Notify not getting the thread out of wait state

Question

I am trying to use 2 threads. 1 thread prints only odd number and the other thread prints only even number and It has to be an alternative operation.

Eg:

Answer 1

Problem is that in one case you are taking lock on Thread t [synchronized (t) ] while in other case you are taking lock on TheadA object itself [synchronized(this)].

If you want threads to talk to each other then both should take lock on same object only then wait notify will work as you expect.

Edit:

There is another problem in your program, you are not using any variable to coordinate between 2 threads. SO you may see output like this 2,1,4,3...so on. Point is threads will work alternately but not in sequence. So you should share a single variable between 2 threads which should be incremented. Second issue is you are not taking care of spurious wake up calls [read some docs on this], you should always have wait called inside a while loop.