The States a Thread Moves Through, and Who Moves It

A thread dump on a stuck service shows forty threads and a word beside each one. Reading those words is most of diagnosing a hang, and there are only a handful of them.

A thread moves from new to terminated and never goes back

What each state means in a thread dump
State	Means	Waiting for
`NEW`	Created, never started	Nothing — nobody has called `start()`
`RUNNABLE`	Able to run	A processor, or the operating system
`BLOCKED`	Wants a lock somebody else holds	That lock
`WAITING`	Asked to be woken later	Another thread, with no deadline
`TIMED_WAITING`	The same, with a deadline	Another thread, or the clock
`TERMINATED`	Its `run` method has returned	Nothing; it is finished

The arrow that does not exist is the one from TERMINATED back to RUNNABLE. A thread that has finished is finished, and calling start() on it a second time throws IllegalThreadStateException.

So a Thread object is not a worker you hand jobs to. It is one job, run once, and the thing that lets you hand jobs to a reusable worker is a pool.