从工作中返回值
import java.util.ArrayList;import java.util.concurrent.*;class TaskWithResult implements Callable<String> { //要想得到返回值能够实现Callable接口,类型参数是返回值的类型 private int id; public TaskWithResult(int id) { this.id = id; } @Override public String call() throws Exception { //实现call()办法，而不是run() return "result of TaskWithResult" + id; }}public class CallableDemo { public static void main(String[] args) { ExecutorService exec = Executors.newCachedThreadPool(); ArrayList<Future<String>> results = new ArrayList<>(); //submit办法会产生Future对象 for (int i = 0; i < 10; i++) { results.add(exec.submit(new TaskWithResult(i)));//必须应用ExectorService.submit()办法调用 } for (Future<String> fs : results) { try { System.out.println(fs.get()); //get()办法获取返回的后果， } catch (InterruptedException e) { System.out.println(e); return; } catch (ExecutionException e) { System.out.println(e); }finally { exec.shutdown(); //敞开 } } }}
- 能够应用Futrue对象的isDone()办法来查问Futrue是否已实现
- 也能够间接调用get()，get()办法会等到后果就绪后调用
优先级
import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class SimplePriorities implements Runnable{ private int countDown = 5; private volatile double d; private int priority; public SimplePriorities(int priority) { this.priority = priority; } public String toString(){ return Thread.currentThread()+"优先级："+priority + "计数" + ":"+countDown; } @Override public void run() { Thread.currentThread().setPriority(priority); while (true) { for (int i = 0; i < 100000; i++) { d += (Math.PI + Math.E) / (double) i; if (i%1000==0) Thread.yield(); } System.out.println(this); if (--countDown==0) return; } } public static void main(String[] args) { ExecutorService exec = Executors.newCachedThreadPool(); for (int i = 0; i < 5; i++) { exec.execute(new SimplePriorities(Thread.MIN_PRIORITY)); } exec.execute(new SimplePriorities(Thread.MAX_PRIORITY)); exec.shutdown(); }}