Add design pattern project with step builder pattern

design-pattern/README.md

@@ -0,0 +1 @@
+# Related articles

design-pattern/pom.xml

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+<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/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.geekyhacker.design-pattern</groupId>
+  <artifactId>geeky-hacker-design-pattern</artifactId>
+  <packaging>jar</packaging>
+  <version>1.0-SNAPSHOT</version>
+  <name>geeky-hacker-design-pattern</name>
+  <url>https://geekyhacker.com</url>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <java.version>21</java.version>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.apache.commons</groupId>
+      <artifactId>commons-lang3</artifactId>
+      <version>3.14.0</version>
+    </dependency>
+
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-api</artifactId>
+      <version>5.10.2</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-params</artifactId>
+      <version>5.10.2</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-core</artifactId>
+      <version>5.11.0</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-junit-jupiter</artifactId>
+      <version>5.11.0</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-compiler-plugin</artifactId>
+          <version>3.13.0</version>
+          <configuration>
+            <source>21</source>
+            <target>21</target>
+          </configuration>
+        </plugin>
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-surefire-plugin</artifactId>
+          <version>3.2.5</version>
+        </plugin>
+    </plugins>
+  </build>
+</project>

design-pattern/src/main/java/com/geekyhacker/design/pattern/creational/DatabaseConnector.java

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+package com.geekyhacker.design.pattern.creational;
+
+public class DatabaseConnector {
+  private final String username;
+  private final String password;
+  private final String url;
+  private final int port;
+
+  DatabaseConnector(String username, String password, String url, int port) {
+    this.username = username;
+    this.password = password;
+    this.url = url;
+    this.port = port;
+  }
+
+  public String getUsername() {
+    return username;
+  }
+
+  public String getPassword() {
+    return password;
+  }
+
+  public String getUrl() {
+    return url;
+  }
+
+  public int getPort() {
+    return port;
+  }
+
+  public boolean connect() {
+    System.out.println("Connecting to the database");
+    return true;
+  }
+}

design-pattern/src/main/java/com/geekyhacker/design/pattern/creational/DatabaseConnectorBuilder.java

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+package com.geekyhacker.design.pattern.creational;
+
+public class DatabaseConnectorBuilder {
+  private String username;
+  private String password;
+  private String url;
+  private int port;
+
+  public static DatabaseConnectorBuilder newBuilder() {
+    return new DatabaseConnectorBuilder();
+  }
+
+  public DatabaseConnectorBuilder withUsername(String username) {
+    this.username = username;
+    return this;
+  }
+
+  public DatabaseConnectorBuilder withPassword(String password) {
+    this.password = password;
+    return this;
+  }
+
+  public DatabaseConnectorBuilder withUrl(String url) {
+    this.url = url;
+    return this;
+  }
+
+  public DatabaseConnectorBuilder withPort(int port) {
+    this.port = port;
+    return this;
+  }
+
+  public DatabaseConnector build() {
+    return new DatabaseConnector(username, password, url, port);
+  }
+}

design-pattern/src/main/java/com/geekyhacker/design/pattern/creational/DatabaseConnectorStepBuilder.java

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+package com.geekyhacker.design.pattern.creational;
+
+public class DatabaseConnectorStepBuilder {
+  private DatabaseConnectorStepBuilder() {
+  }
+
+  public static UsernameBuilder newBuilder() {
+    return new Builder();
+  }
+
+  public interface UsernameBuilder {
+    PasswordBuilder withUsername(String username);
+  }
+
+  public interface PasswordBuilder {
+    UrlBuilder withPassword(String password);
+  }
+
+  public interface UrlBuilder {
+    PortBuilder withUrl(String url);
+  }
+
+  public interface PortBuilder {
+    BuildStep withPort(int port);
+  }
+
+  public interface BuildStep {
+    DatabaseConnector build();
+  }
+
+  private static class Builder implements UsernameBuilder, PasswordBuilder, UrlBuilder, PortBuilder, BuildStep {
+    private String username;
+    private String password;
+    private String url;
+    private int port;
+
+    private Builder() {
+
+    }
+
+    @Override
+    public PasswordBuilder withUsername(String username) {
+      this.username = username;
+      return this;
+    }
+
+    @Override
+    public UrlBuilder withPassword(String password) {
+      this.password = password;
+      return this;
+    }
+
+    @Override
+    public PortBuilder withUrl(String url) {
+      this.url = url;
+      return this;
+    }
+
+    @Override
+    public BuildStep withPort(int port) {
+      this.port = port;
+      return this;
+    }
+
+    @Override
+    public DatabaseConnector build() {
+      return new DatabaseConnector(username, password, url, port);
+    }
+  }
+}

design-pattern/src/test/java/com/geekyhacker/design/pattern/creational/DatabaseConnectorBuilderTest.java

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+package com.geekyhacker.design.pattern.creational;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+public class DatabaseConnectorBuilderTest {
+
+  @Test
+  void shouldBuildDatabaseConnectorFully() {
+    DatabaseConnector connector = DatabaseConnectorBuilder.newBuilder()
+        .withUsername("root")
+        .withPassword("secret")
+        .withUrl("localhost")
+        .withPort(3306)
+        .build();
+
+    assertEquals("root", connector.getUsername());
+    assertEquals("secret", connector.getPassword());
+    assertEquals("localhost", connector.getUrl());
+    assertEquals(3306, connector.getPort());
+  }
+
+  @Test
+  void shouldBuildDatabaseConnectorWithoutUrl() {
+    DatabaseConnector connector = DatabaseConnectorBuilder.newBuilder()
+        .withUsername("root")
+        .withPassword("secret")
+        .withPort(3306)
+        .build();
+
+    assertEquals("root", connector.getUsername());
+    assertEquals("secret", connector.getPassword());
+    assertEquals(3306, connector.getPort());
+    assertNull(connector.getUrl());
+  }
+
+  @Test
+  void shouldBuildDatabaseConnectorWithoutAnyParameter() {
+    DatabaseConnector connector = DatabaseConnectorBuilder.newBuilder().build();
+
+    assertNull(connector.getUsername());
+    assertNull(connector.getPassword());
+    assertNull(connector.getUrl());
+    assertEquals(0, connector.getPort());
+  }
+}

design-pattern/src/test/java/com/geekyhacker/design/pattern/creational/DatabaseConnectorStepBuilderTest.java

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+package com.geekyhacker.design.pattern.creational;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class DatabaseConnectorStepBuilderTest {
+
+  @Test
+  void shouldBuildDatabaseConnector() {
+    DatabaseConnector connector = DatabaseConnectorStepBuilder.newBuilder()
+        .withUsername("root")
+        .withPassword("secret")
+        .withUrl("localhost")
+        .withPort(3306)
+        .build();
+
+    assertEquals("root", connector.getUsername());
+    assertEquals("secret", connector.getPassword());
+    assertEquals("localhost", connector.getUrl());
+    assertEquals(3306, connector.getPort());
+  }
+}

pom.xml

@@ -14,5 +14,6 @@
     <module>cryptography</module>
     <module>jdbc</module>
     <module>spring-boot</module>
+    <module>design-pattern</module>
   </modules>
 </project>