feat(hw-03): implement Decorator pattern

hw-03/project-root/app/src/main/java/org/example/App.java

@@ -6,6 +6,7 @@ package org.example;
 import org.example.adapter.*;
 import org.example.builder.*;
 import org.example.chain.*;
+import org.example.decorator.*;
 
 public class App {
   public static void main(String[] args) {
@@ -16,6 +17,7 @@ public class App {
     checkAdapterPattern();
     checkBuilderPattern();
     checkChainPattern();
+    checkDecoratorPattern();
   }
 
   private static void checkAdapterPattern() {
@@ -39,4 +41,11 @@ public class App {
     handler.handle(42);
     handler.handle("Hello");
   }
+
+  private static void checkDecoratorPattern() {
+    Component component = new ConcreteComponent();
+    Component decorator = new ConcreteDecorator(component);
+
+    decorator.operation();
+  }
 }

hw-03/project-root/app/src/main/java/org/example/decorator/Component.java

@@ -0,0 +1,6 @@
+package org.example.decorator;
+
+/** Component */
+public interface Component {
+  void operation();
+}

hw-03/project-root/app/src/main/java/org/example/decorator/ConcreteComponent.java

@@ -0,0 +1,10 @@
+package org.example.decorator;
+
+/** Concrete Component */
+public class ConcreteComponent implements Component {
+
+  @Override
+  public void operation() {
+    System.out.println("ConcreteComponent выполняет операцию");
+  }
+}

hw-03/project-root/app/src/main/java/org/example/decorator/ConcreteDecorator.java

@@ -0,0 +1,15 @@
+package org.example.decorator;
+
+/** Concrete Decorator */
+public class ConcreteDecorator extends Decorator {
+
+  public ConcreteDecorator(Component component) {
+    super(component);
+  }
+
+  @Override
+  public void operation() {
+    component.operation();
+    System.out.println("ConcreteDecorator добавляет поведение");
+  }
+}

hw-03/project-root/app/src/main/java/org/example/decorator/Decorator.java

@@ -0,0 +1,16 @@
+package org.example.decorator;
+
+/** Decorator */
+public abstract class Decorator implements Component {
+
+  protected Decorator(Component component) {
+    this.component = component;
+  }
+
+  @Override
+  public void operation() {
+    component.operation();
+  }
+
+  protected final Component component;
+}