Trying to get a Thread to wait for an event to be received with the JDA, but I can't escape an IllegalMonitorStateException [duplicate]

I'm working on a small game to be played through discord by me and some friends.

My code should theoretically work, but for some reason I can't escape the IllegalMonitorStateException "current Thread is not owner" caused by the wait() method below.

public void waitForMethod () { Thread thread = new Thread() { @Override public void run () { synchronized(lock) { while (true) { if (methodDone) { methodDone = false; channel.sendMessage("methodDone = true").queue(); break; } else { channel.sendMessage("methodDone = false").queue(); try { wait(); channel.sendMessage("successfully notified.").queue(); } catch (InterruptedException e) {} } } } } }; thread.run(); channel.sendMessage("exited Thread.").queue(); } 

So far, I've been able to get all but the "successfully notified" message and "methodDone = true" to send, obviously because as soon as it calls "wait();" it raises the IllegelMonitorStateException "current Thread is not owner."

Below is the code that relies on the "waitForMethod()" method.

@Override public void onMessageReceived (MessageReceivedEvent event) { synchronized(lock) { handleEvent(event); lock.notify(); } } 

To be clear, waitForMethod is called by a class that represents the game's loop, and is simply meant to make the game loop pause until a variable has been changed by the "handleEvent()" method to true, in which case it should continue the game's loop.

I'm basically just looking for a way to pause a section of code until another section of code tells it to unpause.

I tried using the EventWaiter, but I couldn't find a way to properly set up the dependencies or import it, so I kind of gave up and went with something I'm at least somewhat familiar with.