = sessionFactory.withOptions().tenantIdentifier(tenant).openSession();
-        return session.createCriteria(Supplier.class).list();
-    }
-
-    @Override
-    public void populate() {
-        System.out.println("Init DB1");
-        Session session = sessionFactory.withOptions().tenantIdentifier(tenant).openSession();
-        Transaction transaction = session.getTransaction();
-        
-        transaction.begin();
-        session.createSQLQuery("DROP ALL OBJECTS").executeUpdate();
-        session
-            .createSQLQuery(
-                "create table Supplier (id integer generated by default as identity, country varchar(255), name varchar(255), primary key (id))")
-            .executeUpdate();
-        Supplier genertedSupplier = generateEntityForTenant(tenant);
-        System.out.println("Inserting Supplier"+genertedSupplier);
-        save (genertedSupplier);
-        
-    }
-
-    private Supplier generateEntityForTenant(String forTenant) {
-        if (forTenant.equals("mydb1")) {
-            return new Supplier ("John","USA");
-        }
-        return new Supplier ("Miller","UK");
-    }
-    
-    
-
-}

hibernate5/src/main/java/com/baeldung/hibernate/interceptors/CustomInterceptor.java

@@ -0,0 +1,32 @@
+package com.baeldung.hibernate.interceptors;
+
+import java.io.Serializable;
+import java.util.Date;
+
+import org.hibernate.EmptyInterceptor;
+import org.hibernate.type.Type;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.baeldung.hibernate.interceptors.entity.User;
+
+public class CustomInterceptor extends EmptyInterceptor {
+    private static final Logger logger = LoggerFactory.getLogger(CustomInterceptor.class);
+
+    @Override
+    public boolean onSave(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) {
+        if (entity instanceof User) {
+            logger.info(((User) entity).toString());
+        }
+        return super.onSave(entity, id, state, propertyNames, types);
+    }
+    
+    @Override
+    public boolean onFlushDirty(Object entity, Serializable id, Object[] currentState, Object [] previousState, String[] propertyNames, Type[] types) {
+        if (entity instanceof User) {
+            ((User) entity).setLastModified(new Date());
+            logger.info(((User) entity).toString());
+        }
+        return super.onFlushDirty(entity, id, currentState, previousState, propertyNames, types);
+    }
+}

hibernate5/src/main/java/com/baeldung/hibernate/interceptors/CustomInterceptorImpl.java

@@ -0,0 +1,122 @@
+package com.baeldung.hibernate.interceptors;
+
+import java.io.Serializable;
+import java.util.Iterator;
+
+import org.hibernate.CallbackException;
+import org.hibernate.EntityMode;
+import org.hibernate.Interceptor;
+import org.hibernate.Transaction;
+import org.hibernate.type.Type;
+
+public class CustomInterceptorImpl implements Interceptor {
+
+    @Override
+    public boolean onLoad(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) throws CallbackException {
+        // TODO Auto-generated method stub
+        return false;
+    }
+
+    @Override
+    public boolean onFlushDirty(Object entity, Serializable id, Object[] currentState, Object[] previousState, String[] propertyNames, Type[] types) throws CallbackException {
+        // TODO Auto-generated method stub
+        return false;
+    }
+
+    @Override
+    public boolean onSave(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) throws CallbackException {
+        // TODO Auto-generated method stub
+        return false;
+    }
+
+    @Override
+    public void onDelete(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) throws CallbackException {
+        // TODO Auto-generated method stub
+
+    }
+
+    @Override
+    public void onCollectionRecreate(Object collection, Serializable key) throws CallbackException {
+        // TODO Auto-generated method stub
+
+    }
+
+    @Override
+    public void onCollectionRemove(Object collection, Serializable key) throws CallbackException {
+        // TODO Auto-generated method stub
+
+    }
+
+    @Override
+    public void onCollectionUpdate(Object collection, Serializable key) throws CallbackException {
+        // TODO Auto-generated method stub
+
+    }
+
+    @Override
+    public void preFlush(Iterator entities) throws CallbackException {
+        // TODO Auto-generated method stub
+
+    }
+
+    @Override
+    public void postFlush(Iterator entities) throws CallbackException {
+        // TODO Auto-generated method stub
+
+    }
+
+    @Override
+    public Boolean isTransient(Object entity) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public int[] findDirty(Object entity, Serializable id, Object[] currentState, Object[] previousState, String[] propertyNames, Type[] types) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Object instantiate(String entityName, EntityMode entityMode, Serializable id) throws CallbackException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public String getEntityName(Object object) throws CallbackException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Object getEntity(String entityName, Serializable id) throws CallbackException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public void afterTransactionBegin(Transaction tx) {
+        // TODO Auto-generated method stub
+
+    }
+
+    @Override
+    public void beforeTransactionCompletion(Transaction tx) {
+        // TODO Auto-generated method stub
+
+    }
+
+    @Override
+    public void afterTransactionCompletion(Transaction tx) {
+        // TODO Auto-generated method stub
+
+    }
+
+    @Override
+    public String onPrepareStatement(String sql) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+}

hibernate5/src/main/java/com/baeldung/hibernate/interceptors/HibernateUtil.java

@@ -0,0 +1,79 @@
+package com.baeldung.hibernate.interceptors;
+
+import org.apache.commons.lang3.StringUtils;
+import org.hibernate.Interceptor;
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.boot.Metadata;
+import org.hibernate.boot.MetadataSources;
+import org.hibernate.boot.SessionFactoryBuilder;
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.service.ServiceRegistry;
+
+import com.baeldung.hibernate.interceptors.entity.User;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.net.URL;
+import java.util.Properties;
+
+public class HibernateUtil {
+    private static SessionFactory sessionFactory;
+    private static String PROPERTY_FILE_NAME;
+
+    public static SessionFactory getSessionFactory() throws IOException {
+        return getSessionFactory(null);
+    }
+
+    public static SessionFactory getSessionFactory(String propertyFileName) throws IOException {
+        PROPERTY_FILE_NAME = propertyFileName;
+        if (sessionFactory == null) {
+            ServiceRegistry serviceRegistry = configureServiceRegistry();
+            sessionFactory = getSessionFactoryBuilder(serviceRegistry).build();
+        }
+        return sessionFactory;
+    }
+
+    public static SessionFactory getSessionFactoryWithInterceptor(String propertyFileName, Interceptor interceptor) throws IOException {
+        PROPERTY_FILE_NAME = propertyFileName;
+        if (sessionFactory == null) {
+            ServiceRegistry serviceRegistry = configureServiceRegistry();
+            sessionFactory = getSessionFactoryBuilder(serviceRegistry).applyInterceptor(interceptor)
+                .build();
+        }
+        return sessionFactory;
+    }
+
+    public static Session getSessionWithInterceptor(Interceptor interceptor) throws IOException {
+        return getSessionFactory().withOptions()
+            .interceptor(interceptor)
+            .openSession();
+    }
+
+    private static SessionFactoryBuilder getSessionFactoryBuilder(ServiceRegistry serviceRegistry) {
+        MetadataSources metadataSources = new MetadataSources(serviceRegistry);
+        metadataSources.addPackage("com.baeldung.hibernate.interceptors");
+        metadataSources.addAnnotatedClass(User.class);
+
+        Metadata metadata = metadataSources.buildMetadata();
+        return metadata.getSessionFactoryBuilder();
+
+    }
+
+    private static ServiceRegistry configureServiceRegistry() throws IOException {
+        Properties properties = getProperties();
+        return new StandardServiceRegistryBuilder().applySettings(properties)
+            .build();
+    }
+
+    private static Properties getProperties() throws IOException {
+        Properties properties = new Properties();
+        URL propertiesURL = Thread.currentThread()
+            .getContextClassLoader()
+            .getResource(StringUtils.defaultString(PROPERTY_FILE_NAME, "hibernate-interceptors.properties"));
+        try (FileInputStream inputStream = new FileInputStream(propertiesURL.getFile())) {
+            properties.load(inputStream);
+        }
+        return properties;
+    }
+}

hibernate5/src/main/java/com/baeldung/hibernate/interceptors/entity/User.java

@@ -0,0 +1,64 @@
+package com.baeldung.hibernate.interceptors.entity;
+
+import java.util.Date;
+
+import javax.persistence.Basic;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.Temporal;
+import javax.persistence.TemporalType;
+
+@Entity(name = "hbi_user")
+public class User {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.SEQUENCE)
+    private long id;
+    private String name;
+    private String about;
+    @Basic
+    @Temporal(TemporalType.DATE)
+    private Date lastModified;
+
+    public User() {
+    }
+
+    public User(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Date getLastModified() {
+        return lastModified;
+    }
+
+    public void setLastModified(Date lastModified) {
+        this.lastModified = lastModified;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public String getAbout() {
+        return about;
+    }
+
+    public void setAbout(String about) {
+        this.about = about;
+    }
+
+    @Override
+    public String toString() {
+        return String.format("ID: %d\nName: %s\nLast Modified: %s\nAbout: %s\n", getId(), getName(), getLastModified(), getAbout());
+    }
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/Supplier.java

@@ -1,67 +0,0 @@
-package com.baeldung.hibernate.pojo;
-// Generated Feb 9, 2017 11:31:36 AM by Hibernate Tools 5.1.0.Final
-
-import javax.persistence.Entity;
-import javax.persistence.GeneratedValue;
-import javax.persistence.GenerationType;
-import javax.persistence.Id;
-import javax.persistence.Table;
-
-import org.junit.runners.Suite.SuiteClasses;
-
-
-/**
- * Suppliers generated by hbm2java
- */
-@Entity(name = "Supplier")
-@Table(name ="Supplier")
-public class Supplier implements java.io.Serializable {
-
-    @Id
-    @GeneratedValue(strategy = GenerationType.IDENTITY)
-    private Integer id;
-    private String name;
-    private String country;
-
-    public Supplier() {
-    }
-
-    public Supplier(String name, String country) {
-        this.name = name;
-        this.country = country;
-    }
-
-    public Integer getId() {
-        return this.id;
-    }
-
-    public void setId(Integer id) {
-        this.id = id;
-    }
-
-    public String getName() {
-        return this.name;
-    }
-
-    public void setName(String name) {
-        this.name = name;
-    }
-
-    public String getCountry() {
-        return this.country;
-    }
-
-    public void setCountry(String country) {
-        this.country = country;
-    }
-
-    @Override
-    public String toString() {
-        return new StringBuffer().append("[").append(id).append(",").append(name).append(",").append(country).append("]").toString();
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-        return name.equals(((Supplier) obj).getName());
-    }
-}

hibernate5/src/test/java/com/baeldung/hibernate/MultiTenantDaoHibernateIntegrationTest.java

@@ -1,30 +0,0 @@
-package com.baeldung.hibernate;
-
-import java.io.IOException;
-
-import org.hibernate.SessionFactory;
-import org.junit.Test;
-
-import com.baeldung.hibernate.dao.SupplierDao;
-import com.baeldung.hibernate.pojo.Supplier;
-
-import static org.junit.Assert.assertNull;;
-
-public class MultiTenantDaoHibernateIntegrationTest {
-    @Test
-    public void givenDBMode_whenFetchingSuppliersByName_thenChecking() throws UnsupportedTenancyException, IOException {
-        SessionFactory sessionFactory = HibernateMultiTenantUtil.getSessionFactory();
-        
-        SupplierDao myDb1Dao = new SupplierDao(sessionFactory, "mydb1");
-        Supplier db1SupplierName = myDb1Dao.findByName("John");
-        
-        // finding the same supplier name in another tenant
-        // and we should not be able to find in there and both dbs are different.
-        SupplierDao myDb2Dao = new SupplierDao(sessionFactory, "mydb2");
-        Supplier db2SupplierName = myDb2Dao.findByName(db1SupplierName.getName());
-        
-        assertNull(db2SupplierName);
-        
-    }
-
-}

hibernate5/src/test/java/com/baeldung/hibernate/interceptors/HibernateInterceptorTest.java

@@ -0,0 +1,62 @@
+package com.baeldung.hibernate.interceptors;
+
+import java.io.IOException;
+import java.io.Serializable;
+
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.Transaction;
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.baeldung.hibernate.interceptors.entity.User;
+
+public class HibernateInterceptorTest {
+    private static SessionFactory sessionFactory;
+    private static Serializable userId;
+
+    @Before
+    public void init() throws IOException {
+        sessionFactory = HibernateUtil.getSessionFactoryWithInterceptor(null, new CustomInterceptor());
+    }
+    
+    @AfterClass
+    public static void finish() {
+        if(userId != null) {
+            Session session = sessionFactory.getCurrentSession();
+            Transaction transaction = session.beginTransaction();
+            User user = session.load(User.class, userId);
+            if(user != null) {
+                session.delete(user);
+            }
+            transaction.commit();
+            session.close();
+        }
+    }
+    
+    @Test
+    public void givenHibernateInterceptorAndSessionScoped_whenUserCreated_shouldSucceed() {
+        Session session = sessionFactory.withOptions().interceptor(new CustomInterceptor()).openSession();
+        User user = new User("Benjamin Franklin");
+        Transaction transaction = session.beginTransaction();
+        userId = session.save(user);
+        transaction.commit();
+        session.close();
+    }
+    
+    @Test
+    public void givenHibernateInterceptorAndSessionFactoryScoped_whenUserModified_shouldSucceed() {
+        Session session = sessionFactory.openSession();
+        Transaction transaction = session.beginTransaction();
+        User user = session.load(User.class, userId);
+        if(user != null) {
+            user.setAbout("I am a scientist.");
+            session.update(user);
+        }
+        transaction.commit();
+        session.close();
+    }
+    
+}

hibernate5/src/test/java/com/baeldung/hibernate/multitenancy/Car.java

@@ -0,0 +1,26 @@
+package com.baeldung.hibernate.multitenancy;
+
+import java.io.Serializable;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Table;
+
+@Entity(name = "Car")
+@Table(name = "Car")
+public class Car implements Serializable {
+
+    private static final long serialVersionUID = 1015320564683423342L;
+
+    private String brand;
+
+    @Id
+    public String getBrand() {
+        return brand;
+    }
+
+    public void setBrand(String brand) {
+        this.brand = brand;
+    }
+
+}

hibernate5/src/test/java/com/baeldung/hibernate/multitenancy/MultitenancyIntegrationTest.java

@@ -0,0 +1,104 @@
+package com.baeldung.hibernate.multitenancy;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import java.io.IOException;
+import java.util.Properties;
+
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.Transaction;
+import org.hibernate.boot.MetadataSources;
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.cfg.AvailableSettings;
+import org.hibernate.context.spi.CurrentTenantIdentifierResolver;
+import org.hibernate.service.ServiceRegistry;
+import org.junit.Before;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.MockitoAnnotations;
+
+import com.baeldung.hibernate.multitenancy.database.TenantIdNames;
+
+public abstract class MultitenancyIntegrationTest {
+
+    public abstract String getPropertyFile();
+
+    @Mock
+    private CurrentTenantIdentifierResolver currentTenantIdentifierResolver;
+
+    private SessionFactory sessionFactory;
+
+    @Before
+    public void setup() throws IOException {
+        MockitoAnnotations.initMocks(this);
+
+        Mockito.when(currentTenantIdentifierResolver.validateExistingCurrentSessions())
+            .thenReturn(false);
+
+        Properties properties = getHibernateProperties();
+        properties.put(AvailableSettings.MULTI_TENANT_IDENTIFIER_RESOLVER, currentTenantIdentifierResolver);
+
+        sessionFactory = buildSessionFactory(properties);
+
+        initTenant(TenantIdNames.MYDB1);
+        initTenant(TenantIdNames.MYDB2);
+    }
+
+    protected void initTenant(String tenantId) {
+        whenCurrentTenantIs(tenantId);
+        createCarTable();
+    }
+
+    protected void whenCurrentTenantIs(String tenantId) {
+        Mockito.when(currentTenantIdentifierResolver.resolveCurrentTenantIdentifier())
+            .thenReturn(tenantId);
+    }
+
+    protected void whenAddCar(String brand) {
+        Session session = sessionFactory.openSession();
+        Transaction tx = session.beginTransaction();
+        Car car = new Car();
+        car.setBrand(brand);
+        session.save(car);
+        tx.commit();
+    }
+
+    protected void thenCarFound(String brand) {
+        Session session = sessionFactory.openSession();
+        assertNotNull(session.get(Car.class, brand));
+    }
+
+    protected void thenCarNotFound(String brand) {
+        Session session = sessionFactory.openSession();
+        assertNull(session.get(Car.class, brand));
+    }
+
+    @SuppressWarnings("deprecation")
+    private void createCarTable() {
+        Session session = sessionFactory.openSession();
+        Transaction tx = session.beginTransaction();
+        session.createSQLQuery("drop table Car if exists")
+            .executeUpdate();
+        session.createSQLQuery("create table Car (brand varchar(255) primary key)")
+            .executeUpdate();
+        tx.commit();
+    }
+
+    private Properties getHibernateProperties() throws IOException {
+        Properties properties = new Properties();
+        properties.load(getClass().getResourceAsStream(getPropertyFile()));
+        return properties;
+    }
+
+    private static SessionFactory buildSessionFactory(Properties properties) {
+        ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(properties)
+            .build();
+        MetadataSources metadataSources = new MetadataSources(serviceRegistry);
+        metadataSources.addAnnotatedClass(Car.class);
+        return metadataSources.buildMetadata()
+            .buildSessionFactory();
+    }
+
+}

hibernate5/src/test/java/com/baeldung/hibernate/multitenancy/database/DatabaseApproachMultitenancyIntegrationTest.java

@@ -0,0 +1,25 @@
+package com.baeldung.hibernate.multitenancy.database;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+import com.baeldung.hibernate.multitenancy.MultitenancyIntegrationTest;
+
+public class DatabaseApproachMultitenancyIntegrationTest extends MultitenancyIntegrationTest {
+
+    @Override
+    public String getPropertyFile() {
+        return "/hibernate-database-multitenancy.properties";
+    }
+
+    @Test
+    public void givenDatabaseApproach_whenAddingEntries_thenOnlyAddedToConcreteDatabase() throws IOException {
+        whenCurrentTenantIs(TenantIdNames.MYDB1);
+        whenAddCar("myCar");
+        thenCarFound("myCar");
+        whenCurrentTenantIs(TenantIdNames.MYDB2);
+        thenCarNotFound("myCar");
+    }
+
+}

hibernate5/src/test/java/com/baeldung/hibernate/multitenancy/database/MapMultiTenantConnectionProvider.java

@@ -0,0 +1,42 @@
+package com.baeldung.hibernate.multitenancy.database;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Properties;
+
+import org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl;
+import org.hibernate.engine.jdbc.connections.spi.AbstractMultiTenantConnectionProvider;
+import org.hibernate.engine.jdbc.connections.spi.ConnectionProvider;
+
+@SuppressWarnings("serial")
+public class MapMultiTenantConnectionProvider extends AbstractMultiTenantConnectionProvider {
+
+    private final Map<String, ConnectionProvider> connectionProviderMap = new HashMap<>();
+
+    public MapMultiTenantConnectionProvider() throws IOException {
+        initConnectionProviderForTenant(TenantIdNames.MYDB1);
+        initConnectionProviderForTenant(TenantIdNames.MYDB2);
+    }
+
+    @Override
+    protected ConnectionProvider getAnyConnectionProvider() {
+        return connectionProviderMap.values()
+            .iterator()
+            .next();
+    }
+
+    @Override
+    protected ConnectionProvider selectConnectionProvider(String tenantIdentifier) {
+        return connectionProviderMap.get(tenantIdentifier);
+    }
+
+    private void initConnectionProviderForTenant(String tenantId) throws IOException {
+        Properties properties = new Properties();
+        properties.load(getClass().getResourceAsStream(String.format("/hibernate-database-%s.properties", tenantId)));
+        DriverManagerConnectionProviderImpl connectionProvider = new DriverManagerConnectionProviderImpl();
+        connectionProvider.configure(properties);
+        this.connectionProviderMap.put(tenantId, connectionProvider);
+    }
+
+}

hibernate5/src/test/java/com/baeldung/hibernate/multitenancy/database/TenantIdNames.java

@@ -0,0 +1,6 @@
+package com.baeldung.hibernate.multitenancy.database;
+
+public class TenantIdNames {
+    public static final String MYDB1 = "mydb1";
+    public static final String MYDB2 = "mydb2";
+}

hibernate5/src/test/java/com/baeldung/hibernate/multitenancy/schema/SchemaApproachMultitenancyIntegrationTest.java

@@ -0,0 +1,26 @@
+package com.baeldung.hibernate.multitenancy.schema;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+import com.baeldung.hibernate.multitenancy.MultitenancyIntegrationTest;
+import com.baeldung.hibernate.multitenancy.database.TenantIdNames;
+
+public class SchemaApproachMultitenancyIntegrationTest extends MultitenancyIntegrationTest {
+
+    @Override
+    public String getPropertyFile() {
+        return "/hibernate-schema-multitenancy.properties";
+    }
+
+    @Test
+    public void givenSchemaApproach_whenAddingEntries_thenOnlyAddedToConcreteSchema() throws IOException {
+        whenCurrentTenantIs(TenantIdNames.MYDB1);
+        whenAddCar("Ferrari");
+        thenCarFound("Ferrari");
+        whenCurrentTenantIs(TenantIdNames.MYDB2);
+        thenCarNotFound("Ferrari");
+    }
+
+}

hibernate5/src/test/java/com/baeldung/hibernate/multitenancy/schema/SchemaMultiTenantConnectionProvider.java

@@ -0,0 +1,49 @@
+package com.baeldung.hibernate.multitenancy.schema;
+
+import java.io.IOException;
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.Properties;
+
+import org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl;
+import org.hibernate.engine.jdbc.connections.spi.AbstractMultiTenantConnectionProvider;
+import org.hibernate.engine.jdbc.connections.spi.ConnectionProvider;
+import org.junit.Assert;
+
+@SuppressWarnings("serial")
+public class SchemaMultiTenantConnectionProvider extends AbstractMultiTenantConnectionProvider {
+
+    private final ConnectionProvider connectionProvider = initConnectionProvider();
+
+    @Override
+    protected ConnectionProvider getAnyConnectionProvider() {
+        return connectionProvider;
+    }
+
+    @Override
+    protected ConnectionProvider selectConnectionProvider(String tenantIdentifier) {
+        return connectionProvider;
+    }
+
+    @Override
+    public Connection getConnection(String tenantIdentifier) throws SQLException {
+        Connection connection = super.getConnection(tenantIdentifier);
+        connection.createStatement()
+            .execute(String.format("SET SCHEMA %s;", tenantIdentifier));
+        return connection;
+    }
+
+    private ConnectionProvider initConnectionProvider() {
+        Properties properties = new Properties();
+        try {
+            properties.load(getClass().getResourceAsStream("/hibernate-schema-multitenancy.properties"));
+        } catch (IOException e) {
+            Assert.fail("Error loading resource. Cause: " + e.getMessage());
+        }
+
+        DriverManagerConnectionProviderImpl connectionProvider = new DriverManagerConnectionProviderImpl();
+        connectionProvider.configure(properties);
+        return connectionProvider;
+    }
+
+}

hibernate5/src/test/java/com/baeldung/hibernate/multitenancy/schema/TenantIdNames.java

@@ -0,0 +1,6 @@
+package com.baeldung.hibernate.multitenancy.schema;
+
+public class TenantIdNames {
+    public static final String MYDB1 = "mydb1";
+    public static final String MYDB2 = "mydb2";
+}

hibernate5/src/test/resources/hibernate-database-multitenancy.properties

@@ -0,0 +1,2 @@
+hibernate.multiTenancy=DATABASE
+hibernate.multi_tenant_connection_provider=com.baeldung.hibernate.multitenancy.database.MapMultiTenantConnectionProvider

hibernate5/src/test/resources/hibernate-database-mydb1.properties

@@ -0,0 +1,4 @@
+hibernate.connection.driver_class=org.h2.Driver
+hibernate.connection.url=jdbc:h2:mem:mydb1;DB_CLOSE_DELAY=-1
+hibernate.connection.username=sa
+hibernate.dialect=org.hibernate.dialect.H2Dialect

hibernate5/src/test/resources/hibernate-database-mydb2.properties

@@ -0,0 +1,4 @@
+hibernate.connection.driver_class=org.h2.Driver
+hibernate.connection.url=jdbc:h2:mem:mydb2;DB_CLOSE_DELAY=-1
+hibernate.connection.username=sa
+hibernate.dialect=org.hibernate.dialect.H2Dialect

hibernate5/src/test/resources/hibernate-interceptors.properties

@@ -6,4 +6,5 @@ jdbc.password=
 
 hibernate.dialect=org.hibernate.dialect.H2Dialect
 hibernate.show_sql=true
-hibernate.multiTenancy=DATABASE
+hibernate.hbm2ddl.auto=create-drop
+hibernate.current_session_context_class=org.hibernate.context.internal.ThreadLocalSessionContext

hibernate5/src/test/resources/hibernate-schema-multitenancy.properties

@@ -0,0 +1,7 @@
+hibernate.connection.driver_class=org.h2.Driver
+hibernate.connection.url=jdbc:h2:mem:mydb1;DB_CLOSE_DELAY=-1;INIT=CREATE SCHEMA IF NOT EXISTS MYDB1\\;CREATE SCHEMA IF NOT EXISTS MYDB2\\;
+hibernate.connection.username=sa
+hibernate.connection.autocommit=true
+hibernate.dialect=org.hibernate.dialect.H2Dialect
+hibernate.multiTenancy=SCHEMA
+hibernate.multi_tenant_connection_provider=com.baeldung.hibernate.multitenancy.schema.SchemaMultiTenantConnectionProvider

influxdb/README.md

@@ -0,0 +1,17 @@
+## Influx SDK Tutorial Project
+
+### Relevant Article:
+- [Introduction to using InfluxDB with Java](http://www.baeldung.com/using-influxdb-with-java/)
+
+### Overview
+This Maven project contains the Java code for the article linked above.
+
+### Package Organization
+Java classes for the intro tutorial are in the
+org.baeldung.influxdb package.
+
+
+### Running the tests
+The test class expects an InfluxDB server to be available on localhost, at the default port of 8086 and with the default "admin" credentials.
+
+```

influxdb/pom.xml

@@ -0,0 +1,44 @@
+<?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>influxdb</artifactId>
+    <version>0.1-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>influxdb</name>
+    <description>InfluxDB SDK Tutorial</description>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.influxdb</groupId>
+            <artifactId>influxdb-java</artifactId>
+            <version>${influxdb.sdk.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <!-- Check for the most recent available version: https://projectlombok.org/changelog.html -->
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+
+
+
+    </dependencies>
+
+    <properties>
+        <java.version>1.8</java.version>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <influxdb.sdk.version>2.8</influxdb.sdk.version>
+        <lombok.version>1.16.18</lombok.version>
+
+    </properties>
+
+</project>

influxdb/src/main/java/com/baeldung/influxdb/MemoryPoint.java

@@ -0,0 +1,28 @@
+package com.baeldung.influxdb;
+
+import lombok.Data;
+import org.influxdb.annotation.Column;
+import org.influxdb.annotation.Measurement;
+
+import java.time.Instant;
+
+@Data
+@Measurement(name = "memory")
+public class MemoryPoint {
+
+    @Column(name = "time")
+    private Instant time;
+
+    @Column(name = "name")
+    private String name;
+
+    @Column(name = "free")
+    private Long free;
+
+    @Column(name = "used")
+    private Long used;
+
+    @Column(name = "buffer")
+    private Long buffer;
+
+}

influxdb/src/test/java/com/baeldung/influxdb/InfluxDBConnectionLiveTest.java

@@ -0,0 +1,179 @@
+package com.baeldung.influxdb;
+
+import lombok.extern.slf4j.Slf4j;
+import org.influxdb.InfluxDB;
+import org.influxdb.InfluxDBFactory;
+import org.influxdb.InfluxDBIOException;
+import org.influxdb.dto.*;
+import org.influxdb.impl.InfluxDBResultMapper;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+import static junit.framework.TestCase.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+@Slf4j
+public class InfluxDBConnectionLiveTest {
+
+    @Test
+    public void whenCorrectInfoDatabaseConnects() {
+
+        InfluxDB connection = connectDatabase();
+        assertTrue(pingServer(connection));
+    }
+
+    private InfluxDB connectDatabase() {
+
+        // Connect to database assumed on localhost with default credentials.
+        return  InfluxDBFactory.connect("http://127.0.0.1:8086", "admin", "admin");
+
+    }
+
+    private boolean pingServer(InfluxDB influxDB) {
+        try {
+            // Ping and check for version string
+            Pong response = influxDB.ping();
+            if (response.getVersion().equalsIgnoreCase("unknown")) {
+                log.error("Error pinging server.");
+                return false;
+            } else {
+                log.info("Database version: {}", response.getVersion());
+                return true;
+            }
+        } catch (InfluxDBIOException idbo) {
+            log.error("Exception while pinging database: ", idbo);
+            return false;
+        }
+    }
+
+    @Test
+    public void whenDatabaseCreatedDatabaseChecksOk() {
+
+        InfluxDB connection = connectDatabase();
+
+        // Create "baeldung and check for it
+        connection.createDatabase("baeldung");
+        assertTrue(connection.databaseExists("baeldung"));
+
+        // Verify that nonsense databases are not there
+        assertFalse(connection.databaseExists("foobar"));
+
+        // Drop "baeldung" and check again
+        connection.deleteDatabase("baeldung");
+        assertFalse(connection.databaseExists("baeldung"));
+    }
+
+    @Test
+    public void whenPointsWrittenPointsExists() throws Exception {
+
+        InfluxDB connection = connectDatabase();
+
+        String dbName = "baeldung";
+        connection.createDatabase(dbName);
+
+        // Need a retention policy before we can proceed
+        connection.createRetentionPolicy("defaultPolicy", "baeldung", "30d", 1, true);
+
+        // Since we are doing a batch thread, we need to set this as a default
+        connection.setRetentionPolicy("defaultPolicy");
+
+        // Enable batch mode
+        connection.enableBatch(10, 10, TimeUnit.MILLISECONDS);
+
+        for (int i = 0; i < 10; i++) {
+            Point point = Point.measurement("memory")
+                    .time(System.currentTimeMillis(), TimeUnit.MILLISECONDS)
+                    .addField("name", "server1")
+                    .addField("free", 4743656L)
+                    .addField("used", 1015096L)
+                    .addField("buffer", 1010467L)
+                    .build();
+
+            connection.write(dbName, "defaultPolicy", point);
+            Thread.sleep(2);
+
+        }
+
+        // Unfortunately, the sleep inside the loop doesn't always add enough time to insure
+        // that Influx's batch thread flushes all of the writes and this sometimes fails without
+        // another brief pause.
+        Thread.sleep(10);
+
+        List<MemoryPoint> memoryPointList = getPoints(connection, "Select * from memory", "baeldung");
+
+        assertEquals(10, memoryPointList.size());
+
+        // Turn off batch and clean up
+        connection.disableBatch();
+        connection.deleteDatabase("baeldung");
+        connection.close();
+
+    }
+
+    private List<MemoryPoint> getPoints(InfluxDB connection, String query, String databaseName) {
+
+        // Run the query
+        Query queryObject = new Query(query, databaseName);
+        QueryResult queryResult = connection.query(queryObject);
+
+        // Map it
+        InfluxDBResultMapper resultMapper = new InfluxDBResultMapper();
+        return resultMapper.toPOJO(queryResult, MemoryPoint.class);
+    }
+
+
+
+    @Test
+    public void whenBatchWrittenBatchExists() {
+
+        InfluxDB connection = connectDatabase();
+
+        String dbName = "baeldung";
+        connection.createDatabase(dbName);
+
+        // Need a retention policy before we can proceed
+        // Since we are doing batches, we need not set it
+        connection.createRetentionPolicy("defaultPolicy", "baeldung", "30d", 1, true);
+
+
+        BatchPoints batchPoints = BatchPoints
+                .database(dbName)
+                .retentionPolicy("defaultPolicy")
+                .build();
+        Point point1 = Point.measurement("memory")
+                .time(System.currentTimeMillis(), TimeUnit.MILLISECONDS)
+                .addField("free", 4743656L)
+                .addField("used", 1015096L)
+                .addField("buffer", 1010467L)
+                .build();
+        Point point2 = Point.measurement("memory")
+                .time(System.currentTimeMillis() - 100, TimeUnit.MILLISECONDS)
+                .addField("free", 4743696L)
+                .addField("used", 1016096L)
+                .addField("buffer", 1008467L)
+                .build();
+        batchPoints.point(point1);
+        batchPoints.point(point2);
+        connection.write(batchPoints);
+
+        List<MemoryPoint> memoryPointList = getPoints(connection, "Select * from memory", "baeldung");
+
+        assertEquals(2, memoryPointList.size());
+        assertTrue(4743696L == memoryPointList.get(0).getFree());
+
+
+        memoryPointList = getPoints(connection, "Select * from memory order by time desc", "baeldung");
+
+        assertEquals(2, memoryPointList.size());
+        assertTrue(4743656L == memoryPointList.get(0).getFree());
+
+        // Clean up database
+        connection.deleteDatabase("baeldung");
+        connection.close();
+    }
+
+}

influxdb/src/test/resources/logback.xml

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

java-difference-date/pom.xml

@@ -41,6 +41,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.7.0</version>               
                 <configuration>
                     <target>1.8</target>
                     <target>1.8</target>