作用:获得线程执行完的结果
package ThreadPractice;
import java.util.concurrent.*;
/**
* Created by qiaorenjie on 2018/3/28.
*/
public class CallableAndFuture {
public static void main(String[] args) {
// 1.提交一条线程
ExecutorService threadPool = Executors.newSingleThreadExecutor();
Future<String> future =
threadPool.submit(
new Callable<String>() { // 注意Callable与Future类型必须一致用泛型
@Override // 注意new的是callable
public String call() throws Exception { // 不再是runnable中的run而是callable中的call
Thread.sleep(2000);
return "Hello";
}
}
);
System.out.println("等待结果");
try {
System.out.println("拿到结果:" + future.get());
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
//2.提交一组线程
ExecutorService threadPool2 = Executors.newFixedThreadPool(10);
CompletionService<Integer> completionService = new ExecutorCompletionService<Integer>(threadPool2);
for (int i = 1; i <= 10; i++) {
final int seq = i;
completionService.submit(new Callable<Integer>() {
@Override
public Integer call() throws Exception {
Thread.sleep(new Random().nextInt(5000));
return seq;
}
});
}
for (int i = 0; i < 10; i++) {
try {
System.out.println(completionService.take().get());
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
}
=====console======
等待结果
拿到结果:Hello
由此,可以看出Callable接口方法下的call用于写回调结果,new的callable必须要重写call()方法,而call()方法是需要return返回的,在ruturn中写需要回调的信息,再通过Future的get()方法获取到回调的结果数据
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