What is the purpose of using synchronized (Thread.currentThread()){...} in Java?

Question

I faced the following code in our project:

synchronized (Thread.currentThread()){     //some code } 

I don't understand the reason to use synchronized on currentThread.

Is there any difference between

synchronized (Thread.currentThread()){     //some code } 

and just

//some code 

Can you provide an example which shows the difference?

UPDATE

more in details this code as follows:

synchronized (Thread.currentThread()) {        Thread.currentThread().wait(timeInterval); } 

It looks like just Thread.sleep(timeInterval). Is it truth?

Answer 1

consider this

    Thread t = new Thread() {         public void run() { // A             synchronized (Thread.currentThread()) {                 System.out.println("A");                 try {                     Thread.sleep(5000);                 } catch (InterruptedException e) {                 }             }         }     };     t.start();     synchronized (t) { // B         System.out.println("B");         Thread.sleep(5000);     } 

blocks A and B cannot run simultaneously, so in the given test either "A" or "B" output will be delayed by 5 secs, which one will come first is undefined