BAEL-6501 Update article "The producer-consumer problem example in Java" (#13973)

* BAEL-6501 Changed the synchronization block to use the DataQueue

* BAEL-6501 Fixed the platform agnostic new lines

* BAEL-6501 Moved ID increment to a static method

* BAEL-6501 Added a logger

core-java-modules/core-java-concurrency-advanced-4/src/main/java/com/baeldung/producerconsumer/Consumer.java

@@ -1,6 +1,9 @@
 package com.baeldung.producerconsumer;
 
+import java.util.logging.Logger;
+
 public class Consumer implements Runnable {
+    private static final Logger log = Logger.getLogger(Consumer.class.getCanonicalName());
     private final DataQueue dataQueue;
 
     public Consumer(DataQueue dataQueue) {
@@ -14,7 +17,7 @@ public class Consumer implements Runnable {
 
     public void consume() {
         while (dataQueue.runFlag) {
-            synchronized (this) {
+            synchronized (dataQueue) {
                 while (dataQueue.isEmpty() && dataQueue.runFlag) {
                     try {
                         dataQueue.waitOnEmpty();
@@ -31,12 +34,13 @@ public class Consumer implements Runnable {
                 useMessage(message);
             }
         }
-        System.out.println("Consumer Stopped");
+        log.info("Consumer Stopped");
     }
 
     private void useMessage(Message message) {
         if (message != null) {
-            System.out.printf("[%s] Consuming Message. Id: %d, Data: %f\n", Thread.currentThread().getName(), message.getId(), message.getData());
+            log.info(String.format("[%s] Consuming Message. Id: %d, Data: %f%n",
+                Thread.currentThread().getName(), message.getId(), message.getData()));
 
             //Sleeping on random time to make it realistic
             ThreadUtil.sleep((long) (message.getData() * 100));

core-java-modules/core-java-concurrency-advanced-4/src/main/java/com/baeldung/producerconsumer/Producer.java

@@ -1,6 +1,9 @@
 package com.baeldung.producerconsumer;
 
+import java.util.logging.Logger;
+
 public class Producer implements Runnable {
+    private static final Logger log = Logger.getLogger(Producer.class.getCanonicalName());
     private final DataQueue dataQueue;
 
     private static int idSequence = 0;
@@ -16,7 +19,7 @@ public class Producer implements Runnable {
 
     public void produce() {
         while (dataQueue.runFlag) {
-            synchronized (this) {
+            synchronized (dataQueue) {
                 while (dataQueue.isFull() && dataQueue.runFlag) {
                     try {
                         dataQueue.waitOnFull();
@@ -33,12 +36,13 @@ public class Producer implements Runnable {
                 dataQueue.notifyAllForEmpty();
             }
         }
-        System.out.println("Producer Stopped");
+        log.info("Producer Stopped");
     }
 
     private Message generateMessage() {
-        Message message = new Message(++idSequence, Math.random());
+        Message message = new Message(incrementAndGetId(), Math.random());
-        System.out.printf("[%s] Generated Message. Id: %d, Data: %f\n", Thread.currentThread().getName(), message.getId(), message.getData());
+        log.info(String.format("[%s] Generated Message. Id: %d, Data: %f%n",
+            Thread.currentThread().getName(), message.getId(), message.getData()));
 
         //Sleeping on random time to make it realistic
         ThreadUtil.sleep((long) (message.getData() * 100));
@@ -46,6 +50,10 @@ public class Producer implements Runnable {
         return message;
     }
 
+    private static int incrementAndGetId() {
+        return ++idSequence;
+    }
+
     public void stop() {
         dataQueue.runFlag = false;
         dataQueue.notifyAllForFull();

core-java-modules/core-java-concurrency-advanced-4/src/main/java/com/baeldung/producerconsumer/SimpleProducerConsumerDemonstrator.java

@@ -2,10 +2,12 @@ package com.baeldung.producerconsumer;
 
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingDeque;
+import java.util.logging.Logger;
 
 import static com.baeldung.producerconsumer.ThreadUtil.sleep;
 
 public class SimpleProducerConsumerDemonstrator {
+    private static final Logger log = Logger.getLogger(SimpleProducerConsumerDemonstrator.class.getCanonicalName());
     BlockingQueue<Double> blockingQueue = new LinkedBlockingDeque<>(5);
 
     private void produce() {
@@ -17,7 +19,7 @@ public class SimpleProducerConsumerDemonstrator {
                 e.printStackTrace();
                 break;
             }
-            System.out.printf("[%s] Value produced: %f\n", Thread.currentThread().getName(), value);
+            log.info(String.format("[%s] Value produced: %f%n", Thread.currentThread().getName(), value));
         }
     }
 
@@ -31,7 +33,7 @@ public class SimpleProducerConsumerDemonstrator {
                 break;
             }
             // Consume value
-            System.out.printf("[%s] Value consumed: %f\n", Thread.currentThread().getName(), value);
+            log.info(String.format("[%s] Value consumed: %f%n", Thread.currentThread().getName(), value));
         }
     }