### Complete Example Execution

Source: https://github.com/iluwatar/java-design-patterns/blob/master/business-delegate/README.md

This main method demonstrates the setup and execution of the Business Delegate pattern, showing how the client interacts with the delegate to play different movies.

```java
public static void main(String[] args) {

    // prepare the objects
    var businessDelegate = new BusinessDelegate();
    var businessLookup = new BusinessLookup();
    businessLookup.setNetflixService(new NetflixService());
    businessLookup.setYouTubeService(new YouTubeService());
    businessDelegate.setLookupService(businessLookup);

    // create the client and use the business delegate
    var client = new MobileClient(businessDelegate);
    client.playbackMovie("Die Hard 2");
    client.playbackMovie("Maradona: The Greatest Ever");
}
```

--------------------------------

### Java Server Session Application Setup

Source: https://github.com/iluwatar/java-design-patterns/blob/master/server-session/README.md

Sets up an HTTP server with contexts for login and logout, and starts a background task for session expiration. Ensure the server port is available.

```java
public class App {

  private static Map<String, Integer> sessions = new HashMap<>();
  private static Map<String, Instant> sessionCreationTimes = new HashMap<>();
  private static final long SESSION_EXPIRATION_TIME = 10000;

  public static void main(String[] args) throws IOException {
    HttpServer server = HttpServer.create(new InetSocketAddress(8080), 0);

    server.createContext("/login", new LoginHandler(sessions, sessionCreationTimes));
    server.createContext("/logout", new LogoutHandler(sessions, sessionCreationTimes));

    server.start();

    sessionExpirationTask();
  }

  private static void sessionExpirationTask() {
    new Thread(() -> {
      while (true) {
        try {
          Thread.sleep(SESSION_EXPIRATION_TIME);
          Instant currentTime = Instant.now();
          synchronized (sessions) {
            synchronized (sessionCreationTimes) {
              Iterator<Map.Entry<String, Instant>> iterator = 
                  sessionCreationTimes.entrySet().iterator();
              while (iterator.hasNext()) {
                Map.Entry<String, Instant> entry = iterator.next();
                if (entry.getValue().plusMillis(SESSION_EXPIRATION_TIME).isBefore(currentTime)) {
                  sessions.remove(entry.getKey());
                  iterator.remove();
                }
              }
            }
          }
        } catch (InterruptedException e) {
          Thread.currentThread().interrupt();
        }
      }
    }).start();
  }
}
```

--------------------------------

### Java Reactor Pattern Application Setup

Source: https://github.com/iluwatar/java-design-patterns/blob/master/reactor/README.md

This Java code demonstrates the setup of an application using the Reactor pattern. It initializes a dispatcher, reactor, handler, and registers channels before starting the reactor to handle events.

```java
}
}
```
```

--------------------------------

### Console Output Example

Source: https://github.com/iluwatar/java-design-patterns/blob/master/queue-based-load-leveling/README.md

Illustrates the typical console output when running the Queue-Based Load Leveling pattern example, showing task submission and service.

```text
[main] INFO App - Submitting TaskGenerators and ServiceExecutor threads.
[main] INFO App - Initiating shutdown. Executor will shutdown only after all the Threads are completed.
[pool-1-thread-2] INFO TaskGenerator - Message-1 submitted by pool-1-thread-2
[pool-1-thread-1] INFO TaskGenerator - Message-5 submitted by pool-1-thread-1
[pool-1-thread-1] INFO TaskGenerator - Message-4 submitted by pool-1-thread-1
[pool-1-thread-2] INFO TaskGenerator - Message-2 submitted by pool-1-thread-2
[pool-1-thread-1] INFO TaskGenerator - Message-3 submitted by pool-1-thread-1
[pool-1-thread-2] INFO TaskGenerator - Message-1 submitted by pool-1-thread-2
[pool-1-thread-1] INFO TaskGenerator - Message-2 submitted by pool-1-thread-1
[pool-1-thread-2] INFO ServiceExecutor - Message-1 submitted by pool-1-thread-2 is served.
[pool-1-thread-1] INFO TaskGenerator - Message-1 submitted by pool-1-thread-1
[pool-1-thread-2] INFO ServiceExecutor - Message-5 submitted by pool-1-thread-1 is served.
[pool-1-thread-2] INFO ServiceExecutor - Message-4 submitted by pool-1-thread-1 is served.
[pool-1-thread-2] INFO ServiceExecutor - Message-2 submitted by pool-1-thread-2 is served.
[pool-1-thread-2] INFO ServiceExecutor - Message-3 submitted by pool-1-thread-1 is served.
[pool-1-thread-2] INFO ServiceExecutor - Message-1 submitted by pool-1-thread-2 is served.
[pool-1-thread-2] INFO ServiceExecutor - Message-2 submitted by pool-1-thread-1 is served.
[pool-1-thread-2] INFO ServiceExecutor - Message-1 submitted by pool-1-thread-1 is served.
[pool-1-thread-2] INFO ServiceExecutor - Service Executor: Waiting for Messages to serve .. 

```

--------------------------------

### Example Actor System Usage in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/actor-model/README.md

Demonstrates starting two actors, sending messages between them, and then gracefully stopping them and the system. Includes a delay to allow message processing.

```java
public class App {
  public static void main(String[] args) {
    ActorSystem system = new ActorSystem();
      Actor srijan = new ExampleActor(system);
      Actor ansh = new ExampleActor2(system);

      system.startActor(srijan);
      system.startActor(ansh);
      ansh.send(new Message("Hello ansh", srijan.getActorId()));
      srijan.send(new Message("Hello srijan!", ansh.getActorId()));

      Thread.sleep(1000); // Give time for messages to process

      srijan.stop(); // Stop the actor gracefully
      ansh.stop();
      system.shutdown(); // Stop the actor system
  }
}
```

--------------------------------

### Example Character Creation

Source: https://github.com/iluwatar/java-design-patterns/blob/master/step-builder/README.md

Demonstrates the guided, step-by-step construction of different character types (warrior, mage, thief) using the Step Builder pattern.

```java
public static void main(String[] args) {

    var warrior = CharacterStepBuilder
            .newBuilder()
            .name("Amberjill")
            .fighterClass("Paladin")
            .withWeapon("Sword")
            .noAbilities()
            .build();

    LOGGER.info(warrior.toString());

    var mage = CharacterStepBuilder
            .newBuilder()
            .name("Riobard")
            .wizardClass("Sorcerer")
            .withSpell("Fireball")
            .withAbility("Fire Aura")
            .withAbility("Teleport")
            .noMoreAbilities()
            .build();

    LOGGER.info(mage.toString());

    var thief = CharacterStepBuilder
            .newBuilder()
            .name("Desmond")
            .fighterClass("Rogue")
            .noWeapon()
            .build();

    LOGGER.info(thief.toString());
}
```

--------------------------------

### Console Output Example

Source: https://github.com/iluwatar/java-design-patterns/blob/master/business-delegate/README.md

The expected console output when the complete example is executed, showing which services processed the movie requests.

```text
21:15:33.790 [main] INFO com.iluwatar.business.delegate.NetflixService - NetflixService is now processing
21:15:33.794 [main] INFO com.iluwatar.business.delegate.YouTubeService - YouTubeService is now processing
```

--------------------------------

### Service Locator Pattern Example Output in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/service-locator/README.md

Shows the expected log output when running the Service Locator pattern example. It illustrates service lookup, creation, execution, and caching.

```text
15:39:51.417 [main] INFO com.iluwatar.servicelocator.InitContext -- Looking up service A and creating new service for A
15:39:51.419 [main] INFO com.iluwatar.servicelocator.ServiceImpl -- Service jndi/serviceA is now executing with id 56
15:39:51.420 [main] INFO com.iluwatar.servicelocator.InitContext -- Looking up service B and creating new service for B
15:39:51.420 [main] INFO com.iluwatar.servicelocator.ServiceImpl -- Service jndi/serviceB is now executing with id 196
15:39:51.420 [main] INFO com.iluwatar.servicelocator.ServiceCache -- (cache call) Fetched service jndi/serviceA(56) from cache... !
15:39:51.420 [main] INFO com.iluwatar.servicelocator.ServiceImpl -- Service jndi/serviceA is now executing with id 56
15:39:51.420 [main] INFO com.iluwatar.servicelocator.ServiceCache -- (cache call) Fetched service jndi/serviceA(56) from cache... !
15:39:51.420 [main] INFO com.iluwatar.servicelocator.ServiceImpl -- Service jndi/serviceA is now executing with id 56
```

--------------------------------

### Example Frontend Components in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/microservices-client-side-ui-composition/README.md

Provides example implementations of the FrontendComponent interface for 'Product' and 'Cart' modules. These components define how to fetch data specific to their domain.

```java
public class ProductComponent implements FrontendComponent {
    @Override
    public String fetchData(Map<String, String> params) {
        return "Displaying Products: " + params.getOrDefault("category", "all");
    }
}

public class CartComponent implements FrontendComponent {
    @Override
    public String fetchData(Map<String, String> params) {
        return "Displaying Cart for User: " + params.getOrDefault("userId", "unknown");
    }
}
```

--------------------------------

### Example Output of Clean Architecture Simulation

Source: https://github.com/iluwatar/java-design-patterns/blob/master/clean-architecture/README.md

This markdown block shows the expected output from the Java programmatic example, detailing the calculated total and the confirmation of a placed order.

```markdown
Total: $2000.0
Order placed! Order ID: ORDER-1743349969254, Total: $2000.0
```

--------------------------------

### Program Output Example

Source: https://github.com/iluwatar/java-design-patterns/blob/master/producer-consumer/README.md

Illustrates the typical log output from the consumer threads as they process items from the queue.

```text
08:10:08.008 [pool-1-thread-3] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_0] consume item [0] produced by [Producer_1]
08:10:08.008 [pool-1-thread-4] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_1] consume item [0] produced by [Producer_0]
08:10:08.517 [pool-1-thread-5] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_2] consume item [1] produced by [Producer_0]
08:10:08.952 [pool-1-thread-3] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_0] consume item [1] produced by [Producer_1]
08:10:09.208 [pool-1-thread-4] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_1] consume item [2] produced by [Producer_0]
08:10:09.354 [pool-1-thread-5] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_2] consume item [2] produced by [Producer_1]
08:10:10.214 [pool-1-thread-3] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_0] consume item [3] produced by [Producer_1]
08:10:10.585 [pool-1-thread-4] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_1] consume item [3] produced by [Producer_0]
08:10:11.530 [pool-1-thread-5] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_2] consume item [4] produced by [Producer_1]
08:10:11.682 [pool-1-thread-3] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_0] consume item [4] produced by [Producer_0]
08:10:11.781 [pool-1-thread-4] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_1] consume item [5] produced by [Producer_0]
08:10:12.209 [pool-1-thread-5] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_2] consume item [5] produced by [Producer_1]
08:10:13.045 [pool-1-thread-3] INFO com.iluwatar.producer.consumer.Consumer -- Consumer [Consumer_0] consume item [6] produced by [Producer_0]
```

--------------------------------

### Application Entry Point: App Class

Source: https://github.com/iluwatar/java-design-patterns/blob/master/model-view-presenter/README.md

Wires together the Model, View, and Presenter components to initialize and start the application.

```java
public class App {
  public static void main(String[] args) {
    var loader = new FileLoader();
    var frame = new FileSelectorJFrame();
    var presenter = new FileSelectorPresenter(frame);
    presenter.setLoader(loader);
    presenter.start();
  }
}
```

--------------------------------

### Application Setup with Jersey

Source: https://github.com/iluwatar/java-design-patterns/blob/master/partial-response/README.md

Initializes the web server using Jersey and registers the VideoResource. The server listens on http://localhost:8080/.

```java
public class App {
    public static void main(String[] args) {
        ResourceConfig config = new ResourceConfig();
        config.register(VideoResource.class);
        SimpleContainerFactory.create("http://localhost:8080/", config);
    }
}
```

--------------------------------

### Main Application Setup and Execution

Source: https://github.com/iluwatar/java-design-patterns/blob/master/unit-of-work/README.md

Sets up the Weapon entities, initializes the ArmsDealer repository, performs operations, and commits them. This demonstrates the practical usage of the Unit of Work pattern.

```java
import java.util.HashMap;

public class Main {

    public static void main(String[] args) {
        // create some weapons
        var enchantedHammer = new Weapon(1, "enchanted hammer");
        var brokenGreatSword = new Weapon(2, "broken great sword");
        var silverTrident = new Weapon(3, "silver trident");

        // create repository
        var weaponRepository = new ArmsDealer(new HashMap<>(),
                new WeaponDatabase());

        // perform operations on the weapons
        weaponRepository.registerNew(enchantedHammer);
        weaponRepository.registerModified(silverTrident);
        weaponRepository.registerDeleted(brokenGreatSword);
        weaponRepository.commit();
    }
}
```

--------------------------------

### Demonstrate Dependency Injection Usage in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/dependency-injection/README.md

Shows how to instantiate and use `SimpleWizard`, `AdvancedWizard`, `AdvancedSorceress`, and a `GuiceWizard` with different tobacco dependencies. Includes setup for Guice DI.

```java
public static void main(String[] args) {
    var simpleWizard = new SimpleWizard();
    simpleWizard.smoke();

    var advancedWizard = new AdvancedWizard(new SecondBreakfastTobacco());
    advancedWizard.smoke();

    var advancedSorceress = new AdvancedSorceress();
    advancedSorceress.setTobacco(new SecondBreakfastTobacco());
    advancedSorceress.smoke();

    var injector = Guice.createInjector(new TobaccoModule());
    var guiceWizard = injector.getInstance(GuiceWizard.class);
    guiceWizard.smoke();
}
```

--------------------------------

### Reactor Pattern Output Log

Source: https://github.com/iluwatar/java-design-patterns/blob/master/reactor/README.md

This is the expected output log when running the Reactor Pattern example. It shows the binding of TCP and UDP sockets and the reactor starting to wait for events.

```log
09:50:08.317 [main] INFO com.iluwatar.reactor.framework.NioServerSocketChannel -- Bound TCP socket at port: 16666
09:50:08.320 [main] INFO com.iluwatar.reactor.framework.NioServerSocketChannel -- Bound TCP socket at port: 16667
09:50:08.323 [main] INFO com.iluwatar.reactor.framework.NioDatagramChannel -- Bound UDP socket at port: 16668
09:50:08.324 [main] INFO com.iluwatar.reactor.framework.NioDatagramChannel -- Bound UDP socket at port: 16669
09:50:08.324 [pool-2-thread-1] INFO com.iluwatar.reactor.framework.NioReactor -- Reactor started, waiting for events...
```

--------------------------------

### Main Example Execution

Source: https://github.com/iluwatar/java-design-patterns/blob/master/command/README.md

Demonstrates the Command pattern by having a Wizard cast spells on a Goblin, then undoing and redoing them. This showcases the full lifecycle of command execution and state changes.

```java
public static void main(String[] args) {
    var wizard = new Wizard();
    var goblin = new Goblin();

    goblin.printStatus();

    wizard.castSpell(goblin::changeSize);
    goblin.printStatus();

    wizard.castSpell(goblin::changeVisibility);
    goblin.printStatus();

    wizard.undoLastSpell();
    goblin.printStatus();

    wizard.undoLastSpell();
    goblin.printStatus();

    wizard.redoLastSpell();
    goblin.printStatus();

    wizard.redoLastSpell();
    goblin.printStatus();
}
```

--------------------------------

### Demonstrate Data Bus Pattern in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/data-bus/README.md

Sets up the Data Bus, subscribes different member types, and publishes a StartingData event to show selective message handling.

```java
class App {

    public static void main(String[] args) {
        final var bus = DataBus.getInstance();
        bus.subscribe(new StatusMember(1));
        bus.subscribe(new StatusMember(2));
        final var foo = new MessageCollectorMember("Foo");
        final var bar = new MessageCollectorMember("Bar");
        bus.subscribe(foo);
        bus.publish(StartingData.of(LocalDateTime.now()));
    }
}
```

--------------------------------

### Console Output of RAII Example (Java)

Source: https://github.com/iluwatar/java-design-patterns/blob/master/resource-acquisition-is-initialization/README.md

The expected console output when running the RAII example with SlidingDoor and TreasureChest.

```text
10:07:14.833 [main] INFO com.iluwatar.resource.acquisition.is.initialization.SlidingDoor -- Sliding door opens.
10:07:14.835 [main] INFO com.iluwatar.resource.acquisition.is.initialization.App -- Walking in.
10:07:14.835 [main] INFO com.iluwatar.resource.acquisition.is.initialization.SlidingDoor -- Sliding door closes.
10:07:14.835 [main] INFO com.iluwatar.resource.acquisition.is.initialization.TreasureChest -- Treasure chest opens.
10:07:14.835 [main] INFO com.iluwatar.resource.acquisition.is.initialization.App -- Looting contents.
10:07:14.835 [main] INFO com.iluwatar.resource.acquisition.is.initialization.TreasureChest -- Treasure chest closes.
```

--------------------------------

### Main Method for Virtual Machine Execution

Source: https://github.com/iluwatar/java-design-patterns/blob/master/bytecode/README.md

This is the main entry point for the program, demonstrating how to initialize and use the VirtualMachine. It executes a sequence of instructions converted to bytecode, simulating a series of operations on wizard attributes.

```java
public static void main(String[] args) {

    var vm = new VirtualMachine(
            new Wizard(45, 7, 11, 0, 0),
            new Wizard(36, 18, 8, 0, 0));

    vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0));
    vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0));
    vm.execute(InstructionConverterUtil.convertToByteCode(String.format(HEALTH_PATTERN, "GET")));
    vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0));
    vm.execute(InstructionConverterUtil.convertToByteCode(GET_AGILITY));
    vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0));
    vm.execute(InstructionConverterUtil.convertToByteCode(GET_WISDOM));
    vm.execute(InstructionConverterUtil.convertToByteCode(ADD));
    vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_2));
    vm.execute(InstructionConverterUtil.convertToByteCode(DIVIDE));
    vm.execute(InstructionConverterUtil.convertToByteCode(ADD));
    vm.execute(InstructionConverterUtil.convertToByteCode(String.format(HEALTH_PATTERN, "SET")));
}
```

--------------------------------

### Demonstrate Role Object Pattern Usage

Source: https://github.com/iluwatar/java-design-patterns/blob/master/role-object/README.md

Example of creating a customer with multiple roles, checking for roles, and invoking role-specific methods.

```java
public static void main(String[] args) {
    var customer = Customer.newCustomer(BORROWER, INVESTOR);

    LOGGER.info("New customer created : {}", customer);

    var hasBorrowerRole = customer.hasRole(BORROWER);
    LOGGER.info("Customer has a borrower role - {}", hasBorrowerRole);
    var hasInvestorRole = customer.hasRole(INVESTOR);
    LOGGER.info("Customer has an investor role - {}", hasInvestorRole);

    customer.getRole(INVESTOR, InvestorRole.class)
            .ifPresent(inv -> {
                inv.setAmountToInvest(1000);
                inv.setName("Billy");
            });
    customer.getRole(BORROWER, BorrowerRole.class)
            .ifPresent(inv -> inv.setName("Johny"));

    customer.getRole(INVESTOR, InvestorRole.class)
            .map(InvestorRole::invest)
            .ifPresent(LOGGER::info);

    customer.getRole(BORROWER, BorrowerRole.class)
            .map(BorrowerRole::borrow)
            .ifPresent(LOGGER::info);
}
```

--------------------------------

### Example Output

Source: https://github.com/iluwatar/java-design-patterns/blob/master/ambassador/README.md

Illustrates the expected output when running the Ambassador Pattern example, showing latency, retries, and final results.

```text
Time taken(ms):111
Service result:120
Time taken(ms):931
Failed to reach remote:(1)
Time taken(ms):665
Failed to reach remote:(2)
Time taken(ms):538
Failed to reach remote:(3)
Service result:-1
```

--------------------------------

### Start Asynchronous Event in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/event-based-asynchronous/README.md

Illustrates how an `AsyncEvent` is started in a separate thread. This prevents the main thread from being blocked during event execution.

```java
@Override
public void start() {
  Thread thread = new Thread(() -> {
    try {
      handleRunStart();
      Thread.sleep(getRuntime().toMillis());
      handleRunComplete();
    } catch (InterruptedException e) {
      handleRunFailure(e.getMessage());
    }
  });
  thread.start();
}
```

--------------------------------

### App Class: Entry Point for MVI Example

Source: https://github.com/iluwatar/java-design-patterns/blob/master/model-view-intent/README.md

Serves as the application's entry point, initializing the View and ViewModel, and simulating user interactions with the calculator.

```java
public final class App {
  private static final double RANDOM_VARIABLE = 10.0;

  public static void main(final String[] args) {
    var view = new CalculatorView(new CalculatorViewModel());
    var variable1 = RANDOM_VARIABLE;

    view.setVariable(variable1);
    view.add();
    view.displayTotal();

    variable1 = 2.0;
    view.setVariable(variable1);
    view.subtract();
    view.divide();
    view.multiply();
    view.displayTotal();
  }

  private App() {
  }
}
```

--------------------------------

### Console Output of Strangler Pattern Example

Source: https://github.com/iluwatar/java-design-patterns/blob/master/strangler/README.md

Shows the log output generated during the execution of the Strangler pattern example, illustrating the behavior of each system stage.

```log
13:02:25.030 [main] INFO com.iluwatar.strangler.OldArithmetic -- Arithmetic sum 1.0
13:02:25.032 [main] INFO com.iluwatar.strangler.OldSource -- Source module 1.0
13:02:25.032 [main] INFO com.iluwatar.strangler.OldArithmetic -- Arithmetic mul 1.0
13:02:25.032 [main] INFO com.iluwatar.strangler.OldSource -- Source module 1.0
13:02:25.032 [main] INFO com.iluwatar.strangler.HalfArithmetic -- Arithmetic sum 1.5
13:02:25.032 [main] INFO com.iluwatar.strangler.HalfSource -- Source module 1.5
13:02:25.033 [main] INFO com.iluwatar.strangler.HalfArithmetic -- Arithmetic mul 1.5
13:02:25.033 [main] INFO com.iluwatar.strangler.OldSource -- Source module 1.0
13:02:25.033 [main] INFO com.iluwatar.strangler.HalfArithmetic -- Arithmetic check zero 1.5
13:02:25.033 [main] INFO com.iluwatar.strangler.HalfSource -- Source module 1.5
13:02:25.034 [main] INFO com.iluwatar.strangler.NewArithmetic -- Arithmetic sum 2.0
13:02:25.034 [main] INFO com.iluwatar.strangler.NewSource -- Source module 2.0
13:02:25.034 [main] INFO com.iluwatar.strangler.NewArithmetic -- Arithmetic mul 2.0
13:02:25.034 [main] INFO com.iluwatar.strangler.NewSource -- Source module 2.0
13:02:25.034 [main] INFO com.iluwatar.strangler.NewArithmetic -- Arithmetic check zero 2.0
13:02:25.035 [main] INFO com.iluwatar.strangler.NewSource -- Source module 2.0
```

--------------------------------

### Main Execution - Example Usage of MapReduce

Source: https://github.com/iluwatar/java-design-patterns/blob/master/map-reduce/README.md

Demonstrates how to run the MapReduce process with sample inputs and prints the resulting aggregated key-value pairs. Ensure Mapper, Shuffler, and Reducer classes are implemented and accessible.

```java
  public static void main(String[] args) {
    List<String> inputs = Arrays.asList(
            "Hello world hello",
            "MapReduce is fun",
            "Hello from the other side",
            "Hello world"
    );
    List<Map.Entry<String, Integer>> result = MapReduce.mapReduce(inputs);
    for (Map.Entry<String, Integer> entry : result) {
        System.out.println(entry.getKey() + ": " + entry.getValue());
    }
}
```

--------------------------------

### Example Usage: Full Publish-Subscribe Flow

Source: https://github.com/iluwatar/java-design-patterns/blob/master/publish-subscribe/README.md

Demonstrates the complete workflow of the Publish-Subscribe pattern. This includes creating a publisher, registering topics, creating and subscribing subscribers, publishing messages, and dynamically managing subscriptions.

```java
public static void main(String[] args) throws InterruptedException {

    final String topicWeather = "WEATHER";
    final String topicTemperature = "TEMPERATURE";
    final String topicCustomerSupport = "CUSTOMER_SUPPORT";

    // 1. create the publisher.
    Publisher publisher = new PublisherImpl();

    // 2. define the topics and register on publisher
    Topic weatherTopic = new Topic(topicWeather);
    publisher.registerTopic(weatherTopic);

    Topic temperatureTopic = new Topic(topicTemperature);
    publisher.registerTopic(temperatureTopic);

    Topic supportTopic = new Topic(topicCustomerSupport);
    publisher.registerTopic(supportTopic);

    // 3. Create the subscribers and subscribe to the relevant topics
    // weatherSub1 will subscribe to two topics WEATHER and TEMPERATURE.
    Subscriber weatherSub1 = new WeatherSubscriber();
    weatherTopic.addSubscriber(weatherSub1);
    temperatureTopic.addSubscriber(weatherSub1);

    // weatherSub2 will subscribe to WEATHER topic
    Subscriber weatherSub2 = new WeatherSubscriber();
    weatherTopic.addSubscriber(weatherSub2);

    // delayedWeatherSub will subscribe to WEATHER topic
    // NOTE :: DelayedWeatherSubscriber has a 0.2 sec delay of processing message.
    Subscriber delayedWeatherSub = new DelayedWeatherSubscriber();
    weatherTopic.addSubscriber(delayedWeatherSub);

    // subscribe the customer support subscribers to the CUSTOMER_SUPPORT topic.
    Subscriber supportSub1 = new CustomerSupportSubscriber();
    supportTopic.addSubscriber(supportSub1);
    Subscriber supportSub2 = new CustomerSupportSubscriber();
    supportTopic.addSubscriber(supportSub2);

    // 4. publish message from each topic
    publisher.publish(weatherTopic, new Message("earthquake"));
    publisher.publish(temperatureTopic, new Message("23C"));
    publisher.publish(supportTopic, new Message("support@test.de"));

    // 5. unregister subscriber from TEMPERATURE topic
    temperatureTopic.removeSubscriber(weatherSub1);

    // 6. publish message under TEMPERATURE topic
    publisher.publish(temperatureTopic, new Message("0C"));

    /*
     * Finally, we wait for the subscribers to consume messages to check the output.
     * The output can change on each run, depending on how long the execution on each
     * subscriber would take
     * Expected behavior:
     * - weatherSub1 will consume earthquake and 23C
     * - weatherSub2 will consume earthquake
     * - delayedWeatherSub will take longer and consume earthquake
     * - supportSub1, supportSub2 will consume support@test.de
     * - the message 0C will not be consumed because weatherSub1 unsubscribed from TEMPERATURE topic
     */
    TimeUnit.SECONDS.sleep(2);
}
```

--------------------------------

### Main Application Entry Point

Source: https://github.com/iluwatar/java-design-patterns/blob/master/ambassador/README.md

Sets up multiple clients and invokes their services to demonstrate the Ambassador Pattern in action.

```java
public class App {
    public static void main(String[] args) {
        var host1 = new Client();
        var host2 = new Client();
        host1.useService(12);
        host2.useService(73);
    }
}
```

--------------------------------

### Program Output of Dependency Injection Example in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/dependency-injection/README.md

The expected output logs from running the dependency injection example, showing which wizard smoked which tobacco.

```text
11:54:05.205 [main] INFO com.iluwatar.dependency.injection.Tobacco -- SimpleWizard smoking OldTobyTobacco
11:54:05.207 [main] INFO com.iluwatar.dependency.injection.Tobacco -- AdvancedWizard smoking SecondBreakfastTobacco
11:54:05.207 [main] INFO com.iluwatar.dependency.injection.Tobacco -- AdvancedSorceress smoking SecondBreakfastTobacco
11:54:05.308 [main] INFO com.iluwatar.dependency.injection.Tobacco -- GuiceWizard smoking RivendellTobacco
```

--------------------------------

### Start Synchronous Event in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/event-based-asynchronous/README.md

Illustrates how a `SyncEvent` is started on the main thread. This blocks the main thread until the event completes, unlike asynchronous events.

```java
@Override
public void start() {
  try {
    handleRunStart();
    Thread.sleep(getRuntime().toMillis());
    handleRunComplete();
  } catch (InterruptedException e) {
    handleRunFailure(e.getMessage());
  }
}
```

--------------------------------

### Pipeline Execution Example

Source: https://github.com/iluwatar/java-design-patterns/blob/master/pipeline/README.md

Demonstrates how to create and execute a pipeline with multiple handlers. The input string is processed sequentially through each added handler.

```java
public static void main(String[] args) {
    LOGGER.info("Creating pipeline");
    var filters = new Pipeline<>(new RemoveAlphabetsHandler())
            .addHandler(new RemoveDigitsHandler())
            .addHandler(new ConvertToCharArrayHandler());
    var input = "GoYankees123!";
    LOGGER.info("Executing pipeline with input: {}", input);
    var output = filters.execute(input);
    LOGGER.info("Pipeline output: {}", output);
}
```

--------------------------------

### Programmatic Example of Strategy Pattern in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/strategy/README.md

This example demonstrates the execution of different strategies for fighting dragons. It shows the output logs when different strategies are applied.

```java
13:06:36.637 [main] INFO com.iluwatar.strategy.App -- Red dragon emerges.
13:06:36.637 [main] INFO com.iluwatar.strategy.LambdaStrategy -- You shoot the dragon with the magical crossbow and it falls dead on the ground!
13:06:36.637 [main] INFO com.iluwatar.strategy.App -- Black dragon lands before you.
13:06:36.637 [main] INFO com.iluwatar.strategy.LambdaStrategy -- You cast the spell of disintegration and the dragon vaporizes in a pile of dust!
```

--------------------------------

### Execute Task with Callback in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/callback/README.md

Demonstrates how to instantiate a task and execute it, providing a callback function that is invoked upon task completion.

```java
public static void main(final String[] args) {
    var task = new SimpleTask();
    task.executeWith(() -> LOGGER.info("I'm done now."));
}
```

--------------------------------

### Main Application Class for Fan-Out/Fan-In Example in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/fanout-fanin/README.md

Drives the Fan-Out/Fan-In pattern example. It initializes numbers, creates SquareNumberRequests, and calls the fanOutFanIn method to process them.

```java
public static void main(String[] args) {
    final List<Long> numbers = Arrays.asList(1L, 3L, 4L, 7L, 8L);

    LOGGER.info("Numbers to be squared and get sum --> {}", numbers);

    final List<SquareNumberRequest> requests =
        numbers.stream().map(SquareNumberRequest::new).toList();

    var consumer = new Consumer(0L);

    // Pass the request and the consumer to fanOutFanIn or sometimes referred as Orchestrator
    // function
    final Long sumOfSquaredNumbers = FanOutFanIn.fanOutFanIn(requests, consumer);

    LOGGER.info("Sum of all squared numbers --> {}", sumOfSquaredNumbers);
}
```

--------------------------------

### Application Entry Point with Update Method Pattern in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/update-method/README.md

Sets up the game world, adds entities, starts the game loop, and stops it after a specified duration.

```java
@Slf4j
public class App {

    private static final int GAME_RUNNING_TIME = 2000;

    public static void main(String[] args) {
        try {
            var world = new World();
            var skeleton1 = new Skeleton(1, 10);
            var skeleton2 = new Skeleton(2, 70);
            var statue = new Statue(3, 20);
            world.addEntity(skeleton1);
            world.addEntity(skeleton2);
            world.addEntity(statue);
            world.run();
            Thread.sleep(GAME_RUNNING_TIME);
            world.stop();
        } catch (InterruptedException e) {
            LOGGER.error(e.getMessage());
        }
    }
}
```

--------------------------------

### Main Application for Throttling Example

Source: https://github.com/iluwatar/java-design-patterns/blob/master/throttling/README.md

Sets up the throttling scenario with different customer limits and simulates service calls using an `ExecutorService`. It demonstrates how the `Bartender` enforces call rates.

```java
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.stream.IntStream;

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class App {

    public static void main(String[] args) {
        var callsCount = new CallsCount();
        var human = new BarCustomer("young human", 2, callsCount);
        var dwarf = new BarCustomer("dwarf soldier", 4, callsCount);

        var executorService = Executors.newFixedThreadPool(2);

        executorService.execute(() -> makeServiceCalls(human, callsCount));
        executorService.execute(() -> makeServiceCalls(dwarf, callsCount));

        executorService.shutdown();
        try {
            if (!executorService.awaitTermination(10, TimeUnit.SECONDS)) {
                executorService.shutdownNow();
            }
        } catch (InterruptedException e) {
            executorService.shutdownNow();
        }
    }

    private static void makeServiceCalls(BarCustomer barCustomer, CallsCount callsCount) {
        var timer = new ThrottleTimerImpl(1000, callsCount);
        var service = new Bartender(timer, callsCount);
        // Sleep is introduced to keep the output in check and easy to view and analyze the results.
        IntStream.range(0, 50).forEach(i -> {
            service.orderDrink(barCustomer);
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                LOGGER.error("Thread interrupted: {}", e.getMessage());
            }
        });
    }
}
```

--------------------------------

### Signup Controller for Signup Page

Source: https://github.com/iluwatar/java-design-patterns/blob/master/page-controller/README.md

Handles GET and POST requests for the /signup path. GET displays the signup page, and POST processes the form and redirects.

```java
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

@Controller
@Component
public class SignupController {
  SignupView view = new SignupView();

  @GetMapping("/signup")
  public String getSignup() {
    return view.display();
  }

  @PostMapping("/signup")
  public String create(SignupModel form, RedirectAttributes redirectAttributes) {
    redirectAttributes.addAttribute("name", form.getName());
    redirectAttributes.addAttribute("email", form.getEmail());
    redirectAttributes.addFlashAttribute("userInfo", form);
    return view.redirect(form);
  }
}
```

--------------------------------

### Main Application Entry Point

Source: https://github.com/iluwatar/java-design-patterns/blob/master/data-locality/README.md

The main method creates a GameEntity, initializes its components, and runs the update loop, demonstrating the pattern's application.

```java
public class Application {
  public static void main(String[] args) {
    var gameEntity = new GameEntity(NUM_ENTITIES);
    gameEntity.start();
    gameEntity.update();
  }
}
```

--------------------------------

### Create, Start, and Manage Synchronous Event in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/event-based-asynchronous/README.md

Demonstrates the lifecycle of a synchronous event using the `EventManager`. This includes creating, starting, checking status, and canceling the event.

```java
EventManager eventManager = new EventManager();

int syncEventId = eventManager.create(Duration.ofSeconds(60));

eventManager.start(syncEventId);

eventManager.status(syncEventId);

eventManager.cancel(syncEventId);
```

--------------------------------

### Client Session Pattern Application Example

Source: https://github.com/iluwatar/java-design-patterns/blob/master/client-session/README.md

Demonstrates the usage of the Server and Session classes by creating sessions, requests, and processing them on the server.

```java
public class App {
  public static void main(String[] args) {
    var server = new Server("localhost", 8080);
    var session1 = server.getSession("Session1");
    var session2 = server.getSession("Session2");
    var request1 = new Request("Data1", session1);
    var request2 = new Request("Data2", session2);
    server.process(request1);
    server.process(request2);
  }
}
```

--------------------------------

### Create, Start, and Manage Asynchronous Event in Java

Source: https://github.com/iluwatar/java-design-patterns/blob/master/event-based-asynchronous/README.md

Demonstrates the lifecycle of an asynchronous event using the `EventManager`. This includes creating, starting, checking status, and canceling the event.

```java
EventManager eventManager = new EventManager();

int asyncEventId = eventManager.createAsync(Duration.ofSeconds(60));

eventManager.start(asyncEventId);

eventManager.status(asyncEventId);

eventManager.cancel(asyncEventId);
```

--------------------------------

### Build Microservices with Maven

Source: https://github.com/iluwatar/java-design-patterns/blob/master/microservices-self-registration/README.md

Navigate to the root directory of each microservice project and execute the Maven clean install command to build them individually.

```bash
cd eurekaserver
mvn clean install
cd ../greetingservice
mvn clean install
cd ../contextservice
mvn clean install
```

--------------------------------

### Spring Boot Application for Single Table Inheritance Example

Source: https://github.com/iluwatar/java-design-patterns/blob/master/single-table-inheritance/README.md

The main application class that sets up and runs the Single Table Inheritance example using Spring Boot and CommandLineRunner.

```java
@SpringBootApplication
@AllArgsConstructor
public class SingleTableInheritance implements CommandLineRunner {

  //Autowiring the VehicleService class to execute the business logic methods
  private final VehicleService vehicleService;

  public static void main(String[] args) {
    SpringApplication.run(SingleTableInheritance.class, args);
  }

  @Override
  public void run(String... args) {

    Logger log = LoggerFactory.getLogger(SingleTableInheritance.class);

    log.info("Saving Vehicles :- ");

    // Saving Car to DB as a Vehicle
    Vehicle vehicle1 = new Car("Tesla", "Model S", 4, 825);
    Vehicle car1 = vehicleService.saveVehicle(vehicle1);
    log.info("Vehicle 1 saved : {}", car1);

    // Saving Truck to DB as a Vehicle
    Vehicle vehicle2 = new Truck("Ford", "F-150", 3325, 14000);
    Vehicle truck1 = vehicleService.saveVehicle(vehicle2);
    log.info("Vehicle 2 saved : {}\n", truck1);


    log.info("Fetching Vehicles :- ");

    // Fetching the Car from DB
    Car savedCar1 = (Car) vehicleService.getVehicle(vehicle1.getVehicleId());
    log.info("Fetching Car1 from DB : {}", savedCar1);

    // Fetching the Truck from DB
    Truck savedTruck1 = (Truck) vehicleService.getVehicle(vehicle2.getVehicleId());
    log.info("Fetching Truck1 from DB : {}\n", savedTruck1);

    log.info("Fetching All Vehicles :- ");

    // Fetching the Vehicles present in the DB
    List<Vehicle> allVehiclesFromDb = vehicleService.getAllVehicles();
    allVehiclesFromDb.forEach(s -> log.info(s.toString()));
  }
}
```

--------------------------------

### Demonstrate Visitor Pattern Usage

Source: https://github.com/iluwatar/java-design-patterns/blob/master/visitor/README.md

This main method sets up an army hierarchy and applies different visitors to showcase their functionality.

```java
public static void main(String[] args) {

    var commander = new Commander(
            new Sergeant(new Soldier(), new Soldier(), new Soldier()),
            new Sergeant(new Soldier(), new Soldier(), new Soldier())
    );
    commander.accept(new SoldierVisitor());
    commander.accept(new SergeantVisitor());
    commander.accept(new CommanderVisitor());
}
```

--------------------------------

### Dynamic Proxy Example Output

Source: https://github.com/iluwatar/java-design-patterns/blob/master/dynamic-proxy/README.md

This output shows the console logs generated by the dynamic proxy example. It highlights the intercepted method calls and the data retrieved from the proxied service.

```log
16:05:41.964 [main] INFO com.iluwatar.dynamicproxy.AlbumInvocationHandler -- ===== Calling the method AlbumService.readAlbums()
16:05:42.409 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=1, title=quidem molestiae enim, userId=1)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=2, title=sunt qui excepturi placeat culpa, userId=1)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=3, title=omnis laborum odio, userId=1)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=4, title=non esse culpa molestiae omnis sed optio, userId=1)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=5, title=eaque aut omnis a, userId=1)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=6, title=natus impedit quibusdam illo est, userId=1)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=7, title=quibusdam autem aliquid et et quia, userId=1)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=8, title=qui fuga est a eum, userId=1)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=9, title=saepe unde necessitatibus rem, userId=1)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=10, title=distinctio laborum qui, userId=1)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=11, title=quam nostrum impedit mollitia quod et dolor, userId=2)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=12, title=consequatur autem doloribus natus consectetur, userId=2)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=13, title=ab rerum non rerum consequatur ut ea unde, userId=2)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=14, title=ducimus molestias eos animi atque nihil, userId=2)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=15, title=ut pariatur rerum ipsum natus repellendus praesentium, userId=2)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=16, title=voluptatem aut maxime inventore autem magnam atque repellat, userId=2)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=17, title=aut minima voluptatem ut velit, userId=2)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=18, title=nesciunt quia et doloremque, userId=2)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=19, title=velit pariatur quaerat similique libero omnis quia, userId=2)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=20, title=voluptas rerum iure ut enim, userId=2)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=21, title=repudiandae voluptatem optio est consequatur rem in temporibus et, userId=3)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=22, title=et rem non provident vel ut, userId=3)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=23, title=incidunt quisquam hic adipisci sequi, userId=3)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=24, title=dolores ut et facere placeat, userId=3)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=25, title=vero maxime id possimus sunt neque et consequatur, userId=3)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=26, title=quibusdam saepe ipsa vel harum, userId=3)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=27, title=id non nostrum expedita, userId=3)
16:05:42.410 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=28, title=omnis neque exercitationem sed dolor atque maxime aut cum, userId=3)
16:05:42.411 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=29, title=inventore ut quasi magnam itaque est fugit, userId=3)
16:05:42.411 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=30, title=tempora assumenda et similique odit distinctio error, userId=3)
16:05:42.411 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=31, title=adipisci laborum fuga laboriosam, userId=4)
16:05:42.411 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=32, title=reiciendis dolores a ut qui debitis non quo labore, userId=4)
16:05:42.411 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=33, title=iste eos nostrum, userId=4)
16:05:42.411 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=34, title=cumque voluptatibus rerum architecto blanditiis, userId=4)
16:05:42.411 [main] INFO com.iluwatar.dynamicproxy.App -- Album(id=35, title=et impedit nisi quae magni necessitatibus sed aut pariatur, userId=4)
```