thread-->CallableDemo

package thread;

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

/** Runnable是执行工作的独立任务，但是它不返回任何值，如果希望任务在完成时能够返回一个值，可以实现Callable接口 */
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 service = Executors.newCachedThreadPool();
        List<Future<String>> results = new ArrayList<Future<String>>();
        for (int i = 0; i < 10; i++)
            results.add(service.submit(new TaskWithResult(i)));
        for (Future<String> fs : results)
        {
            try
            {
                System.out.println(fs.get());
            }
            catch (InterruptedException e)
            {
                e.printStackTrace();
            }
            catch (ExecutionException e)
            {
                e.printStackTrace();
            }
            finally
            {
                service.shutdown();
            }
        }
    }
}