BAEL-7615 - Implement the Builder Pattern in Java 8 (#16399)

* BAEL-7255 - Implementing GraphQL Mutation without Returning Data

* BAEL-7615 - Implement the Builder Pattern in Java 8

* BAEL-7615 - Implement the Builder Pattern in Java 8

patterns-modules/design-patterns-creational-2/pom.xml

@@ -19,10 +19,15 @@
             <version>${mockito-inline.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.32</version>
+        </dependency>
     </dependencies>
 
     <properties>
         <mockito-inline.version>5.2.0</mockito-inline.version>
     </properties>
 
-</project>
+</project>

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/implementation/GenericBuilder.java

@@ -0,0 +1,29 @@
+package com.baeldung.builder.implementation;
+
+import java.util.function.BiConsumer;
+import java.util.function.Supplier;
+
+public class GenericBuilder<T> {
+
+    private final Supplier<T> supplier;
+
+    private GenericBuilder(Supplier<T> supplier) {
+        this.supplier = supplier;
+    }
+
+    public static <T> GenericBuilder<T> of(Supplier<T> supplier) {
+        return new GenericBuilder<>(supplier);
+    }
+
+    public <P> GenericBuilder<T> with(BiConsumer<T, P> consumer, P value) {
+        return new GenericBuilder<>(() -> {
+            T object = supplier.get();
+            consumer.accept(object, value);
+            return object;
+        });
+    }
+
+    public T build() {
+        return supplier.get();
+    }
+}

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/implementation/LombokPost.java

@@ -0,0 +1,18 @@
+package com.baeldung.builder.implementation;
+
+import lombok.Builder;
+import lombok.Getter;
+import lombok.Setter;
+
+@Builder
+@Getter
+@Setter
+public class LombokPost {
+
+    private String title;
+
+    private String text;
+
+    private String category;
+
+}

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/implementation/Post.java

@@ -0,0 +1,74 @@
+package com.baeldung.builder.implementation;
+
+public class Post {
+
+    private String title;
+
+    private String text;
+
+    private String category;
+
+    Post(Builder builder) {
+        this.title = builder.title;
+        this.text = builder.text;
+        this.category = builder.category;
+    }
+
+    Post() {}
+
+    public String getTitle() {
+        return title;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public String getCategory() {
+        return category;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    public void setCategory(String category) {
+        this.category = category;
+    }
+
+    @Override
+    public String toString() {
+        return "Post{" + "title='" + title + '\'' + ", text='" + text + '\'' + ", category='" + category + '\'' + '}';
+    }
+
+    public static class Builder {
+        private String title;
+        private String text;
+        private String category;
+
+        public Builder() {}
+
+        public Builder title(String title) {
+            this.title = title;
+            return this;
+        }
+
+        public Builder text(String text) {
+            this.text = text;
+            return this;
+        }
+
+        public Builder category(String category) {
+            this.category = category;
+            return this;
+        }
+
+        public Post build() {
+            return new Post(this);
+        }
+    }
+}

patterns-modules/design-patterns-creational-2/src/test/java/com/baeldung/builder/implementation/BuilderImplementationUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.builder.implementation;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class BuilderImplementationUnitTest {
+
+    @Test
+    void givenClassicBuilder_whenBuild_thenReturnObject() {
+
+        Post post = new Post.Builder()
+          .title("Java Builder Pattern")
+          .text("Explaining how to implement the Builder Pattern in Java")
+          .category("Programming")
+          .build();
+
+        assertEquals("Java Builder Pattern", post.getTitle());
+        assertEquals("Explaining how to implement the Builder Pattern in Java", post.getText());
+        assertEquals("Programming", post.getCategory());
+    }
+
+    @Test
+    void givenGenericBuilder_whenBuild_thenReturnObject() {
+
+        Post post = GenericBuilder.of(Post::new)
+          .with(Post::setTitle, "Java Builder Pattern")
+          .with(Post::setText, "Explaining how to implement the Builder Pattern in Java")
+          .with(Post::setCategory, "Programming")
+          .build();
+
+        assertEquals("Java Builder Pattern", post.getTitle());
+        assertEquals("Explaining how to implement the Builder Pattern in Java", post.getText());
+        assertEquals("Programming", post.getCategory());
+    }
+
+    @Test
+    void givenLombokBuilder_whenBuild_thenReturnObject() {
+
+        LombokPost post = LombokPost.builder()
+          .title("Java Builder Pattern")
+          .text("Explaining how to implement the Builder Pattern in Java")
+          .category("Programming")
+          .build();
+
+        assertEquals("Java Builder Pattern", post.getTitle());
+        assertEquals("Explaining how to implement the Builder Pattern in Java", post.getText());
+        assertEquals("Programming", post.getCategory());
+    }
+}