Synchronizing Threads in java

Synchronizing Threads in java

Synchronizing Threads 



  • In Java, every object has a lock.
  •  To obtain the lock, you must synchronize with the object. 
  • The simplest way to use synchronization is by declaring one or more methods to be synchronized 
  • When a synchronized method is invoked, the calling thread attempts to obtain the lock on the object.
  • if it cannot obtain the lock, the thread goes to sleep until the lock becomes available 
  • Once the lock is obtained, no other thread can obtain the lock until it is released. ie, the synchronized method terminates 
  • When a thread is within a synchronized method, it knows that no other synchronized method can be invoked by any other thread 
  • Therefore, it is within synchronized methods that critical data is updated

class Parent
{
 public void display(String msg)
 {
  System.out.print ("["+msg);
  try
  {
   Thread.sleep(1000);
  }
  catch(InterruptedException e)
  {
   e.printStackTrace();
  }
  System.out.println ("]");
 }
}

class Child extends Thread
{
 String msg;  
 First fobj;
 Child (First fp,String str)
 {
  fobj = fp;
  msg = str;
  start();
 }
 public void run()
 {
  synchronized(fobj)       //Synchronized block
  {
   fobj.display(msg);
  }
 }
}

public class Syncro
{
 public static void main (String[] args) 
 {
  Parent fnew = new Parent();
  Child ss = new Child(fnew, "welcome");
  Child ss1= new Child (fnew,"new");
  Child ss2 = new Child(fnew, "programmer");
 }
}