Does Java provide an ExecutorService which allows a worker to execute on the same thread?

It sounds like what you actually want are actors . Put simply, an actor is an object that runs in a single thread and has a "mailbox" of tasks that it's responsible for processing sequentially. Akka seems to be the current leading library/framework providing actors on the JVM.

Take a look over there. There's also another SO answer that lists several alternatives for actors in Java.

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