3 Threads Printing numbers in sequence

Question

I am trying to write a simple code to print numbers in sequence. Scenario is like

Thread  Number
T1        1
T2        2
T3        3
T1        4
T2        5
T3          


        

Answer 1

public class ThreadTask implements Runnable {

  private int counter; 
  private int threadID;
  private final Object lock;
  private int prev;
  public ThreadTask(Object obj, int threadid, int counter){
      this.lock = obj; // monitor
      this.threadID = threadid; //id of thread  
      this.counter = counter;
      this.prev =threadid + 1;
  }

  public void run(){
      while(counter<100){
        synchronized(lock){ 
            if(counter == this.prev && this.threadID % 3 == this.threadID){
                System.out.println("T" + this.threadID + " = " + this.prev);
                this.prev = this.prev + 3;
            }
            counter++;
            lock.notifyAll();
            try{
                lock.wait();
            }catch(Exception e){
                e.printStackTrace();
            }
        }
      }
   }
}

public class ThreadMain {

    static volatile int counter = 1;
    public static void main(String args[]) throws InterruptedException{

       final Object lock = new Object();
       ThreadTask first = new ThreadTask(lock, 0, counter);
       ThreadTask second = new ThreadTask(lock, 1, counter);
       ThreadTask third = new ThreadTask(lock, 2, counter);
       Thread t1 = new Thread(first, "first");
       Thread t2 = new Thread(second, "second");
       Thread t3 = new Thread(third, "third");
       t1.start();
       t2.start();
       t3.start();
       t1.join();
       t2.join();
       t3.join();
   }
}