Thread. Sleep and timeunit SECONDS. The difference between sleep

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        When the thread needs to sleep for a period of time , have access to Thread.sleep/TimeUnit.SECONDS.sleep Make the current thread pause execution , Both can be achieved , No difference . Wait until the sleep time ends , The thread can continue to execute .

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        Thread.sleep() yes java.lang Class method under package , The received parameter unit is milliseconds , If you need to pause the current thread for seconds , minute , Hours, etc , It needs to be converted manually according to the millisecond unit ;TimeUnit.SECONDS.sleep() yes java.util.concurrent Class method under package , The bottom call is still Thread.sleep(), It's right Thread.sleep() Packaging of methods , More time unit conversion and verification .

    public void sleep(long timeout) throws InterruptedException {
        if (timeout > 0) {
            long ms = toMillis(timeout);
            int ns = excessNanos(timeout, ms);
            Thread.sleep(ms, ns);
        }
    }

          When TimeUnit It's followed by SECONDS, be TimeUnit.SECONDS.sleep(long time) Means to pause the thread time Second , The same can be TimeUnit.MINUTES.sleep(); TimeUnit.HOURS.sleep(); TimeUnit.DAYS.sleep();

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        Thread.sleep() You can make the current thread sleep for a period of time , But the lock held in this thread will not be released , Just temporarily give up the right of execution of time , Do not participate during cpu The scheduling . When sleep time is up , The thread will be in a ready state , To be obtained cpu After the scheduling time slice , Will continue to run .

        about wait() Method , Will release the synchronization resource lock , It is convenient for the thread waiting for the resource to get the resource and then run , Only other threads call notify()/notifyall() After method , The thread will release the waiting state , So as to participate in the competition to synchronize resource locks .（ Be careful ：wait() yes Object Methods in class ）

        If you want a thread A The logic inside needs to be in the thread B Execute after the logic execution in , have access to Thread Class join(long time) Method , It can be set flexibly time value .