Java并发编程--三个线程顺序打印ABC

 

three Thread A, B C;
Thread A print "A"
Thread B print "B"
Thread C print "C"
like this ABC...ABC(Total 10 ABC)

 

代码实现：

/** * */ package concurrent.sample.print; import java.util.concurrent.atomic.AtomicReference; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; /** * three Thread A, B C; * Thread A print "A" * Thread B print "B" * Thread C print "C" * * like this ABC...ABC(Total 10 ABC) * * 小结： * 利用lock+cas对简单实现（synchronized+volatile）进行提升性能, 并简化编程 * 使用while(condition) { lock.wait(); }+lockfree算法 提升并发调度健壮性 * * @author yangwm Jul 29, 2010 11:23:32 AM */ public class SimpleCasPrintABC { public static void main(String[] args) { new Thread(new PrintRun(), "A").start(); new Thread(new PrintRun(), "B").start(); new Thread(new PrintRun(), "C").start(); } /** mutex */ private static final Lock PRINT_LOCK = new ReentrantLock(); /** mutex for waiting print */ private static final Condition PRINT_CONDITION = PRINT_LOCK.newCondition(); /** total print times */ private static final int TOTAL_PRINT_COUNT = 10; /** semaphore */ private static AtomicReference<String> semaphore = new AtomicReference<String>("A"); public static boolean nextSemaphore() { boolean result = false; String semaphoreValue = semaphore.get(); if("A".equals(semaphoreValue)) { result = semaphore.compareAndSet(semaphoreValue, "B"); } else if("B".equals(semaphoreValue)) { result = semaphore.compareAndSet(semaphoreValue, "C"); } else if("C".equals(semaphoreValue)) { result = semaphore.compareAndSet(semaphoreValue, "A"); } return result; } /** * Thread print current thread name */ private static class PrintRun implements Runnable { /** print times */ private int printCount = TOTAL_PRINT_COUNT; @Override public void run() { while (printCount > 0) { String threadName = Thread.currentThread().getName(); PRINT_LOCK.lock(); try { try { while(!semaphore.get().equals(threadName)) { PRINT_CONDITION.await(); } } catch (InterruptedException e) { System.err.println(threadName + " Print InterruptedException"); PRINT_CONDITION.signalAll(); } } finally { PRINT_LOCK.unlock(); } /* do print */ System.out.print(threadName); for(;;) { if (nextSemaphore()) { break; } } printCount--; PRINT_LOCK.lock(); try { PRINT_CONDITION.signalAll(); } finally { PRINT_LOCK.unlock(); } } } } }

 

输出： ABCABCABCABCABCABCABCABCABCABC