Detailed explanation of several states of java threads

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Threads can have six states:

　1.New (newly created)

　2.Runnable（runnable）（run）

　3.Blocked（blocked）

　4.Waiting（ Waiting)

5.Timed waiting

6.Terminated

Newly created thread:

When using the new operator to create a new thread, such as new Thread(r), the thread has not started running yet, and its current The status is new, and there is still some basic work to be done before the thread can run.

Runnable thread:

Once the thread calls the start method, the thread is in the runnable state. The thread in this state may or may not be running (that is, the running thread in the Java specification is still in the runnable state). It also returns to the runnable state after the thread is running or after returning from the blocking, waiting, or sleeping state.

Blocked thread:

In this state, it is a scenario where multiple threads have synchronized operations, such as waiting for another thread The execution of the synchronized block is released, or someone else calls the wait() method in the reentrant synchronized block, that is, the thread is waiting to enter the critical section.

Waiting thread:

This state means that after the thread owns a certain lock, it calls its wait method, or the thread calls the join method to join another thread. The thread is waiting for the execution of the thread it joins to end. Here we need to distinguish the difference between blocking state and waiting state. One is waiting to enter outside the critical point, and the other is waiting inside the critical point.

Timing waiting thread:

When a thread calls a method with a timeout parameter, it will cause the thread to enter a timing waiting state. Methods with supermarket parameters include Thread.sleep , Object.wait, Thread.join, Lock.tryLock and the timing version of Condition.await.

Terminated thread:

　1) The thread dies naturally because the run method exits normally.

　2) Unexpected death because an uncaught exception terminated the run method.

Conversion between thread states:

　　　　　　

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