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BAEL-4135 - When are static variables initialized? (eugenp#9607)
* Hexagonal Architecture in Java A quick and practical example of Hexagonal Architecture in Java * Fixed code formatting issues * When are static variables initialized Sample class and test class. * Revert "When are static variables initialized" This reverts commit c781923. * Revert "Revert "When are static variables initialized"" This reverts commit 2bffdf4. * New java module for static variable Created a new core-java-lang-3 module for static variables. * PR review changes: Added more scenarios to the static variable test Covered the following cases: 1. Variable initialization in a static block 2. Variable initialization in a static nested class
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‎core-java-modules/core-java-lang-3/pom.xml‎

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<assertj.version>3.12.2</assertj.version>
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</properties>
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</project>
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</project>

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

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

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

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

‎patterns/hexagonal-architecture/pom.xml‎

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-parent</artifactId>
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<version>2.3.0.RELEASE</version>
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<relativePath/> <!-- lookup parent from repository -->
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</parent>
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<groupId>com.baeldung</groupId>
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<artifactId>hexagonal-architecture</artifactId>
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<version>1.0</version>
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<name>hexagonal-architecture</name>
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<description>Project for hexagonal architecture in java</description>
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<properties>
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<java.version>1.8</java.version>
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</properties>
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<dependencies>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-web</artifactId>
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</dependency>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-data-mongodb</artifactId>
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</dependency>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-test</artifactId>
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<scope>test</scope>
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<exclusions>
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<exclusion>
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<groupId>org.junit.vintage</groupId>
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<artifactId>junit-vintage-engine</artifactId>
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</exclusion>
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</exclusions>
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</dependency>
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<dependency>
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<groupId>org.mockito</groupId>
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<artifactId>mockito-core</artifactId>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<build>
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<plugins>
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<plugin>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-maven-plugin</artifactId>
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</plugin>
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</plugins>
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</build>
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</project>

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

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

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

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

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

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

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

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

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

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

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

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package com.baeldung.pattern.hexagonal.domain.services;
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import com.baeldung.pattern.hexagonal.domain.model.Employee;
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public interface EmployeeService {
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Employee addEmployee(Employee employee);
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Employee getEmployee(String employeeId);
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}

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