Paralal Thread Print round robin - Solution

01/java-basics/src/main/java/org/example/concurrency/MultiThreadPrint.java

@@ -4,27 +4,111 @@ public class MultiThreadPrint {
 
     public static void main(String[] args) {
         /*
-         * print 1-100 3 times in 3 "parallel" threads
+        Th1 - 1
+        Th2 - 1
+        Th3 - 1
+
+        Th1 - 2
+        Th2 - 2
+        Th3 - 2
+
+        Th1 - 3
+        Th2 - 3
+        Th3 - 3
+
          */
+        DataPrinter printer = new DataPrinter();
+        Thread th1 = new SeqGenerator(printer);
+        Thread th2 = new SeqGenerator(printer);
+        Thread th3 = new SeqGenerator(printer);
+
+        th1.start();
+        th2.start();
+        th3.start();
+
+
+    }
+
+    public static class SeqGenerator extends  Thread {
+        DataPrinter printer;
+
+        int endVal =0;
 
-        Runnable r = new Runnable() {
-            @Override
-            public void run() {
-                for (int i = 1; i <= 100; i++) {
-                    System.out.println(Thread.currentThread().getName() + " " + i);
+        public SeqGenerator(int n) {
+            endVal = n;
+        }
+
+        public SeqGenerator(DataPrinter pp) {
+            printer = pp;
+            printer.registerThread(this.getName());
+        }
+
+        @Override
+        public void run() {
+            for (int i=1;i<=10;i++) {
+                try {
+                    printer.print(this.getName(), i);
+                } catch (InterruptedException e) {
+                    throw new RuntimeException(e);
                 }
             }
-        };
-
-        Thread t1 = new Thread(r);
-        Thread t2 = new Thread(r);
-        Thread t3 = new Thread(r);
-        t1.start();
-        t2.start();
-        t3.start();
+        }
+    }
+    public static class DataPrinter  {
+        int curThread = 0;
+
+        List<String> threads = new ArrayList<>();
+        public void registerThread(String threadId) {
+            threads.add(threadId);
+            System.out.println(threadId);
+        }
+
+        public synchronized void print(String thId, int val) throws InterruptedException {
+            while(!threads.get(curThread).equals(thId)) {
+                wait();
+            }
+
+            System.out.println("Thread " + thId + " prints " + val);
+
+            curThread= (curThread + 1) % threads.size();
+            notifyAll();
+        }
     }
+/**
+Output 
 
-    /**
+Thread 0 prints 1
+Thread 1 prints 1
+Thread 2 prints 1
+Thread 0 prints 2
+Thread 1 prints 2
+Thread 2 prints 2
+Thread 0 prints 3
+Thread 1 prints 3
+Thread 2 prints 3
+Thread 0 prints 4
+Thread 1 prints 4
+Thread 2 prints 4
+Thread 0 prints 5
+Thread 1 prints 5
+Thread 2 prints 5
+Thread 0 prints 6
+Thread 1 prints 6
+Thread 2 prints 6
+Thread 0 prints 7
+Thread 1 prints 7
+Thread 2 prints 7
+Thread 0 prints 8
+Thread 1 prints 8
+Thread 2 prints 8
+Thread 0 prints 9
+Thread 1 prints 9
+Thread 2 prints 9
+Thread 0 prints 10
+Thread 1 prints 10
+Thread 2 prints 10
+
+
      * ASSIGNMENT (PROJECT CLASS 01)
      *
      * Write more ways of achieving the above goal.