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This article focuses on "how to use java CountDownLatch thread counter", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let the editor take you to learn how to use java's CountDownLatch thread counter.

The concept of using CountDownLatch

The class countDownLatch causes one thread to wait for other threads to execute after each has finished executing.

CountDownLatch is implemented through a counter whose initial value is the number of threads. Every time a thread finishes executing, the value of the counter is-1. When the value of the counter is 0, all threads are finished, and then the thread waiting on the lock can resume work.

Working with scen

In some cases, due to the database table query is too slow, and can not be optimized in the database sql layer, then we need to use threads in the code to paging query data, multiple threads are completed after the data will be encapsulated into a list to return, then we need to ensure that all threads are completed before returning.

Use of CountDownLatch / / first create a thread counter construction parameter as the number of threads CountDownLatch countDownLatch = new CountDownLatch (3); / / create a result collection List list = new ArrayList (); / / Loop paging query for (int I = 1; I {/ / call query List list1 = mapper.find (I * 10,10); / / add the result to the collection list.addAll (list1) / / after execution, the thread counter-1 method countDownLatch.countDown ();} try {/ / the thread calling the await () method will be suspended and it will wait until the count value is 0 before continuing to execute countDownLatch.await (); System.out.println ("return data addition completed");} catch (Exception e) {e.printStackTrace () } in all methods / / countDownLatch classes of CountDownLatch, there is only one constructor count with the count value public CountDownLatch (int count) {}; / / the thread calling the await () method will be suspended and it will wait until the count value is 0 before continuing to execute public void await () throws InterruptedException {}; / / is similar to await (), except that it will continue to execute public boolean await (long timeout, TimeUnit unit) throws InterruptedException {} if the count value does not change to zero after a certain period of time. / / subtract the count value from 1public void countDown () {}; / / return the current count public long getCount () {}; / / return the counter identification and the current count public String toString () {}; at this point, I believe you have a deeper understanding of "how to use java CountDownLatch thread counter", might as well to actually do it! Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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