Java 基于信号量线程的许可证

Question

I want to block threads with Semaphore (or alternative) . But same thread should not acquire multiple permit. For example:

import java.util.concurrent.Semaphore;

public class ConcurencyTest {

    public static void main(String[] args) throws InterruptedException {
        new ConcurencyTest().testSync(3);
        System.out.println("testSync finished");
        new ConcurencyTest().testSemaphore();
        System.out.println("testSemaphore finished");
    }

    public void testSemaphore() throws InterruptedException {
        final Semaphore s = new Semaphore(2);
        for (int i = 0; i < 10; i++) {
            s.acquire();
            System.out.println(i);
        }
    }

    public synchronized void testSync(int i) {
        if (i == 0) return;
        System.out.println(i);
        testSync(i - 1);
    }

}

Output is:

3
2
1
testSync finished
0
1
--just waiting

Is there any alternative of Semaphore for continue at --just waiting row like synchronized .

Answer 1

I guess you want a ReentrantLock , but that is just a guess since the question is bit unclear.