CyclicBarrier and CountDownLatch are located under the package java.util.concurrent
A, CountDownLatch usage
CountDownLatch class only provides a constructor:
public CountDownLatch (int count) {} ; // count value of the count parameter is
then the following three methods are the most important class CountDownLatch Method:
public void await () throws InterruptedException { }; // thread calls the await () method will be suspended, it waits until the count value of zero before continuing execution
public boolean await (long timeout, TimeUnit unit) throws InterruptedException {}; // and the await () is similar, except to wait for a certain time after the count value becomes 0, then it will not proceed to
public void countDown () {}; // the count value by one
A CountDownLatch, a synchronization aid, until a set of operations is performed in other threads, which allows one or more threads to wait.
下面举个例子说明：
package main.java.CountDownLatch;
import java.util.concurrent.CountDownLatch;
/**
* PROJECT_NAME:downLoad
* Author:lucaifang
* Date:2016/3/18
*/
public class countDownlatchTest {
public static void main(String[] args) throws InterruptedException {
CountDownLatch countDownLatch = new CountDownLatch(5);
for(int i=0;i<5;i++){
new Thread(new readNum(i,countDownLatch)).start();
}
countDownLatch.await();
System.out.println("线程执行结束。。。。");
}
static class readNum implements Runnable{
private int id;
a CountDownLatch LATCH Private;
public readNum (int ID, a CountDownLatch LATCH) {
this.id ID =;
this.latch = LATCH;
}
@Override
public void RUN () {
the synchronized (the this) {
System.out.println ( "ID:" the above mentioned id +);
latch.countDown ();
System.out.println ( "thread group task" + id + "end, other tasks continue");
}
}
}
}
Output:
the above mentioned id: 1
thread group Task 1 over, other tasks continue
id: 0
thread group task 0 ends, the other tasks continue
id: 2
Thread Group Task 2 over, other tasks continue
id: 3
thread group task 3 over, other tasks continue
id: 4
end task 4 thread group, other tasks continue
thread execution ends. . . .
Thread countDown () after, will continue to perform its task, but in the end all will CyclicBarrier threaded tasks, will carry out follow-up tasks, specific examples can be seen below.
Two, CyclicBarrier usage
CyclicBarrier provides two constructors:
CyclicBarrier public (int parties, Runnable barrierAction) {
}
public CyclicBarrier (int parties) {
}
parameter parties refers to how many threads to make or tasks waiting to barrier state; parameter barrierAction content when these threads have reached the barrier state will perform.
CyclicBarrier The most important way is to await method
public int await () throws InterruptedException, BrokenBarrierException {}; // suspends the current thread, until all threads have reached the barrier state again while performing subsequent task;
public int the await (Long timeout, TimeUnit Unit) throws InterruptedException, a BrokenBarrierException, a TimeoutException {} ; // let these threads to wait until a certain time, if there is no thread to reach the barrier state to directly thread reaches the barrier to perform follow-up tasks
举例说明
package main.java.countOff;
import java.util.concurrent.CyclicBarrier;
/**
* PROJECT_NAME:downLoad
* Author:lucaifang
* Date:2016/3/18
*/
public class cyclicBarrierTest {
public static void main(String[] args) throws InterruptedException {
CyclicBarrier cyclicBarrier = new CyclicBarrier(5, new Runnable() {
@Override
public void run() {
System.out.println("线程组执行结束");
}
});
for (int i = 0; i < 5; i++) {
new Thread(new readNum(i,cyclicBarrier)).start();
}
//CyclicBarrier 可以重复利用，
// 这个是CountDownLatch做不到的
// for (int i = 11; i < 16; i++) {
// new Thread(new readNum(i,cyclicBarrier)).start();
// }
}
static class readNum implements Runnable{
private int id;
private CyclicBarrier cyc;
public readNum(int id,CyclicBarrier cyc){
this.id = id;
this.cyc = cyc;
}
@Override
public void run() {
synchronized (this){
System.out.println("id:"+id);
try {
cyc.await();
System.out.println ( "thread group task" + id + "end, continue other tasks");
} the catch (Exception E) {
e.printStackTrace ();
}
}
}
}
}
Output:
the above mentioned id: 1
the above mentioned id: 2
the above mentioned id: 4
the above mentioned id: 0
the above mentioned id: 3
thread group to perform the end of
the thread group task 3 over, other tasks continue
the thread group Task 1 over, other tasks continue to
the end of the thread group Task 4, other tasks continue
thread 0 end group task, other tasks continue to
thread groups task 2 over, other tasks continue
