Thread five states (thread life cycle)

There are four ways to create threads code : Four ways to create threads _java-zh The blog of -CSDN Blog

1、 New state

When the current object is created , Before starting ( There is no call start Method ), such as Thread t = new Thread();

2、 Ready state

Ready to start , It's not implemented , Express call start After method , Not obtained cpu resources

3、 Running state

Currently in progress to get cpu After resources

4、 Death state :

When the running thread executes all the code logic normally or the program ends due to abnormal conditions, it is called dead state

5、 Blocked state

While the program is running , Something happened , This causes the current thread to fail to execute smoothly , It's going to be blocked , Into a blocked state
After the cause is eliminated , All blocking queues It will enter the ready state again , Grab at random cpu resources , Waiting for execution

Be careful

Why we call start() Method run() Method , Why can't we call it directly run() Method ？

new One Thread, The thread has entered a new state . call start() Method , Starts a thread and puts it in a ready state , When it's assigned to a timeslice, it's ready to run . start() Will perform the corresponding preparatory work of the thread , And then automatically run() Contents of the method , This is real multithreading .

And direct execution run() Method , Will be able to run Method as one main Common methods under thread to execute , It does not execute in a thread , So it's not multithreading .

summary ： call start Method to start a thread and make it ready , and run It's just thread A normal method call of , Or in the main thread .