multithreading - 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