CallableとFutureによるスレッドの作成

  ：
public class CallableThreadTest implements Callable {
    public static void main(String[] args)  
    {  
        CallableThreadTest ctt = new CallableThreadTest();  
        FutureTask ft = new FutureTask<>(ctt);  
        for(int i = 0;i < 100;i++)  
        {  
            System.out.println(Thread.currentThread().getName()+"      i  "+i);  
            if(i==20)  
            {  
                new Thread(ft,"       ").start();  
            }  
        }  
        try  
        {  
            System.out.println("       ："+ft.get());  
        } catch (InterruptedException e)  
        {  
            e.printStackTrace();  
        } catch (ExecutionException e)  
        {  
            e.printStackTrace();  
        }  
  
    }
    @Override  
    public Integer call() throws Exception  
    {  
        int i = 0;  
        for(;i<100;i++)  
        {  
            System.out.println(Thread.currentThread().getName()+" "+i);  
        }  
        return i;  
    }  
}

   ：
public class Test1 implements Callable{


    public String call() throws Exception {
        System.out.print("  1："+Thread.currentThread().getName());
        return null;
    }


    public static void main(String [] args){
        FutureTask b =new FutureTask(new Test1());
        Thread a =new Thread(b);
        a.start();
        System.out.println("  2："+Thread.currentThread().getName());
    }