feat(hw-03): implement Strategy pattern

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

@@ -8,6 +8,7 @@ import org.example.builder.*;
 import org.example.chain.*;
 import org.example.decorator.*;
 import org.example.proxy.*;
+import org.example.strategy.*;
 
 public class App {
   public static void main(String[] args) {
@@ -16,10 +17,16 @@ public class App {
 
   private static void run() {
     checkAdapterPattern();
+
     checkBuilderPattern();
+
     checkChainPattern();
+
     checkDecoratorPattern();
+
     checkProxyPattern();
+
+    checkStrategyPattern();
   }
 
   private static void checkAdapterPattern() {
@@ -57,4 +64,16 @@ public class App {
 
     proxy.execute();
   }
+
+  private static void checkStrategyPattern() {
+    Context context = new Context(new ConcreteStrategyA());
+
+    boolean crayfishWhistled = true; // Если рак на горе свистнул
+
+    if (crayfishWhistled) {
+      context.setStrategy(new ConcreteStrategyB());
+    }
+
+    context.executeStrategy();
+  }
 }

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

@@ -0,0 +1,10 @@
+package org.example.strategy;
+
+/** Concrete Strategy A */
+public class ConcreteStrategyA implements Strategy {
+
+  @Override
+  public void execute() {
+    System.out.println("ConcreteStrategyA выполняет операцию");
+  }
+}

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

@@ -0,0 +1,10 @@
+package org.example.strategy;
+
+/** Concrete Strategy B */
+public class ConcreteStrategyB implements Strategy {
+
+  @Override
+  public void execute() {
+    System.out.println("ConcreteStrategyB выполняет операцию");
+  }
+}

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

@@ -0,0 +1,19 @@
+package org.example.strategy;
+
+/** Context */
+public class Context {
+
+  public Context(Strategy strategy) {
+    this.strategy = strategy;
+  }
+
+  public void setStrategy(Strategy strategy) {
+    this.strategy = strategy;
+  }
+
+  public void executeStrategy() {
+    strategy.execute();
+  }
+
+  private Strategy strategy;
+}

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

@@ -0,0 +1,6 @@
+package org.example.strategy;
+
+/** Strategy */
+public interface Strategy {
+  void execute();
+}