IllegalMonitorStateException on wait() call

Question

I am using multi-threading in java for my program. I have run thread successfully but when I am using Thread.wait(), it is throwing java.lang.IllegalMonit

Answer 1

I received a IllegalMonitorStateException while trying to wake up a thread in / from a different class / thread. In java 8 you can use the lock features of the new Concurrency API instead of synchronized functions.

I was already storing objects for asynchronous websocket transactions in a WeakHashMap. The solution in my case was to also store a lock object in a ConcurrentHashMap for synchronous replies. Note the condition.await (not .wait).

To handle the multi threading I used a Executors.newCachedThreadPool() to create a thread pool.