Merge remote-tracking branch 'baeldung/master' into BAEL-4288#flyway-repair

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

@@ -13,4 +13,4 @@ This module contains articles about core Java input and output (IO)
 - [How to Copy a File with Java](https://www.baeldung.com/java-copy-file)
 - [Create a Directory in Java](https://www.baeldung.com/java-create-directory) 
 - [Java IO vs NIO](https://www.baeldung.com/java-io-vs-nio)
-- [[<-- Prev]](/core-java-modules/core-java-io)
+- [[<-- Prev]](/core-java-modules/core-java-io)[[More -->]](/core-java-modules/core-java-io-3)

core-java-modules/core-java-io-3/README.md

@@ -0,0 +1,7 @@
+## Core Java IO
+
+This module contains articles about core Java input and output (IO)
+
+### Relevant Articles: 
+- [Java – Create a File](https://www.baeldung.com/java-how-to-create-a-file)
+- [[<-- Prev]](/core-java-modules/core-java-io-2)

core-java-modules/core-java-io-3/pom.xml

@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project
+    xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-io-3</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-io-3</name>
+    <packaging>jar</packaging>
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../</relativePath>
+    </parent>
+
+    <dependencies>
+        <!-- utils -->
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
+        <!-- utils -->
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
+        <!-- logging -->
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
+            <groupId>org.slf4j</groupId>
+            <artifactId>log4j-over-slf4j</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/com.github.tomakehurst/wiremock -->
+        <dependency>
+            <groupId>com.github.tomakehurst</groupId>
+            <artifactId>wiremock</artifactId>
+            <version>${wiremock.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+        <finalName>core-java-io-3</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-javadoc-plugin</artifactId>
+                <version>${maven-javadoc-plugin.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <assertj.version>3.6.1</assertj.version>
+        <maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
+        <wiremock.version>2.26.3</wiremock.version>
+    </properties>
+
+</project>

core-java-modules/core-java-io-3/src/test/java/com/baeldung/createfile/CreateFileUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.createfile;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class CreateFileUnitTest {
+
+    private final String FILE_NAME = "src/test/resources/fileToCreate.txt";
+
+    @AfterEach
+    @BeforeEach
+    public void cleanUpFiles() {
+        File targetFile = new File(FILE_NAME);
+        targetFile.delete();
+    }
+
+    @Test
+    public void givenUsingNio_whenCreatingFile_thenCorrect() throws IOException {
+        Path newFilePath = Paths.get(FILE_NAME);
+        Files.createFile(newFilePath);
+    }
+
+    @Test
+    public void givenUsingFile_whenCreatingFile_thenCorrect() throws IOException {
+        File newFile = new File(FILE_NAME);
+        boolean success = newFile.createNewFile();
+        assertTrue(success);
+    }
+
+    @Test
+    public void givenUsingGuava_whenCreatingFile_thenCorrect() throws IOException {
+        com.google.common.io.Files.touch(new File(FILE_NAME));
+    }
+
+    @Test
+    public void givenUsingCommonsIo_whenCreatingFile_thenCorrect() throws IOException {
+        FileUtils.touch(new File(FILE_NAME));
+    }
+
+}

core-java-modules/core-java-lang-3/src/main/java/com/baeldung/staticvariables/StaticVariableDemo.java

@@ -0,0 +1,23 @@
+package com.baeldung.staticvariables;
+
+public class StaticVariableDemo {
+    public static int i;
+    public static int j = 20;
+    public static int z;
+
+    static {
+        z = 30;
+        a = 40;
+    }
+
+    public static int a = 50;
+
+    public static final int b = 100;
+
+    public StaticVariableDemo() {
+    }
+
+    static class Nested {
+        public static String nestedClassStaticVariable = "test";
+    }
+}

core-java-modules/core-java-lang-3/src/test/java/com/baeldung/staticvariables/StaticVariableUnitTest.java

@@ -0,0 +1,113 @@
+package com.baeldung.staticvariables;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.lang.reflect.Field;
+
+import org.junit.jupiter.api.Test;
+
+public class StaticVariableUnitTest {
+
+    @Test
+    public void initializeStaticVariable_checkAssignedValues() {
+
+        try {
+            Class<?> staticVariableDemo = this.getClass()
+                .getClassLoader()
+                .loadClass("com.baeldung.staticvariables.StaticVariableDemo");
+
+            Field field1 = staticVariableDemo.getField("i");
+
+            assertThat(field1.getInt(staticVariableDemo)).isEqualTo(0);
+
+            Field field2 = staticVariableDemo.getField("j");
+
+            assertThat(field2.getInt(staticVariableDemo)).isEqualTo(20);
+
+        } catch (ClassNotFoundException | NoSuchFieldException | SecurityException e) {
+            e.printStackTrace();
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    @Test
+    public void initializeStaticVariable_checkStaticBlock() {
+
+        try {
+            Class<?> staticVariableDemo = this.getClass()
+                .getClassLoader()
+                .loadClass("com.baeldung.staticvariables.StaticVariableDemo");
+
+            Field field1 = staticVariableDemo.getField("z");
+
+            assertThat(field1.getInt(staticVariableDemo)).isEqualTo(30);
+
+            Field field2 = staticVariableDemo.getField("a");
+
+            assertThat(field2.getInt(staticVariableDemo)).isEqualTo(50);
+
+        } catch (ClassNotFoundException | NoSuchFieldException | SecurityException e) {
+            e.printStackTrace();
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    @Test
+    public void initializeStaticVariable_checkFinalValues() {
+
+        try {
+            Class<?> staticVariableDemo = this.getClass()
+                .getClassLoader()
+                .loadClass("com.baeldung.staticvariables.StaticVariableDemo");
+
+            Field field1 = staticVariableDemo.getField("b");
+
+            assertThat(field1.getInt(staticVariableDemo)).isEqualTo(100);
+
+        } catch (ClassNotFoundException | NoSuchFieldException | SecurityException e) {
+            e.printStackTrace();
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    @Test
+    public void initializeStaticVariable_checkInnerClassValues() {
+
+        try {
+            Class<?> staticVariableDemo = this.getClass()
+                .getClassLoader()
+                .loadClass("com.baeldung.staticvariables.StaticVariableDemo");
+
+            Class<?>[] nestedClasses = staticVariableDemo.getClasses();
+
+            for (Class<?> nestedClass : nestedClasses) {
+                if (nestedClass.getName()
+                    .equals("Nested")) {
+
+                    Field field1 = nestedClass.getField("nestedClassStaticVariable");
+                    assertThat(field1.get(nestedClass)).isEqualTo("test");
+                }
+            }
+
+        } catch (ClassNotFoundException | NoSuchFieldException | SecurityException e) {
+            e.printStackTrace();
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+
+    }
+}

core-java-modules/pom.xml

@@ -72,6 +72,7 @@
 
         <module>core-java-io</module>
         <module>core-java-io-2</module>
+        <module>core-java-io-3</module>
         <module>core-java-io-apis</module>
         <module>core-java-io-conversions</module>
         <module>core-java-io-conversions-2</module>

ddd/src/main/java/com/baeldung/ddd/order/config/CustomMongoConfiguration.java

@@ -0,0 +1,46 @@
+package com.baeldung.ddd.order.config;
+
+import org.bson.Document;
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.data.convert.ReadingConverter;
+import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
+
+import java.math.BigDecimal;
+import java.util.Collections;
+
+@Configuration
+public class CustomMongoConfiguration {
+
+    @Bean
+    public MongoCustomConversions customConversions() {
+        return new MongoCustomConversions(Collections.singletonList(DocumentToMoneyConverter.INSTANCE));
+    }
+
+    @ReadingConverter
+    enum DocumentToMoneyConverter implements Converter<Document, Money> {
+
+        INSTANCE;
+
+        @Override
+        public Money convert(Document source) {
+            Document money = source.get("money", Document.class);
+
+            return Money.of(getCurrency(money), getAmount(money));
+        }
+
+        private CurrencyUnit getCurrency(Document money) {
+            Document currency = money.get("currency", Document.class);
+            String currencyCode = currency.getString("code");
+            return CurrencyUnit.of(currencyCode);
+        }
+
+        private BigDecimal getAmount(Document money) {
+            String amount = money.getString("amount");
+            return BigDecimal.valueOf(Double.parseDouble(amount));
+        }
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/jpa/PersistOrderLiveTest.java

@@ -1,19 +1,24 @@
 package com.baeldung.ddd.order.jpa;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
-import java.math.BigDecimal;
-import java.util.Arrays;
-
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
 
+import java.math.BigDecimal;
+import java.util.Arrays;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/*
+ To run this test we need to run the databases first.
+ A dedicated docker-compose.yml file is located under the resources directory.
+ We can run it by simple executing `docker-compose up`.
+ */
 @SpringJUnitConfig
 @SpringBootTest
-public class PersistOrderIntegrationTest {
+public class PersistOrderLiveTest {
     @Autowired
     private JpaOrderRepository repository;
 

ddd/src/test/java/com/baeldung/ddd/order/mongo/OrderMongoLiveTest.java

@@ -17,9 +17,14 @@ import com.baeldung.ddd.order.Order;
 import com.baeldung.ddd.order.OrderLine;
 import com.baeldung.ddd.order.Product;
 
+/*
+ To run this test we need to run the databases first.
+ A dedicated docker-compose.yml file is located under the resources directory.
+ We can run it by simple executing `docker-compose up`.
+ */
 @SpringJUnitConfig
 @SpringBootTest
-public class OrderMongoIntegrationTest {
+public class OrderMongoLiveTest {
     @Autowired
     private OrderMongoRepository repo;
 

ddd/src/test/java/com/baeldung/dddhexagonalspring/infrastracture/repository/CassandraDbOrderRepositoryLiveTest.java

@@ -18,10 +18,15 @@ import com.baeldung.dddhexagonalspring.domain.Product;
 import com.baeldung.dddhexagonalspring.domain.repository.OrderRepository;
 import com.baeldung.dddhexagonalspring.infrastracture.repository.cassandra.SpringDataCassandraOrderRepository;
 
+/*
+ To run this test we need to run the databases first.
+ A dedicated docker-compose.yml file is located under the resources directory.
+ We can run it by simple executing `docker-compose up`.
+ */
 @SpringJUnitConfig
 @SpringBootTest
 @TestPropertySource("classpath:ddd-layers-test.properties")
-class CassandraDbOrderRepositoryIntegrationTest {
+class CassandraDbOrderRepositoryLiveTest {
 
     @Autowired
     private SpringDataCassandraOrderRepository cassandraOrderRepository;

ddd/src/test/java/com/baeldung/dddhexagonalspring/infrastracture/repository/MongoDbOrderRepositoryLiveTest.java

@@ -18,10 +18,15 @@ import com.baeldung.dddhexagonalspring.domain.Product;
 import com.baeldung.dddhexagonalspring.domain.repository.OrderRepository;
 import com.baeldung.dddhexagonalspring.infrastracture.repository.mongo.SpringDataMongoOrderRepository;
 
+/*
+ To run this test we need to run the databases first.
+ A dedicated docker-compose.yml file is located under the resources directory.
+ We can run it by simple executing `docker-compose up`.
+ */
 @SpringJUnitConfig
 @SpringBootTest
 @TestPropertySource("classpath:ddd-layers-test.properties")
-class MongoDbOrderRepositoryIntegrationTest {
+class MongoDbOrderRepositoryLiveTest {
 
     @Autowired
     private SpringDataMongoOrderRepository mongoOrderRepository;

libraries-6/README.md

@@ -15,4 +15,5 @@ Remember, for advanced libraries like [Jackson](/jackson) and [JUnit](/testing-m
 - [A Guide to the Reflections Library](https://www.baeldung.com/reflections-library)
 - [Exactly Once Processing in Kafka](https://www.baeldung.com/kafka-exactly-once)
 - [Introduction to Protonpack](https://www.baeldung.com/java-protonpack)
+- [Java-R Integration](https://www.baeldung.com/java-r-integration)
 - More articles [[<-- prev]](/libraries-5)

libraries-6/pom.xml

@@ -92,8 +92,50 @@
             <version>${commonsio.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.rosuda.REngine</groupId>
+            <artifactId>Rserve</artifactId>
+            <version>${rserve.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.github.jbytecode</groupId>
+            <artifactId>RCaller</artifactId>
+            <version>${rcaller.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.renjin</groupId>
+            <artifactId>renjin-script-engine</artifactId>
+            <version>${renjin.version}</version>
+        </dependency>
     </dependencies>
 
+    <repositories>
+        <!-- Needed for Renjin -->
+        <repository>
+            <id>bedatadriven</id>
+            <name>bedatadriven public repo</name>
+            <url>https://nexus.bedatadriven.com/content/groups/public/</url>
+        </repository>
+    </repositories>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <!-- Excludes FastR classes from compilations since they require GraalVM -->
+                    <excludes>
+                        <exclude>com/baeldung/r/FastRMean.java</exclude>
+                    </excludes>
+                    <testExcludes>
+                        <exclude>com/baeldung/r/FastRMeanUnitTest.java</exclude>
+                    </testExcludes>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
     <properties>
         <kafka.version>2.0.0</kafka.version>
         <javapoet.version>1.10.0</javapoet.version>
@@ -105,6 +147,9 @@
         <commons-net.version>3.6</commons-net.version>
         <assertj.version>3.6.2</assertj.version>
         <commonsio.version>2.6</commonsio.version>
+        <renjin.version>RELEASE</renjin.version>
+        <rcaller.version>3.0</rcaller.version>
+        <rserve.version>1.8.1</rserve.version>
     </properties>
 
 

libraries-6/src/main/java/com/baeldung/r/FastRMean.java

@@ -1,8 +1,5 @@
 package com.baeldung.r;
 
-import java.io.IOException;
-import java.net.URISyntaxException;
-
 /**
  * FastR showcase.
  * 

libraries-6/src/main/java/com/baeldung/r/RCallerMean.java

@@ -1,12 +1,12 @@
 package com.baeldung.r;
 
-import java.io.IOException;
-import java.net.URISyntaxException;
-
 import com.github.rcaller.rstuff.RCaller;
 import com.github.rcaller.rstuff.RCallerOptions;
 import com.github.rcaller.rstuff.RCode;
 
+import java.io.IOException;
+import java.net.URISyntaxException;
+
 /**
  * RCaller showcase.
  * 

libraries-6/src/main/java/com/baeldung/r/RenjinMean.java

@@ -1,13 +1,12 @@
 package com.baeldung.r;
 
-import java.io.IOException;
-import java.net.URISyntaxException;
-
-import javax.script.ScriptException;
-
 import org.renjin.script.RenjinScriptEngine;
 import org.renjin.sexp.DoubleArrayVector;
 
+import javax.script.ScriptException;
+import java.io.IOException;
+import java.net.URISyntaxException;
+
 /**
  * Renjin showcase.
  * 

libraries-6/src/test/java/com/baeldung/r/RCallerMeanIntegrationTest.java

@@ -1,14 +1,13 @@
 package com.baeldung.r;
 
-import java.io.IOException;
-import java.net.URISyntaxException;
-
-import javax.script.ScriptException;
-
 import org.junit.Assert;
 import org.junit.Ignore;
 import org.junit.Test;
 
+import javax.script.ScriptException;
+import java.io.IOException;
+import java.net.URISyntaxException;
+
 /**
  * Test for {@link RCallerMean}.
  * 

libraries-6/src/test/java/com/baeldung/r/RenjinMeanUnitTest.java

@@ -1,13 +1,11 @@
 package com.baeldung.r;
 
-import java.io.IOException;
+import org.junit.Assert;
-import java.net.URISyntaxException;
-
-import javax.script.ScriptException;
-
 import org.junit.Test;
 
-import org.junit.Assert;
+import javax.script.ScriptException;
+import java.io.IOException;
+import java.net.URISyntaxException;
 
 /**
  * Test for {@link RenjinMean}.

libraries-data-2/README.md

@@ -8,10 +8,8 @@ This module contains articles about libraries for data processing in Java.
 - [Introduction to Conflict-Free Replicated Data Types](https://www.baeldung.com/java-conflict-free-replicated-data-types)
 - [Introduction to javax.measure](https://www.baeldung.com/javax-measure)
 - [A Guide to Infinispan in Java](https://www.baeldung.com/infinispan)
-- [Guide to JMapper](https://www.baeldung.com/jmapper)
 - [An Introduction to SuanShu](https://www.baeldung.com/suanshu)
 - [Intro to Derive4J](https://www.baeldung.com/derive4j)
-- [Java-R Integration](https://www.baeldung.com/java-r-integration)
 - [Univocity Parsers](https://www.baeldung.com/java-univocity-parsers)
 - [Using Kafka MockConsumer](https://www.baeldung.com/kafka-mockconsumer)
 - [Using Kafka MockProducer](https://www.baeldung.com/kafka-mockproducer)

libraries-data-2/pom.xml

@@ -86,11 +86,6 @@
             <artifactId>spring-web</artifactId>
             <version>${spring.version}</version>
         </dependency>
-        <dependency>
-            <groupId>com.googlecode.jmapper-framework</groupId>
-            <artifactId>jmapper-core</artifactId>
-            <version>${jmapper.version}</version>
-        </dependency>
         <dependency>
             <groupId>com.numericalmethod</groupId>
             <artifactId>suanshu</artifactId>
@@ -126,6 +121,11 @@
             <artifactId>kafka-clients</artifactId>
             <version>${kafka.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.awaitility</groupId>
             <artifactId>awaitility</artifactId>
@@ -138,21 +138,6 @@
             <version>${awaitility.version}</version>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.rosuda.REngine</groupId>
-            <artifactId>Rserve</artifactId>
-            <version>${rserve.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>com.github.jbytecode</groupId>
-            <artifactId>RCaller</artifactId>
-            <version>${rcaller.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.renjin</groupId>
-            <artifactId>renjin-script-engine</artifactId>
-            <version>${renjin.version}</version>
-        </dependency>
         <dependency>
             <groupId>net.bytebuddy</groupId>
             <artifactId>byte-buddy</artifactId>
@@ -175,33 +160,8 @@
             <url>http://repo.numericalmethod.com/maven/</url>
             <layout>default</layout>
         </repository>
-        
-        <!-- Needed for Renjin -->
-        <repository>
-            <id>bedatadriven</id>
-            <name>bedatadriven public repo</name>
-            <url>https://nexus.bedatadriven.com/content/groups/public/</url>
-        </repository>
     </repositories>
 
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
-                <configuration>
-                    <!-- Excludes FastR classes from compilations since they require GraalVM -->
-                    <excludes>
-                        <exclude>com/baeldung/r/FastRMean.java</exclude>
-                    </excludes>
-                    <testExcludes>
-                        <exclude>com/baeldung/r/FastRMeanUnitTest.java</exclude>						
-                    </testExcludes>
-                </configuration>
-            </plugin>
-        </plugins>
-    </build>
-
     <properties>
         <flink.version>1.5.0</flink.version>
         <hll.version>1.6.0</hll.version>
@@ -210,17 +170,14 @@
         <infinispan.version>9.1.5.Final</infinispan.version>
         <jackson.version>2.9.8</jackson.version>
         <spring.version>4.3.8.RELEASE</spring.version>
-        <jmapper.version>1.6.0.1</jmapper.version>
         <suanshu.version>4.0.0</suanshu.version>
         <derive4j.version>1.1.0</derive4j.version>
         <assertj.version>3.6.2</assertj.version>
         <slf4j.version>1.7.25</slf4j.version>
         <awaitility.version>3.0.0</awaitility.version>
         <univocity.version>2.8.4</univocity.version>
-        <renjin.version>RELEASE</renjin.version>
-        <rcaller.version>3.0</rcaller.version>
-        <rserve.version>1.8.1</rserve.version>
         <kafka.version>2.5.0</kafka.version>
+        <guava.version>29.0-jre</guava.version>
     </properties>
 
 </project>

libraries-data/README.md

@@ -12,4 +12,5 @@ This module contains articles about libraries for data processing in Java.
 - [Introduction to Kafka Connectors](https://www.baeldung.com/kafka-connectors-guide)
 - [Kafka Connect Example with MQTT and MongoDB](https://www.baeldung.com/kafka-connect-mqtt-mongodb)
 - [Building a Data Pipeline with Flink and Kafka](https://www.baeldung.com/kafka-flink-data-pipeline)
+- [Guide to JMapper](https://www.baeldung.com/jmapper)
 More articles: [[next -->]](/../libraries-data-2)

libraries-data/pom.xml

@@ -126,6 +126,11 @@
                 </exclusion>
             </exclusions>
         </dependency>
+        <dependency>
+            <groupId>com.googlecode.jmapper-framework</groupId>
+            <artifactId>jmapper-core</artifactId>
+            <version>${jmapper.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -172,6 +177,7 @@
         <org.apache.crunch.crunch-core.version>0.15.0</org.apache.crunch.crunch-core.version>
         <org.apache.hadoop.hadoop-client>2.2.0</org.apache.hadoop.hadoop-client>
         <slf4j.version>1.7.25</slf4j.version>
+        <jmapper.version>1.6.0.1</jmapper.version>
     </properties>
 
 </project>

libraries-data/src/test/java/com/baeldung/jmapper/JMapperIntegrationTest.java

@@ -7,6 +7,9 @@ import org.junit.Test;
 import java.time.LocalDate;
 
 import static com.googlecode.jmapper.api.JMapperAPI.*;
+import static com.googlecode.jmapper.api.JMapperAPI.attribute;
+import static com.googlecode.jmapper.api.JMapperAPI.global;
+import static com.googlecode.jmapper.api.JMapperAPI.mappedClass;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 

patterns/hexagonal-architecture/pom.xml

@@ -0,0 +1,59 @@
+<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>2.3.0.RELEASE</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
+	<groupId>com.baeldung</groupId>
+	<artifactId>hexagonal-architecture</artifactId>
+	<version>1.0</version>
+	<name>hexagonal-architecture</name>
+	<description>Project for hexagonal architecture in java</description>
+
+	<properties>
+		<java.version>1.8</java.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-web</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-mongodb</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+			<exclusions>
+				<exclusion>
+					<groupId>org.junit.vintage</groupId>
+					<artifactId>junit-vintage-engine</artifactId>
+				</exclusion>
+			</exclusions>
+		</dependency>
+		<dependency>
+			<groupId>org.mockito</groupId>
+			<artifactId>mockito-core</artifactId>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

patterns/hexagonal-architecture/src/main/java/com/baeldung/pattern/hexagonal/HexArchApplicationDemo.java

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

patterns/hexagonal-architecture/src/main/java/com/baeldung/pattern/hexagonal/config/AppConfig.java

@@ -0,0 +1,15 @@
+package com.baeldung.pattern.hexagonal.config;
+
+import com.baeldung.pattern.hexagonal.domain.services.EmployeeService;
+import com.baeldung.pattern.hexagonal.domain.services.EmployeeServiceImpl;
+import com.baeldung.pattern.hexagonal.persistence.EmployeeRepository;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class AppConfig {
+    @Bean
+    public EmployeeService getEmployeeService(EmployeeRepository employeeRepository) {
+        return new EmployeeServiceImpl(employeeRepository);
+    }
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/pattern/hexagonal/config/MongoConfig.java

@@ -0,0 +1,10 @@
+package com.baeldung.pattern.hexagonal.config;
+
+import com.baeldung.pattern.hexagonal.persistence.MongoRepoEx;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;
+
+@Configuration
+@EnableMongoRepositories(basePackageClasses = MongoRepoEx.class)
+public class MongoConfig {
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/pattern/hexagonal/controller/EmployeeController.java

@@ -0,0 +1,25 @@
+package com.baeldung.pattern.hexagonal.controller;
+
+import com.baeldung.pattern.hexagonal.domain.model.Employee;
+import com.baeldung.pattern.hexagonal.domain.services.EmployeeService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.MediaType;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/employees")
+public class EmployeeController {
+    @Autowired
+    EmployeeService employeeService;
+
+    @PostMapping(produces = MediaType.APPLICATION_JSON_VALUE, consumes = MediaType.APPLICATION_JSON_VALUE)
+    @ResponseBody
+    public Employee addEmployee(@RequestBody Employee employee) {
+        return employeeService.addEmployee(employee);
+    }
+
+    @GetMapping(path = "/{employeeId}")
+    public Employee getEmployee(@PathVariable("employeeId") String employeeId) {
+        return employeeService.getEmployee(employeeId);
+    }
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/pattern/hexagonal/domain/model/Employee.java

@@ -0,0 +1,51 @@
+package com.baeldung.pattern.hexagonal.domain.model;
+
+import org.springframework.data.annotation.Id;
+
+import java.util.Objects;
+
+public class Employee {
+    @Id
+    private String empId;
+    private String empName;
+    private String empJobTitle;
+
+    public String getEmpId() {
+        return empId;
+    }
+
+    public void setEmpId(String empId) {
+        this.empId = empId;
+    }
+
+    public String getEmpName() {
+        return empName;
+    }
+
+    public void setEmpName(String empName) {
+        this.empName = empName;
+    }
+
+    public String getEmpJobTitle() {
+        return empJobTitle;
+    }
+
+    public void setEmpJobTitle(String empJobTitle) {
+        this.empJobTitle = empJobTitle;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Employee employee = (Employee) o;
+        return empId.equals(employee.empId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(empId);
+    }
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/pattern/hexagonal/domain/services/EmployeeService.java

@@ -0,0 +1,10 @@
+package com.baeldung.pattern.hexagonal.domain.services;
+
+import com.baeldung.pattern.hexagonal.domain.model.Employee;
+
+public interface EmployeeService {
+
+    Employee addEmployee(Employee employee);
+
+    Employee getEmployee(String employeeId);
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/pattern/hexagonal/domain/services/EmployeeServiceImpl.java

@@ -0,0 +1,34 @@
+package com.baeldung.pattern.hexagonal.domain.services;
+
+import com.baeldung.pattern.hexagonal.domain.model.Employee;
+import com.baeldung.pattern.hexagonal.persistence.EmployeeRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+
+import java.util.Optional;
+
+public class EmployeeServiceImpl implements EmployeeService {
+
+    private EmployeeRepository employeeRepository;
+
+    @Autowired
+    public EmployeeServiceImpl(EmployeeRepository employeeRepository) {
+        this.employeeRepository = employeeRepository;
+    }
+
+    @Override
+    public Employee addEmployee(Employee employee) {
+        return employeeRepository.add(employee);
+    }
+
+    @Override
+    public Employee getEmployee(String employeeId) {
+        Optional<Employee> employee = employeeRepository.findById(employeeId);
+
+        if (employee.isPresent()) {
+            return employee.get();
+        } else {
+            // throw
+        }
+        return null;
+    }
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/pattern/hexagonal/persistence/EmployeeRepository.java

@@ -0,0 +1,15 @@
+package com.baeldung.pattern.hexagonal.persistence;
+
+import com.baeldung.pattern.hexagonal.domain.model.Employee;
+import org.springframework.stereotype.Repository;
+
+import java.util.Optional;
+
+@Repository
+public interface EmployeeRepository {
+
+    Employee add(Employee employee);
+
+    Optional<Employee> findById(String id);
+
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/pattern/hexagonal/persistence/MongoDBRepository.java

@@ -0,0 +1,24 @@
+package com.baeldung.pattern.hexagonal.persistence;
+
+import com.baeldung.pattern.hexagonal.domain.model.Employee;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Repository;
+
+import java.util.Optional;
+
+@Repository
+public class MongoDBRepository implements EmployeeRepository {
+
+    @Autowired
+    MongoRepoEx mongoRepository;
+
+    @Override
+    public Employee add(Employee employee) {
+        return mongoRepository.insert(employee);
+    }
+
+    @Override
+    public Optional<Employee> findById(String id) {
+        return mongoRepository.findById(id);
+    }
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/pattern/hexagonal/persistence/MongoRepoEx.java

@@ -0,0 +1,9 @@
+package com.baeldung.pattern.hexagonal.persistence;
+
+import com.baeldung.pattern.hexagonal.domain.model.Employee;
+import org.springframework.data.mongodb.repository.MongoRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface MongoRepoEx extends MongoRepository<Employee, String> {
+}

patterns/hexagonal-architecture/src/main/resources/application.properties

@@ -0,0 +1 @@
+

patterns/hexagonal-architecture/src/test/java/com/baeldung/pattern/hexagonal/domain/services/EmployeeServiceImplTest.java

@@ -0,0 +1,46 @@
+package com.baeldung.pattern.hexagonal.domain.services;
+
+import com.baeldung.pattern.hexagonal.domain.model.Employee;
+import com.baeldung.pattern.hexagonal.persistence.EmployeeRepository;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class EmployeeServiceImplTest {
+
+    private EmployeeRepository employeeRepository;
+    private EmployeeService testService;
+    private Employee testModel;
+
+    @BeforeEach
+    void setUp() {
+        employeeRepository = mock(EmployeeRepository.class);
+
+        testService = new EmployeeServiceImpl(employeeRepository);
+        testModel = new Employee();
+        testModel.setEmpId("2000");
+        testModel.setEmpName("Test user 1");
+        testModel.setEmpJobTitle("Software engineer");
+    }
+
+    @Test
+    void addEmployee() {
+        when(employeeRepository.add(any(Employee.class))).thenReturn(testModel);
+
+        Employee testResponse = testService.addEmployee(testModel);
+        assertEquals(testModel, testResponse);
+    }
+
+    @Test
+    void getEmployee() {
+        when(employeeRepository.findById("2000")).thenReturn(Optional.of(testModel));
+
+        Employee testResponse = testService.getEmployee("2000");
+        assertEquals(testModel, testResponse);
+    }
+}

persistence-modules/core-java-persistence/src/main/java/com/baeldung/statmentVsPreparedstatment/DatasourceFactory.java

@@ -0,0 +1,23 @@
+package com.baeldung.statmentVsPreparedstatment;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+
+public class DatasourceFactory {
+
+    private Connection connection;
+
+    public Connection getConnection() throws ClassNotFoundException, SQLException {
+        Class.forName("org.h2.Driver");
+        connection = DriverManager.getConnection("jdbc:h2:mem:db_basic", "SA", "");
+        connection.setAutoCommit(false);
+        return connection;
+    }
+
+    public boolean createTables() throws SQLException {
+        String query = "create table if not exists PERSONS (ID INT, NAME VARCHAR(45))";
+        return connection.createStatement().executeUpdate(query) == 0;
+    }
+
+}

persistence-modules/core-java-persistence/src/main/java/com/baeldung/statmentVsPreparedstatment/PersonEntity.java

@@ -0,0 +1,42 @@
+package com.baeldung.statmentVsPreparedstatment;
+
+import java.util.Objects;
+
+public class PersonEntity {
+    private int id;
+    private String name;
+
+    public PersonEntity(int id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    @Override public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        PersonEntity that = (PersonEntity) o;
+        return id == that.id && Objects.equals(name, that.name);
+    }
+
+    @Override public int hashCode() {
+        return Objects.hash(id, name);
+    }
+}

persistence-modules/core-java-persistence/src/main/java/com/baeldung/statmentVsPreparedstatment/PreparedStatementPersonDao.java

@@ -0,0 +1,88 @@
+package com.baeldung.statmentVsPreparedstatment;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+
+public class PreparedStatementPersonDao {
+
+    private final Connection connection;
+
+    public PreparedStatementPersonDao(Connection connection) {
+        this.connection = connection;
+    }
+
+    public Optional<PersonEntity> getById(int id) throws SQLException {
+        String query = "SELECT id, name FROM persons WHERE id = ?";
+
+        PreparedStatement preparedStatement = connection.prepareStatement(query);
+        preparedStatement.setInt(1, id);
+        ResultSet resultSet = preparedStatement.executeQuery();
+
+        if (resultSet.first()) {
+
+            PersonEntity result = new PersonEntity(resultSet.getInt("id"),
+                resultSet.getString("name"));
+
+            return Optional.of(result);
+        } else {
+            return Optional.empty();
+        }
+
+    }
+
+    public void insert(PersonEntity personEntity) throws SQLException {
+
+        String query = "INSERT INTO persons(id, name) VALUES( ?, ?)";
+
+        PreparedStatement preparedStatement = connection.prepareStatement(query);
+        preparedStatement.setInt(1, personEntity.getId());
+        preparedStatement.setString(2, personEntity.getName());
+        preparedStatement.executeUpdate();
+
+    }
+
+    public void insert(List<PersonEntity> personEntities) throws SQLException {
+        String query = "INSERT INTO persons(id, name) VALUES( ?, ?)";
+
+        PreparedStatement preparedStatement = connection.prepareStatement(query);
+        for (PersonEntity personEntity : personEntities) {
+            preparedStatement.setInt(1, personEntity.getId());
+            preparedStatement.setString(2, personEntity.getName());
+            preparedStatement.addBatch();
+        }
+        preparedStatement.executeBatch();
+
+    }
+
+    public void update(PersonEntity personEntity) throws SQLException {
+        String query = "UPDATE persons SET name = ? WHERE id = ?";
+        PreparedStatement preparedStatement = connection.prepareStatement(query);
+        preparedStatement.setString(1, personEntity.getName());
+        preparedStatement.setInt(2, personEntity.getId());
+        preparedStatement.executeUpdate();
+    }
+
+    public void deleteById(int id) throws SQLException {
+        String query = "DELETE FROM persons WHERE id = ?";
+        PreparedStatement preparedStatement = connection.prepareStatement(query);
+        preparedStatement.setInt(1, id);
+        preparedStatement.executeUpdate();
+    }
+
+    public List<PersonEntity> getAll() throws SQLException {
+        String query = "SELECT id, name FROM persons";
+
+        PreparedStatement preparedStatement = connection.prepareStatement(query);
+        ResultSet resultSet = preparedStatement.executeQuery();
+        List<PersonEntity> result = new ArrayList<>();
+        while (resultSet.next()) {
+            result.add(new PersonEntity(resultSet.getInt("id"), resultSet.getString("name")));
+        }
+        return result;
+    }
+}

persistence-modules/core-java-persistence/src/main/java/com/baeldung/statmentVsPreparedstatment/StatementPersonDao.java

@@ -0,0 +1,75 @@
+package com.baeldung.statmentVsPreparedstatment;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+
+public class StatementPersonDao {
+
+    private final Connection connection;
+
+    public StatementPersonDao(Connection connection) {
+        this.connection = connection;
+    }
+
+    public Optional<PersonEntity> getById(int id) throws SQLException {
+        String query = "SELECT id, name, FROM persons WHERE id = '" + id + "'";
+
+        Statement statement = connection.createStatement();
+        ResultSet resultSet = statement.executeQuery(query);
+
+        if (resultSet.first()) {
+            PersonEntity result = new PersonEntity(resultSet.getInt("id"),
+                resultSet.getString("name"));
+            return Optional.of(result);
+        } else {
+            return Optional.empty();
+        }
+    }
+
+    public void insert(PersonEntity personEntity) throws SQLException {
+        String query = "INSERT INTO persons(id, name) VALUES(" + personEntity.getId() + ", '"
+            + personEntity.getName() + "')";
+
+        Statement statement = connection.createStatement();
+        statement.executeUpdate(query);
+    }
+
+    public void insert(List<PersonEntity> personEntities) throws SQLException {
+        for (PersonEntity personEntity : personEntities) {
+            insert(personEntity);
+        }
+    }
+
+    public void update(PersonEntity personEntity) throws SQLException {
+
+        String query = "UPDATE persons SET name = '" + personEntity.getName() + "' WHERE id = "
+            + personEntity.getId();
+
+        Statement statement = connection.createStatement();
+        statement.executeUpdate(query);
+
+    }
+
+    public void deleteById(int id) throws SQLException {
+        String query = "DELETE FROM persons WHERE id = " + id;
+        Statement statement = connection.createStatement();
+        statement.executeUpdate(query);
+    }
+
+    public List<PersonEntity> getAll() throws SQLException {
+        String query = "SELECT id, name, FROM persons";
+
+        Statement statement = connection.createStatement();
+        ResultSet resultSet = statement.executeQuery(query);
+        List<PersonEntity> result = new ArrayList<>();
+        while (resultSet.next()) {
+            result.add(new PersonEntity(resultSet.getInt("id"), resultSet.getString("name")));
+        }
+        return result;
+    }
+}

persistence-modules/core-java-persistence/src/test/java/com/baeldung/statmentVsPreparedstatment/DatasourceFactoryUnitTest.java

@@ -0,0 +1,22 @@
+package com.baeldung.statmentVsPreparedstatment;
+
+import org.junit.jupiter.api.Test;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class DatasourceFactoryUnitTest {
+
+    @Test
+    void whenCreateConnectionAndTables_thenConnectionIsOpenAndTableIsCreated()
+        throws SQLException, ClassNotFoundException {
+        DatasourceFactory factory = new DatasourceFactory();
+        Connection connection = factory.getConnection();
+
+        assertFalse(connection.isClosed());
+        assertTrue(factory.createTables());
+    }
+}

persistence-modules/core-java-persistence/src/test/java/com/baeldung/statmentVsPreparedstatment/PreparedStatementPersonDaoUnitTest.java

@@ -0,0 +1,94 @@
+package com.baeldung.statmentVsPreparedstatment;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class PreparedStatementPersonDaoUnitTest {
+    private PreparedStatementPersonDao dao;
+
+    @BeforeEach
+    void setup() throws SQLException, ClassNotFoundException {
+        DatasourceFactory datasourceFactory = new DatasourceFactory();
+        Connection connection = datasourceFactory.getConnection();
+        datasourceFactory.createTables();
+        dao = new PreparedStatementPersonDao(connection);
+    }
+
+    @Test
+    void whenInsertAPerson_thenItNeverThrowsAnException() {
+        assertDoesNotThrow(() -> dao.insert(new PersonEntity(1, "john")));
+    }
+
+    @Test
+    void whenInsertAPersonWithQuoteInText_thenItNeverThrowsAnException() {
+        assertDoesNotThrow(() -> dao.insert(new PersonEntity(1, "O'Brien")));
+    }
+
+    @Test
+    void whenGetAPersonById_thenItReturnThePersonInDatabase() throws SQLException {
+        dao.insert(new PersonEntity(1, "john"));
+
+        Optional<PersonEntity> maybeEmployee = dao.getById(1);
+        assertTrue(maybeEmployee.isPresent());
+
+        PersonEntity personEntity = maybeEmployee.get();
+
+        assertEquals(1, personEntity.getId());
+        assertEquals("john", personEntity.getName());
+    }
+
+    @Test
+    void whenInsertAndGetMultiplePersons_thenItNeverThrowsAnException() throws SQLException {
+        assertDoesNotThrow(() -> dao.insert(
+            Arrays.asList(new PersonEntity(1, "john"), new PersonEntity(2, "skit"))));
+
+        List<PersonEntity> result = dao.getAll();
+
+        assertEquals(Arrays.asList(new PersonEntity(1, "john"), new PersonEntity(2, "skit")),
+            result);
+    }
+
+    @Test
+    void whenUpdateAnExistentPerson_thenItReturnsTheUpdatedPerson() throws SQLException {
+        dao.insert(new PersonEntity(1, "john"));
+        dao.update(new PersonEntity(1, "johnny"));
+
+        Optional<PersonEntity> maybePerson = dao.getById(1);
+
+        assertTrue(maybePerson.isPresent());
+
+        PersonEntity personEntity = maybePerson.get();
+
+        assertEquals(1, personEntity.getId());
+        assertEquals("johnny", personEntity.getName());
+    }
+
+    @Test
+    void whenDeleteAPersonById_thenItWillBeAbsentInDatabase() throws SQLException {
+        dao.insert(new PersonEntity(1, "john"));
+        dao.deleteById(1);
+
+        Optional<PersonEntity> maybePerson = dao.getById(1);
+
+        assertFalse(maybePerson.isPresent());
+    }
+
+    @Test
+    void whenAHackerUpdateAPerson_thenItUpdatesTheTargetPerson() throws SQLException {
+        dao.insert(Arrays.asList(new PersonEntity(1, "john"), new PersonEntity(2, "skeet")));
+        dao.update(new PersonEntity(1, "hacker' --"));
+
+        List<PersonEntity> result = dao.getAll();
+
+        assertEquals(Arrays.asList(new PersonEntity(1, "hacker' --"), new PersonEntity(2, "skeet")),
+            result);
+    }
+}

persistence-modules/core-java-persistence/src/test/java/com/baeldung/statmentVsPreparedstatment/StatementPersonDaoUnitTest.java

@@ -0,0 +1,96 @@
+package com.baeldung.statmentVsPreparedstatment;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class StatementPersonDaoUnitTest {
+
+    private StatementPersonDao dao;
+
+    @BeforeEach
+    void setup() throws SQLException, ClassNotFoundException {
+        DatasourceFactory datasourceFactory = new DatasourceFactory();
+        Connection connection = datasourceFactory.getConnection();
+        datasourceFactory.createTables();
+        dao = new StatementPersonDao(connection);
+    }
+
+    @Test
+    void whenInsertAPerson_thenItNeverThrowsAnException() {
+        assertDoesNotThrow(() -> dao.insert(new PersonEntity(1, "john")));
+    }
+
+    @Test
+    void whenInsertAPersonWithQuoteInText_thenItWillThrowAnException() {
+        assertThrows(SQLException.class, () -> dao.insert(new PersonEntity(1, "O'Brien")));
+    }
+
+    @Test
+    void whenGetAPersonById_thenItReturnThePersonInDatabase() throws SQLException {
+        dao.insert(new PersonEntity(1, "john"));
+
+        Optional<PersonEntity> maybeEmployee = dao.getById(1);
+
+        assertTrue(maybeEmployee.isPresent());
+
+        PersonEntity personEntity = maybeEmployee.get();
+
+        assertEquals(1, personEntity.getId());
+        assertEquals("john", personEntity.getName());
+    }
+
+    @Test
+    void whenInsertAndGetMultiplePersons_thenItNeverThrowsAnException() throws SQLException {
+        assertDoesNotThrow(() -> dao.insert(
+            Arrays.asList(new PersonEntity(1, "john"), new PersonEntity(2, "skeet"))));
+
+        List<PersonEntity> result = dao.getAll();
+
+        assertEquals(Arrays.asList(new PersonEntity(1, "john"), new PersonEntity(2, "skeet")),
+            result);
+    }
+
+    @Test
+    void whenUpdateAnExistentPerson_thenItReturnsTheUpdatedPerson() throws SQLException {
+        dao.insert(new PersonEntity(1, "john"));
+        dao.update(new PersonEntity(1, "johnny"));
+
+        Optional<PersonEntity> maybePerson = dao.getById(1);
+
+        assertTrue(maybePerson.isPresent());
+
+        PersonEntity personEntity = maybePerson.get();
+
+        assertEquals(1, personEntity.getId());
+        assertEquals("johnny", personEntity.getName());
+    }
+
+    @Test
+    void whenDeleteAPersonById_thenItWillBeAbsentInDatabase() throws SQLException {
+        dao.insert(new PersonEntity(1, "john"));
+        dao.deleteById(1);
+
+        Optional<PersonEntity> maybePerson = dao.getById(1);
+
+        assertFalse(maybePerson.isPresent());
+    }
+
+    @Test
+    void whenAHackerUpdateAPerson_thenItAllPersonsAreUpdated() throws SQLException {
+        dao.insert(Arrays.asList(new PersonEntity(1, "john"), new PersonEntity(2, "skeet")));
+        dao.update(new PersonEntity(1, "hacker' --"));
+
+        List<PersonEntity> result = dao.getAll();
+
+        assertEquals(Arrays.asList(new PersonEntity(1, "hacker"), new PersonEntity(2, "hacker")),
+            result);
+    }
+}

testing-modules/junit-4/src/test/java/com/baeldung/assume/ConditionallyIgnoreTestsUnitTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.assume;
+
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assume.assumeFalse;
+import static org.junit.Assume.assumeThat;
+import static org.junit.Assume.assumeTrue;
+
+import org.junit.Test;
+
+public class ConditionallyIgnoreTestsUnitTest {
+
+
+    @Test
+    public void whenAssumeThatCodeVersionIsNot2_thenIgnore() {
+        final int codeVersion = 1;
+        assumeThat(codeVersion, is(2));
+
+        assertEquals("hello", "HELLO".toLowerCase());
+    }
+
+    @Test
+    public void whenAssumeTrueOnCondition_thenIgnore() {
+        final int codeVersion = 1;
+        assumeTrue(isCodeVersion2(codeVersion));
+
+        assertEquals("hello", "HELLO".toLowerCase());
+    }
+
+    @Test
+    public void whenAssumeFalseOnCondition_thenIgnore() {
+        final int codeVersion = 2;
+        assumeFalse(isCodeVersion2(codeVersion));
+
+        assertEquals("hello", "HELLO".toLowerCase());
+    }
+
+    private boolean isCodeVersion2(final int codeVersion) {
+        return codeVersion == 2;
+    }
+}