java多线程之从任务中获取返回值

package wzh.test;

import java.util.ArrayList;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

class TaskWithResult implements Callable<String>{
    private int id;
    public TaskWithResult(int id){
        this.id=id;
    }
    @Override
    public String call() throws Exception {
        return "result of TaskWithResult "+id;
    }
}

public class CallableDemo {
    public static void main(String[] args) {
        ExecutorService exec=Executors.newCachedThreadPool();
        ArrayList<Future<String>> results=new ArrayList<Future<String>>();
        for (int i = 0; i < 10; i++) {
            results.add(exec.submit(new TaskWithResult(i)));
        }
        for (Future<String> future : results) {
            try {
                System.out.println(future.get());
            } catch (Exception e) {
                e.printStackTrace();
            }
            finally{
                exec.shutdown();
            }
        }
    }
}