BAEL-1327 Java Threads: notify and wait (initial commit) (#3160)

core-java-concurrency/src/main/java/com/baeldung/concurrent/waitandnotify/Data.java

@@ -0,0 +1,33 @@
+package com.baeldung.concurrent.waitandnotify;
+
+public class Data {
+    private String packet;
+    
+    // True if receiver should wait
+    // False if sender should wait
+    private boolean transfer = true;
+ 
+    public synchronized String receive() {
+        while (transfer) {
+            try {
+                wait();
+            } catch (InterruptedException e) {}
+        }
+        transfer = true;
+
+        notifyAll();
+        return packet;
+    }
+ 
+    public synchronized void send(String packet) {
+        while (!transfer) {
+            try { 
+                wait();
+            } catch (InterruptedException e) {}
+        }
+        transfer = false;
+        
+        this.packet = packet;
+        notifyAll();
+    }
+}

core-java-concurrency/src/main/java/com/baeldung/concurrent/waitandnotify/NetworkDriver.java

@@ -0,0 +1,12 @@
+package com.baeldung.concurrent.waitandnotify;
+
+public class NetworkDriver {
+    public static void main(String[] args) {
+        Data data = new Data();
+        Thread sender = new Thread(new Sender(data));
+        Thread receiver = new Thread(new Receiver(data));
+        
+        sender.start();
+        receiver.start();
+    }
+}

core-java-concurrency/src/main/java/com/baeldung/concurrent/waitandnotify/Receiver.java

@@ -0,0 +1,25 @@
+package com.baeldung.concurrent.waitandnotify;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+public class Receiver implements Runnable {
+    private Data load;
+ 
+    public Receiver(Data load) {
+        this.load = load;
+    }
+ 
+    public void run() {
+        for(String receivedMessage = load.receive();
+          !"End".equals(receivedMessage) ;
+          receivedMessage = load.receive()) {
+            
+            System.out.println(receivedMessage);
+
+            //Thread.sleep() to mimic heavy server-side processing
+            try {
+                Thread.sleep(ThreadLocalRandom.current().nextInt(1000, 5000));
+            } catch (InterruptedException e) {}
+        }
+    }
+}

core-java-concurrency/src/main/java/com/baeldung/concurrent/waitandnotify/Sender.java

@@ -0,0 +1,30 @@
+package com.baeldung.concurrent.waitandnotify;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+public class Sender implements Runnable {
+    private Data data;
+ 
+    public Sender(Data data) {
+        this.data = data;
+    }
+ 
+    public void run() {
+        String packets[] = {
+            "First packet",
+            "Second packet",
+            "Third packet",
+            "Fourth packet",
+            "End"
+        };
+ 
+        for (String packet : packets) {
+            data.send(packet);
+            
+            //Thread.sleep() to mimic heavy server-side processing
+            try {
+                Thread.sleep(ThreadLocalRandom.current().nextInt(1000, 5000));
+            } catch (InterruptedException e) {}
+        }
+    }
+}