Java文档中ExecutorService方法shutdown（）的矛盾

Question

Here is the first line in the javadoc :

Initiates an orderly shutdown in which previously submitted tasks are executed , but no new tasks will be accepted. Invocation has no additional effect if already shut down.

And here is the second line right beneath the previous one:

This method does not wait for previously submitted tasks to complete execution . Use awaitTermination to do that.

So which is it? Does shutdown() wait for previously submitted tasks to be executed before shutting down or doesn't it?

Answer 1

There is no contradiction. The method just tells the executor "please don't accept new tasks" and returns immediately. The thread which asked for shutdown can then keep doing something else, while the executor keeps executing the submitted tasks, in parallel.