Java中创建线程的几种方式

盘点一下Java中创建线程的几种方式

一、继承Thread类，重写run()方法

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public class MyThread extends Thread {       @Override     public void run() {         System.out.println("my thread start " + Thread.currentThread().getName());     }       public static void main(String[] args) {         System.out.println("main thread start "+Thread.currentThread().getName());         MyThread myThread = new MyThread();         myThread.start();     } }

二、实现Runnable接口，并重写run()方法

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public class MyThreadRunnable implements Runnable {       @Override     public void run() {         System.out.println("my thread start " + Thread.currentThread().getName());     }       public static void main(String[] args) {         System.out.println("main thread start " + Thread.currentThread().getName());         MyThreadRunnable myThreadRunnable = new MyThreadRunnable();         Thread thread = new Thread(myThreadRunnable);         thread.start();     } }

三、实现Callable接口，并重写call()方法

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public class MyThreadCallable implements Callable<Integer> {     @Override     public Integer call() throws Exception {         System.out.println("my thread start " + Thread.currentThread().getName());         Integer ret = 0;         for (int i = 0; i < 10; i++) {             ret += i;         }         return ret;     }       public static void main(String[] args) throws ExecutionException, InterruptedException {         MyThreadCallable myThreadCallable = new MyThreadCallable();         FutureTask<Integer> futureTask = new FutureTask<>(myThreadCallable);         Thread thread = new Thread(futureTask, "A");         thread.start();         int ret = futureTask.get();         System.out.println("main thread ret = " + ret + " " + Thread.currentThread().getName());     } }

综上，类图关系如下：

四、CompletableFuture

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public class CompletableFutureDemo {     private static ExecutorService threadPool = new ThreadPoolExecutor(             2,             5,             1L,             TimeUnit.SECONDS,             new LinkedBlockingDeque<>(3),             Executors.defaultThreadFactory(),             new ThreadPoolExecutor.CallerRunsPolicy()     );       public static void main(String[] args) {         CompletableFuture future1 = CompletableFuture.runAsync(() -> {             System.out.println("执行没有返回值的任务");         });         CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> {             System.out.println("执行有返回值的任务");             return "abc";         });         CompletableFuture<String> future3 = CompletableFuture.supplyAsync(() -> {             System.out.println("线程池执行有返回值的任务");             return "123";         }, threadPool);         future1.join();         System.out.println(future2.join());         System.out.println(future3);         threadPool.shutdown();     } }