Resolves checkstyle errors for guarded-suspension, half-sync-half-async, hexagonal (iluwatar#1064)

* Reduces checkstyle errors in guarded-suspension

* Reduces checkstyle errors in half-sync-half-async

* Reduces checkstyle errors in hexagonal

Author: anuragagarwal561994

guarded-suspension/src/main/java/com/iluwatar/guarded/suspension/App.java

@@ -21,15 +21,6 @@
  * THE SOFTWARE.
  */
 
-/**
- * Guarded-suspension is a concurrent design pattern for handling situation when to execute some action we need
- * condition to be satisfied.
- * <p>
- * Implementation is based on GuardedQueue, which has two methods: get and put,
- * the condition is that we cannot get from empty queue so when thread attempt
- * to break the condition we invoke Object's wait method on him and when other thread put an element
- * to the queue he notify the waiting one that now he can get from queue.
- */
 package com.iluwatar.guarded.suspension;
 
 import java.util.concurrent.ExecutorService;
@@ -38,10 +29,18 @@
 
 /**
  * Created by robertt240 on 1/26/17.
+ *
+ * <p>Guarded-suspension is a concurrent design pattern for handling situation when to execute some
+ * action we need condition to be satisfied.
+ *
+ * <p>Implementation is based on GuardedQueue, which has two methods: get and put, the condition is
+ * that we cannot get from empty queue so when thread attempt to break the condition we invoke
+ * Object's wait method on him and when other thread put an element to the queue he notify the
+ * waiting one that now he can get from queue.
  */
 public class App {
   /**
-   * Example pattern execution
+   * Example pattern execution.
    *
    * @param args - command line args
    */
@@ -55,13 +54,15 @@ public static void main(String[] args) {
         }
     );
 
-    //here we wait two seconds to show that the thread which is trying to get from guardedQueue will be waiting
+    // here we wait two seconds to show that the thread which is trying
+    // to get from guardedQueue will be waiting
     try {
       Thread.sleep(2000);
     } catch (InterruptedException e) {
       e.printStackTrace();
     }
-    //now we execute second thread which will put number to guardedQueue and notify first thread that it could get
+    // now we execute second thread which will put number to guardedQueue
+    // and notify first thread that it could get
     executorService.execute(() -> {
           guardedQueue.put(20);
         }

guarded-suspension/src/main/java/com/iluwatar/guarded/suspension/GuardedQueue.java

@@ -23,16 +23,16 @@
 
 package com.iluwatar.guarded.suspension;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.LinkedList;
 import java.util.Queue;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
- * Guarded Queue is an implementation for Guarded Suspension Pattern
- * Guarded suspension pattern is used to handle a situation when you want to execute a method
- * on an object which is not in a proper state.
+ * Guarded Queue is an implementation for Guarded Suspension Pattern Guarded suspension pattern is
+ * used to handle a situation when you want to execute a method on an object which is not in a
+ * proper state.
+ *
  * @see <a href="http://java-design-patterns.com/patterns/guarded-suspension/">http://java-design-patterns.com/patterns/guarded-suspension/</a>
  */
 public class GuardedQueue {
@@ -44,6 +44,8 @@ public GuardedQueue() {
   }
 
   /**
+   * Get the last element of the queue is exists.
+   *
    * @return last element of a queue if queue is not empty
    */
   public synchronized Integer get() {
@@ -60,6 +62,8 @@ public synchronized Integer get() {
   }
 
   /**
+   * Put a value in the queue.
+   *
    * @param e number which we want to put to our queue
    */
   public synchronized void put(Integer e) {

half-sync-half-async/src/main/java/com/iluwatar/halfsynchalfasync/App.java

@@ -23,58 +23,50 @@
 
 package com.iluwatar.halfsynchalfasync;
 
+import java.util.concurrent.LinkedBlockingQueue;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.concurrent.LinkedBlockingQueue;
-
 /**
- * 
- * This application demonstrates Half-Sync/Half-Async pattern. Key parts of the pattern are
- * {@link AsyncTask} and {@link AsynchronousService}.
- * 
- * <p>
- * <i>PROBLEM</i> <br>
+ * This application demonstrates Half-Sync/Half-Async pattern. Key parts of the pattern are {@link
+ * AsyncTask} and {@link AsynchronousService}.
+ *
+ * <p><i>PROBLEM</i> <br>
  * A concurrent system have a mixture of short duration, mid duration and long duration tasks. Mid
  * or long duration tasks should be performed asynchronously to meet quality of service
  * requirements.
- * 
- * <p>
- * <i>INTENT</i> <br>
+ *
+ * <p><i>INTENT</i> <br>
  * The intent of this pattern is to separate the the synchronous and asynchronous processing in the
  * concurrent application by introducing two intercommunicating layers - one for sync and one for
  * async. This simplifies the programming without unduly affecting the performance.
- * 
- * <p>
- * <i>APPLICABILITY</i> <br>
- * UNIX network subsystems - In operating systems network operations are carried out
- * asynchronously with help of hardware level interrupts.<br>
- * CORBA - At the asynchronous layer one thread is associated with each socket that is connected
- * to the client. Thread blocks waiting for CORBA requests from the client. On receiving request it
- * is inserted in the queuing layer which is then picked up by synchronous layer which processes the
- * request and sends response back to the client.<br>
- * Android AsyncTask framework - Framework provides a way to execute long running blocking
- * calls, such as downloading a file, in background threads so that the UI thread remains free to
- * respond to user inputs.<br>
- * 
- * <p>
- * <i>IMPLEMENTATION</i> <br>
+ *
+ * <p><i>APPLICABILITY</i> <br>
+ * UNIX network subsystems - In operating systems network operations are carried out asynchronously
+ * with help of hardware level interrupts.<br> CORBA - At the asynchronous layer one thread is
+ * associated with each socket that is connected to the client. Thread blocks waiting for CORBA
+ * requests from the client. On receiving request it is inserted in the queuing layer which is then
+ * picked up by synchronous layer which processes the request and sends response back to the
+ * client.<br> Android AsyncTask framework - Framework provides a way to execute long running
+ * blocking calls, such as downloading a file, in background threads so that the UI thread remains
+ * free to respond to user inputs.<br>
+ *
+ * <p><i>IMPLEMENTATION</i> <br>
  * The main method creates an asynchronous service which does not block the main thread while the
  * task is being performed. The main thread continues its work which is similar to Async Method
  * Invocation pattern. The difference between them is that there is a queuing layer between
  * Asynchronous layer and synchronous layer, which allows for different communication patterns
  * between both layers. Such as Priority Queue can be used as queuing layer to prioritize the way
  * tasks are executed. Our implementation is just one simple way of implementing this pattern, there
  * are many variants possible as described in its applications.
- * 
  */
 public class App {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
 
   /**
-   * Program entry point
-   * 
+   * Program entry point.
+   *
    * @param args command line args
    */
   public static void main(String[] args) {
@@ -100,15 +92,13 @@ public static void main(String[] args) {
   }
 
   /**
-   * 
-   * ArithmeticSumTask
-   *
+   * ArithmeticSumTask.
    */
   static class ArithmeticSumTask implements AsyncTask<Long> {
-    private long n;
+    private long numberOfElements;
 
-    public ArithmeticSumTask(long n) {
-      this.n = n;
+    public ArithmeticSumTask(long numberOfElements) {
+      this.numberOfElements = numberOfElements;
     }
 
     /*
@@ -117,7 +107,7 @@ public ArithmeticSumTask(long n) {
      */
     @Override
     public Long call() throws Exception {
-      return ap(n);
+      return ap(numberOfElements);
     }
 
     /*
@@ -128,7 +118,7 @@ public Long call() throws Exception {
      */
     @Override
     public void onPreCall() {
-      if (n < 0) {
+      if (numberOfElements < 0) {
         throw new IllegalArgumentException("n is less than 0");
       }
     }

half-sync-half-async/src/main/java/com/iluwatar/halfsynchalfasync/AsyncTask.java

@@ -30,7 +30,7 @@
  * typically done is background threads and the result is posted back in form of callback. The
  * callback does not implement {@code isComplete}, {@code cancel} as it is out of scope of this
  * pattern.
- * 
+ *
  * @param <O> type of result
  */
 public interface AsyncTask<O> extends Callable<O> {
@@ -53,7 +53,7 @@ public interface AsyncTask<O> extends Callable<O> {
   /**
    * A callback called if computing the task resulted in some exception. This method is called when
    * either of {@link #call()} or {@link #onPreCall()} throw any exception.
-   * 
+   *
    * @param throwable error cause
    */
   void onError(Throwable throwable);

half-sync-half-async/src/main/java/com/iluwatar/halfsynchalfasync/AsynchronousService.java

@@ -23,15 +23,14 @@
 
 package com.iluwatar.halfsynchalfasync;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.FutureTask;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * This is the asynchronous layer which does not block when a new request arrives. It just passes
@@ -63,13 +62,14 @@ public AsynchronousService(BlockingQueue<Runnable> workQueue) {
 
   /**
    * A non-blocking method which performs the task provided in background and returns immediately.
-   * <p>
-   * On successful completion of task the result is posted back using callback method
-   * {@link AsyncTask#onPostCall(Object)}, if task execution is unable to complete normally due to
-   * some exception then the reason for error is posted back using callback method
-   * {@link AsyncTask#onError(Throwable)}.
-   * <p>
-   * NOTE: The results are posted back in the context of background thread in this implementation.
+   *
+   * <p>On successful completion of task the result is posted back using callback method {@link
+   * AsyncTask#onPostCall(Object)}, if task execution is unable to complete normally due to some
+   * exception then the reason for error is posted back using callback method {@link
+   * AsyncTask#onError(Throwable)}.
+   *
+   * <p>NOTE: The results are posted back in the context of background thread in this
+   * implementation.
    */
   public <T> void execute(final AsyncTask<T> task) {
     try {

hexagonal/src/main/java/com/iluwatar/hexagonal/App.java

@@ -31,40 +31,35 @@
 import com.iluwatar.hexagonal.sampledata.SampleData;
 
 /**
- * 
- * Hexagonal Architecture pattern decouples the application core from the
- * services it uses. This allows the services to be plugged in and the 
- * application will run with or without the services.<p>
- * 
- * The core logic, or business logic, of an application consists of the 
- * algorithms that are essential to its purpose. They implement the use 
- * cases that are the heart of the application. When you change them, you 
- * change the essence of the application.<p>
- * 
- * The services are not essential. They can be replaced without changing 
- * the purpose of the application. Examples: database access and other 
- * types of storage, user interface components, e-mail and other 
- * communication components, hardware devices.<p>
- * 
- * This example demonstrates Hexagonal Architecture with a lottery system.
- * The application core is separate from the services that drive it and
- * from the services it uses.<p>
- * 
- * The primary ports for the application are console interfaces
- * {@link com.iluwatar.hexagonal.administration.ConsoleAdministration} through which the lottery round is
- * initiated and run and {@link com.iluwatar.hexagonal.service.ConsoleLottery} that allows players to
- * submit lottery tickets for the draw.<p>
- * 
- * The secondary ports that application core uses are {@link com.iluwatar.hexagonal.banking.WireTransfers}
- * which is a banking service, {@link com.iluwatar.hexagonal.eventlog.LotteryEventLog} that delivers
- * eventlog as lottery events occur and {@link com.iluwatar.hexagonal.database.LotteryTicketRepository}
- * that is the storage for the lottery tickets.
+ * Hexagonal Architecture pattern decouples the application core from the services it uses. This
+ * allows the services to be plugged in and the application will run with or without the services.
  *
+ * <p>The core logic, or business logic, of an application consists of the algorithms that are
+ * essential to its purpose. They implement the use cases that are the heart of the application.
+ * When you change them, you change the essence of the application.
+ *
+ * <p>The services are not essential. They can be replaced without changing the purpose of the
+ * application. Examples: database access and other types of storage, user interface components,
+ * e-mail and other communication components, hardware devices.
+ *
+ * <p>This example demonstrates Hexagonal Architecture with a lottery system. The application core
+ * is separate from the services that drive it and from the services it uses.
+ *
+ * <p>The primary ports for the application are console interfaces {@link
+ * com.iluwatar.hexagonal.administration.ConsoleAdministration} through which the lottery round is
+ * initiated and run and {@link com.iluwatar.hexagonal.service.ConsoleLottery} that allows players
+ * to submit lottery tickets for the draw.
+ *
+ * <p>The secondary ports that application core uses are{@link
+ * com.iluwatar.hexagonal.banking.WireTransfers} which is a banking service, {@link
+ * com.iluwatar.hexagonal.eventlog.LotteryEventLog} that delivers eventlog as lottery events occur
+ * and {@link com.iluwatar.hexagonal.database.LotteryTicketRepository} that is the storage for the
+ * lottery tickets.
  */
 public class App {
 
   /**
-   * Program entry point
+   * Program entry point.
    */
   public static void main(String[] args) {
 
@@ -73,11 +68,11 @@ public static void main(String[] args) {
     // start new lottery round
     LotteryAdministration administration = injector.getInstance(LotteryAdministration.class);
     administration.resetLottery();
-    
+
     // submit some lottery tickets
     LotteryService service = injector.getInstance(LotteryService.class);
     SampleData.submitTickets(service, 20);
-    
+
     // perform lottery
     administration.performLottery();
   }

hexagonal/src/main/java/com/iluwatar/hexagonal/administration/ConsoleAdministration.java

@@ -30,28 +30,28 @@
 import com.iluwatar.hexagonal.module.LotteryModule;
 import com.iluwatar.hexagonal.mongo.MongoConnectionPropertiesLoader;
 import com.iluwatar.hexagonal.sampledata.SampleData;
+import java.util.Scanner;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.Scanner;
-
 /**
- * Console interface for lottery administration
+ * Console interface for lottery administration.
  */
 public class ConsoleAdministration {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(ConsoleAdministration.class);
 
   /**
-   * Program entry point
+   * Program entry point.
    */
   public static void main(String[] args) {
     MongoConnectionPropertiesLoader.load();
     Injector injector = Guice.createInjector(new LotteryModule());
     LotteryAdministration administration = injector.getInstance(LotteryAdministration.class);
     LotteryService service = injector.getInstance(LotteryService.class);
     SampleData.submitTickets(service, 20);
-    ConsoleAdministrationSrv consoleAdministration = new ConsoleAdministrationSrvImpl(administration, LOGGER);
+    ConsoleAdministrationSrv consoleAdministration =
+        new ConsoleAdministrationSrvImpl(administration, LOGGER);
     try (Scanner scanner = new Scanner(System.in)) {
       boolean exit = false;
       while (!exit) {