有三个线程T1,T2,T3,如何保证顺序执行

文章目录

1. 使用 join 方法
2. 使用 CountDownLatch
3. 使用 Semaphore
4. 使用 ReentrantLock 和 Condition
5. 使用 BlockingQueue

1. 使用 join 方法

通过使用 Thread.join 方法，可以确保一个线程在另一个线程完成后再开始执行。

public class JoinExample {public static void main(String[] args) {Thread t1 = new Thread(() -> {System.out.println("T1 is running");});Thread t2 = new Thread(() -> {try {t1.join();System.out.println("T2 is running");} catch (InterruptedException e) {e.printStackTrace();}});Thread t3 = new Thread(() -> {try {t2.join();System.out.println("T3 is running");} catch (InterruptedException e) {e.printStackTrace();}});t1.start();t2.start();t3.start();}
}

2. 使用 CountDownLatch

通过使用 CountDownLatch，可以确保线程按顺序执行。

import java.util.concurrent.CountDownLatch;public class CountDownLatchExample {public static void main(String[] args) {CountDownLatch latch1 = new CountDownLatch(1);CountDownLatch latch2 = new CountDownLatch(1);Thread t1 = new Thread(() -> {System.out.println("T1 is running");latch1.countDown();});Thread t2 = new Thread(() -> {try {latch1.await();System.out.println("T2 is running");latch2.countDown();} catch (InterruptedException e) {e.printStackTrace();}});Thread t3 = new Thread(() -> {try {latch2.await();System.out.println("T3 is running");} catch (InterruptedException e) {e.printStackTrace();}});t1.start();t2.start();t3.start();}
}

3. 使用 Semaphore

使用 Semaphore 可以控制线程的执行顺序。

import java.util.concurrent.Semaphore;public class SemaphoreExample {public static void main(String[] args) {Semaphore sem1 = new Semaphore(0);Semaphore sem2 = new Semaphore(0);Thread t1 = new Thread(() -> {System.out.println("T1 is running");sem1.release();});Thread t2 = new Thread(() -> {try {sem1.acquire();System.out.println("T2 is running");sem2.release();} catch (InterruptedException e) {e.printStackTrace();}});Thread t3 = new Thread(() -> {try {sem2.acquire();System.out.println("T3 is running");} catch (InterruptedException e) {e.printStackTrace();}});t1.start();t2.start();t3.start();}
}

4. 使用 ReentrantLock 和 Condition

使用 ReentrantLock 和 Condition 可以更细粒度地控制线程的执行顺序。

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;public class LockConditionExample {private static final Lock lock = new ReentrantLock();private static final Condition condition1 = lock.newCondition();private static final Condition condition2 = lock.newCondition();private static boolean t1Finished = false;private static boolean t2Finished = false;public static void main(String[] args) {Thread t1 = new Thread(() -> {lock.lock();try {System.out.println("T1 is running");t1Finished = true;condition1.signal();} finally {lock.unlock();}});Thread t2 = new Thread(() -> {lock.lock();try {while (!t1Finished) {condition1.await();}System.out.println("T2 is running");t2Finished = true;condition2.signal();} catch (InterruptedException e) {e.printStackTrace();} finally {lock.unlock();}});Thread t3 = new Thread(() -> {lock.lock();try {while (!t2Finished) {condition2.await();}System.out.println("T3 is running");} catch (InterruptedException e) {e.printStackTrace();} finally {lock.unlock();}});t1.start();t2.start();t3.start();}
}

5. 使用 BlockingQueue

通过使用 BlockingQueue 可以控制线程的执行顺序。

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;public class BlockingQueueExample {public static void main(String[] args) {BlockingQueue<String> queue1 = new ArrayBlockingQueue<>(1);BlockingQueue<String> queue2 = new ArrayBlockingQueue<>(1);Thread t1 = new Thread(() -> {System.out.println("T1 is running");try {queue1.put("T1 done");} catch (InterruptedException e) {e.printStackTrace();}});Thread t2 = new Thread(() -> {try {queue1.take();System.out.println("T2 is running");queue2.put("T2 done");} catch (InterruptedException e) {e.printStackTrace();}});Thread t3 = new Thread(() -> {try {queue2.take();System.out.println("T3 is running");} catch (InterruptedException e) {e.printStackTrace();}});t1.start();t2.start();t3.start();}
}