标签：data pre java out tor .sh 返回 int service
1.主线程等待法
2.使用Thread类的join()阻塞当前线程，等待子线程执行完毕
3.通过Callable接口实现：通过FutureTask Or线程池获取
public class CycleWait implements Runnable{ private String value; @Override public void run() { try { Thread.currentThread().sleep(5000); } catch (InterruptedException e) { e.printStackTrace(); } value = "we have data now"; } public static void main(String[] args) throws InterruptedException { CycleWait cw = new CycleWait(); Thread t = new Thread(cw); t.start(); while (cw.value == null){ Thread.currentThread().sleep(100); } System.out.println("value : " + cw.value); } }
2.使用Thread类的join()阻塞当前线程，等待子线程执行完毕
public class CycleWait implements Runnable{ private String value; @Override public void run() { try { Thread.currentThread().sleep(5000); } catch (InterruptedException e) { e.printStackTrace(); } value = "we have data now"; } public static void main(String[] args) throws InterruptedException { CycleWait cw = new CycleWait(); Thread t = new Thread(cw); t.start(); t.join(); System.out.println("value : " + cw.value); } }
缺点很明显，不够精准，只能等子线程结束才能继续主线程
（1）使用FutureTask获取返回值
public class MyCallable implements Callable<String> { @Override public String call() throws Exception{ String value="test"; System.out.println("Ready to work"); Thread.currentThread().sleep(5000); System.out.println("task done"); return value; } public static void main(String[] args) throws ExecutionException, InterruptedException { FutureTask<String> task = new FutureTask<String>(new MyCallable()); new Thread(task).start(); if(!task.isDone()){ System.out.println("task has not finished, please wait!"); } System.out.println("task return: " + task.get()); } }
（2）通过线程池获取返回值
public class MyCallable implements Callable<String> { @Override public String call() throws Exception{ String value="test"; System.out.println("Ready to work"); Thread.currentThread().sleep(5000); System.out.println("task done"); return value; } public static void main(String[] args) { ExecutorService newCachedThreadPool = Executors.newCachedThreadPool(); Future<String> future = newCachedThreadPool.submit(new MyCallable()); if(!future.isDone()){ System.out.println("task has not finished, please wait!"); } try { System.out.println(future.get()); } catch (Exception e) { e.printStackTrace(); }finally { newCachedThreadPool.shutdown(); } } }
Java多线程和并发（四），线程返回值获取方式和Callable接口
标签：data pre java out tor .sh 返回 int service
原文地址：https://www.cnblogs.com/xzmxddx/p/10362810.html
