Refactored Interactos and use cases. Added ThreadExecutor. Some modifications to UserListPresenter

data/src/main/java/com/fernandocejas/android10/sample/data/executor/JobExecutor.java

@@ -0,0 +1,56 @@
+/**
+ * Copyright (C) 2014 android10.org. All rights reserved.
+ * @author Fernando Cejas (the android10 coder)
+ */
+package com.fernandocejas.android10.sample.data.executor;
+
+import com.fernandocejas.android10.sample.domain.executor.ThreadExecutor;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Decorated {@link java.util.concurrent.ThreadPoolExecutor} Singleton class based on
+ * 'Initialization on Demand Holder' pattern.
+ */
+public class JobExecutor implements ThreadExecutor {
+
+  private static class LazyHolder {
+    private static final JobExecutor INSTANCE = new JobExecutor();
+  }
+
+  public static JobExecutor getInstance() {
+    return LazyHolder.INSTANCE;
+  }
+
+  private static final int INITIAL_POOL_SIZE = 3;
+  private static final int MAX_POOL_SIZE = 5;
+
+  // Sets the amount of time an idle thread waits before terminating
+  private static final int KEEP_ALIVE_TIME = 10;
+
+  // Sets the Time Unit to seconds
+  private static final TimeUnit KEEP_ALIVE_TIME_UNIT = TimeUnit.SECONDS;
+
+  private final BlockingQueue<Runnable> workQueue;
+
+  private final ThreadPoolExecutor threadPoolExecutor;
+
+  private JobExecutor() {
+    this.workQueue = new LinkedBlockingQueue<Runnable>();
+    this.threadPoolExecutor = new ThreadPoolExecutor(INITIAL_POOL_SIZE, MAX_POOL_SIZE,
+        KEEP_ALIVE_TIME, KEEP_ALIVE_TIME_UNIT, this.workQueue);
+  }
+
+  /**
+   * {@inheritDoc}
+   * @param runnable The class that implements {@link Runnable} interface.
+   */
+  @Override public void execute(Runnable runnable) {
+    if (runnable == null) {
+      throw new IllegalArgumentException("Runnable to execute cannot be null");
+    }
+    this.threadPoolExecutor.execute(runnable);
+  }
+}

domain/src/main/java/com/fernandocejas/android10/sample/domain/executor/PostExecutionThread.java

@@ -5,12 +5,15 @@
 package com.fernandocejas.android10.sample.domain.executor;
 
 /**
- * UI thread abstraction created to change the execution context from any thread to the UI thread.
+ * Thread abstraction created to change the execution context from any thread to any other thread.
+ * Useful to encapsulate a UI Thread for example, since some job will be done in background, an
+ * implementation of this interface will change context and update the UI.
  */
-public interface MainThread {
+public interface PostExecutionThread {
   /**
    * Causes the {@link Runnable} to be added to the message queue of the Main UI Thread
    * of the application.
+   *
    * @param runnable {@link Runnable} to be executed.
    */
   void post(Runnable runnable);

domain/src/main/java/com/fernandocejas/android10/sample/domain/executor/ThreadExecutor.java

@@ -12,13 +12,7 @@ import com.fernandocejas.android10.sample.domain.interactor.Interactor;
  *
  * Use this class to execute an {@link Interactor}.
  */
-public interface Executor {
-  /**
-   * Executes an {@link Interactor} by creating a new runnable and execute its run() method.
-   * @param interactor The {@link Interactor} to execute.
-   */
-  void execute(final Interactor interactor);
-
+public interface ThreadExecutor {
   /**
    * Executes a {@link Runnable}.
    * @param runnable The class that implements {@link Runnable} interface.

domain/src/main/java/com/fernandocejas/android10/sample/domain/interactor/GetUserListUseCase.java

@@ -9,13 +9,24 @@ import com.fernandocejas.android10.sample.domain.exception.ErrorBundle;
 import java.util.Collection;
 
 /**
- *
+ * This interface represents a execution unit for a use case to get a collection of {@link User}.
+ * By convention this use case (Interactor) implementation will return the result using a Callback.
+ * That callback should be executed in the UI thread.
  */
 public interface GetUserListUseCase extends Interactor {
+  /**
+   * Callback used to be notified when either a users collection has been loaded or an error
+   * happened.
+   */
   interface Callback {
     void onUserListLoaded(Collection<User> usersCollection);
     void onError(ErrorBundle errorBundle);
   }
 
-  void getUserList(Callback callback);
+  /**
+   * Executes this user case.
+   *
+   * @param callback A {@link GetUserListUseCase.Callback} used to notify the client.
+   */
+  void execute(Callback callback);
 }

domain/src/main/java/com/fernandocejas/android10/sample/domain/interactor/GetUserListUseCaseImpl.java

@@ -4,35 +4,79 @@
  */
 package com.fernandocejas.android10.sample.domain.interactor;
 
+import com.fernandocejas.android10.sample.domain.User;
+import com.fernandocejas.android10.sample.domain.exception.ErrorBundle;
+import com.fernandocejas.android10.sample.domain.executor.PostExecutionThread;
+import com.fernandocejas.android10.sample.domain.executor.ThreadExecutor;
 import com.fernandocejas.android10.sample.domain.repository.UserRepository;
+import java.util.Collection;
 import java.util.Collections;
 
 /**
- *
+ * This class is an implementation of {@link GetUserListUseCase} that represents a use case for
+ * retrieving a collection of all {@link User}.
  */
 public class GetUserListUseCaseImpl implements GetUserListUseCase {
 
   private final UserRepository userRepository;
+  private final ThreadExecutor threadExecutor;
+  private final PostExecutionThread postExecutionThread;
 
-  public GetUserListUseCaseImpl(UserRepository userRepository) {
-    if (userRepository == null) {
+  private Callback callback;
+
+  /**
+   * Constructor of the class.
+   *
+   * @param userRepository A {@link UserRepository} as a source for retrieving data.
+   * @param threadExecutor {@link ThreadExecutor} used to execute this use case in a background thread.
+   * @param postExecutionThread {@link PostExecutionThread} used to post updates when the use case has been executed.
+   */
+  public GetUserListUseCaseImpl(UserRepository userRepository, ThreadExecutor threadExecutor,
+      PostExecutionThread postExecutionThread) {
+    if (userRepository == null || threadExecutor == null || postExecutionThread == null) {
       throw new IllegalArgumentException("Constructor parameters cannot be null!!!");
     }
     this.userRepository = userRepository;
+    this.threadExecutor = threadExecutor;
+    this.postExecutionThread = postExecutionThread;
+  }
+
+  @Override public void execute(Callback callback) {
+    if (callback == null) {
+      throw new IllegalArgumentException("Interactor callback cannot be null!!!");
+    }
+    this.callback = callback;
+    this.threadExecutor.execute(this);
   }
 
   @Override public void run() {
-
+    this.userRepository.getUserList(this.repositoryCallback);
   }
 
-  @Override public void getUserList(Callback callback) {
-    //doing some fake job
-    try {
-      Thread.sleep(6000);
-    } catch (InterruptedException e) {
-      e.printStackTrace();
+  private final UserRepository.UserListCallback repositoryCallback =
+      new UserRepository.UserListCallback() {
+    @Override public void onUserListLoaded(Collection<User> usersCollection) {
+      notifyGetUserListSuccessfully(usersCollection);
     }
-    // should this be in a new thread?
-    callback.onUserListLoaded(Collections.unmodifiableCollection(Collections.EMPTY_LIST));
+
+    @Override public void onError(ErrorBundle errorBundle) {
+      notifyError(errorBundle);
+    }
+  };
+
+  private void notifyGetUserListSuccessfully(final Collection<User> usersCollection) {
+    this.postExecutionThread.post(new Runnable() {
+      @Override public void run() {
+        callback.onUserListLoaded(Collections.unmodifiableCollection(usersCollection));
+      }
+    });
+  }
+
+  private void notifyError(final ErrorBundle errorBundle) {
+    this.postExecutionThread.post(new Runnable() {
+      @Override public void run() {
+        callback.onError(errorBundle);
+      }
+    });
   }
 }

domain/src/main/java/com/fernandocejas/android10/sample/domain/interactor/Interactor.java

@@ -5,13 +5,14 @@
 package com.fernandocejas.android10.sample.domain.interactor;
 
 /**
- * Common interface for an interactor declared in the application.
- * This interface represents a execution unit for different use cases.
+ * Common interface for an Interactor {@link java.lang.Runnable} declared in the application.
+ * This interface represents a execution unit for different use cases (this means any use case
+ * in the application should implement this contract).
  *
- * By convention each interactor implementation will return the result using a Callback should be
- * executed in the UI thread.
+ * By convention each Interactor implementation will return the result using a Callback that should
+ * be executed in the UI thread.
  */
-public interface Interactor {
+public interface Interactor extends Runnable {
   /**
    * Everything inside this method will be executed asynchronously.
    */

domain/src/main/java/com/fernandocejas/android10/sample/domain/repository/UserRepository.java

@@ -17,7 +17,6 @@ public interface UserRepository {
    */
   interface UserCallback {
     void onUserLoaded(User user);
-
     void onError(ErrorBundle errorBundle);
   }
 
@@ -25,8 +24,7 @@ public interface UserRepository {
    * Callback used to be notified when either a user list has been loaded or an error happened.
    */
   interface UserListCallback {
-    void onUserListLoaded(Collection<User> user);
-
+    void onUserListLoaded(Collection<User> usersCollection);
     void onError(ErrorBundle errorBundle);
   }
 

presentation/src/main/java/com/fernandocejas/android10/sample/presentation/UIThread.java

@@ -0,0 +1,40 @@
+/**
+ * Copyright (C) 2014 android10.org. All rights reserved.
+ * @author Fernando Cejas (the android10 coder)
+ */
+package com.fernandocejas.android10.sample.presentation;
+
+import android.os.Handler;
+import android.os.Looper;
+import com.fernandocejas.android10.sample.domain.executor.PostExecutionThread;
+
+/**
+ * MainThread (UI Thread) implementation based on a Handler instantiated with the main
+ * application Looper.
+ */
+public class UIThread implements PostExecutionThread {
+
+  private static class LazyHolder {
+    private static final UIThread INSTANCE = new UIThread();
+  }
+
+  public static UIThread getInstance() {
+    return LazyHolder.INSTANCE;
+  }
+
+  private final Handler handler;
+
+  private UIThread() {
+    this.handler = new Handler(Looper.getMainLooper());
+  }
+
+  /**
+   * Causes the Runnable r to be added to the message queue.
+   * The runnable will be run on the main thread.
+   *
+   * @param runnable {@link Runnable} to be executed.
+   */
+  @Override public void post(Runnable runnable) {
+    handler.post(runnable);
+  }
+}

presentation/src/main/java/com/fernandocejas/android10/sample/presentation/presenter/BasePresenter.java

@@ -1,34 +0,0 @@
-/**
- * Copyright (C) 2014 android10.org. All rights reserved.
- * @author Fernando Cejas (the android10 coder)
- */
-package com.fernandocejas.android10.sample.presentation.presenter;
-
-import com.fernandocejas.android10.sample.domain.interactor.Interactor;
-
-/**
- * Abstract class representing a Presenter in a model view presenter (MVP) pattern.
- */
-public abstract class BasePresenter {
-  /**
-   * Method that control the lifecycle of the view. It should be called in the view's
-   * (Activity or Fragment) onResume() method.
-   */
-  public abstract void resume();
-
-  /**
-   * Method that control the lifecycle of the view. It should be called in the view's
-   * (Activity or Fragment) onPause() method.
-   */
-  public abstract void pause();
-
-  /**
-   * Executes an {@link Interactor} asynchronously in a new thread.
-   * @param interactor The {@link Interactor} to execute.
-   */
-  protected void executeInteractorAsync(Interactor interactor) {
-    if (interactor == null) {
-      throw new IllegalArgumentException("Interactor to execute cannot be null");
-    }
-  }
-}

presentation/src/main/java/com/fernandocejas/android10/sample/presentation/presenter/Presenter.java

@@ -0,0 +1,22 @@
+/**
+ * Copyright (C) 2014 android10.org. All rights reserved.
+ * @author Fernando Cejas (the android10 coder)
+ */
+package com.fernandocejas.android10.sample.presentation.presenter;
+
+/**
+ * Interface representing a Presenter in a model view presenter (MVP) pattern.
+ */
+public interface Presenter {
+  /**
+   * Method that control the lifecycle of the view. It should be called in the view's
+   * (Activity or Fragment) onResume() method.
+   */
+  void resume();
+
+  /**
+   * Method that control the lifecycle of the view. It should be called in the view's
+   * (Activity or Fragment) onPause() method.
+   */
+  void pause();
+}

presentation/src/main/java/com/fernandocejas/android10/sample/presentation/presenter/UserListPresenter.java

@@ -13,10 +13,7 @@ import com.fernandocejas.android10.sample.presentation.model.UserModel;
 import com.fernandocejas.android10.sample.presentation.view.UserListView;
 import java.util.Collection;
 
-/**
- *
- */
-public class UserListPresenter extends BasePresenter {
+public class UserListPresenter implements Presenter {
 
   private final UserListView viewListView;
   private final GetUserListUseCase getUserListUseCase;
@@ -36,9 +33,7 @@ public class UserListPresenter extends BasePresenter {
     this.loadUserList();
   }
 
-  @Override public void pause() {
-    //nothing to do here
-  }
+  @Override public void pause() {}
 
   /**
    * Loads all users.
@@ -78,7 +73,7 @@ public class UserListPresenter extends BasePresenter {
   }
 
   private void getUserList() {
-    this.getUserListUseCase.getUserList(userListCallback);
+    this.getUserListUseCase.execute(userListCallback);
   }
 
   private final GetUserListUseCase.Callback userListCallback = new GetUserListUseCase.Callback() {

presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/BaseFragment.java

@@ -24,7 +24,7 @@ public abstract class BaseFragment extends Fragment {
   }
 
   /**
-   * Initializes the {@link com.fernandocejas.android10.sample.presentation.presenter.BasePresenter}
+   * Initializes the {@link com.fernandocejas.android10.sample.presentation.presenter.Presenter}
    * for this fragment in a MVP pattern used to architect the application presentation layer.
    */
   abstract void initializePresenter();

presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/UserListFragment.java

@@ -13,12 +13,16 @@ import android.widget.Button;
 import android.widget.RelativeLayout;
 import android.widget.Toast;
 import com.fernandocejas.android10.sample.data.entity.mapper.UserEntityDataMapper;
+import com.fernandocejas.android10.sample.data.executor.JobExecutor;
 import com.fernandocejas.android10.sample.data.repository.UserDataRepository;
 import com.fernandocejas.android10.sample.data.repository.datasource.UserDataStoreFactory;
+import com.fernandocejas.android10.sample.domain.executor.PostExecutionThread;
+import com.fernandocejas.android10.sample.domain.executor.ThreadExecutor;
 import com.fernandocejas.android10.sample.domain.interactor.GetUserListUseCase;
 import com.fernandocejas.android10.sample.domain.interactor.GetUserListUseCaseImpl;
 import com.fernandocejas.android10.sample.domain.repository.UserRepository;
 import com.fernandocejas.android10.sample.presentation.R;
+import com.fernandocejas.android10.sample.presentation.UIThread;
 import com.fernandocejas.android10.sample.presentation.mapper.UserModelDataMapper;
 import com.fernandocejas.android10.sample.presentation.model.UserModel;
 import com.fernandocejas.android10.sample.presentation.presenter.UserListPresenter;
@@ -65,10 +69,18 @@ public class UserListFragment extends BaseFragment implements UserListView {
     // LEARNING EXAMPLE PURPOSE.
     UserDataStoreFactory userDataStoreFactory = new UserDataStoreFactory(this.getContext());
     UserEntityDataMapper userEntityDataMapper = new UserEntityDataMapper();
+
     UserRepository userRepository = UserDataRepository.getInstance(userDataStoreFactory,
         userEntityDataMapper);
-    GetUserListUseCase getUserListUseCase = new GetUserListUseCaseImpl(userRepository);
+
+    ThreadExecutor threadExecutor = JobExecutor.getInstance();
+    PostExecutionThread postExecutionThread = UIThread.getInstance();
+
+    GetUserListUseCase getUserListUseCase = new GetUserListUseCaseImpl(userRepository,
+        threadExecutor, postExecutionThread);
+
     UserModelDataMapper userModelDataMapper = new UserModelDataMapper();
+
     this.userListPresenter = new UserListPresenter(this, getUserListUseCase, userModelDataMapper);
   }