連線：https://www.cnblogs.com/dennyzhangdd/p/7010972.html

public class AsyncDemo {
    public static void main(String[] args) throws Exception{
        ExecutorService executorService = Executors.newFixedThreadPool(10);
        Test1 t1 = new Test1();
        FutureTask<Integer> ft1 = new FutureTask<>(t1);
        executorService.submit(ft1);
        //會阻塞主執行緒
 
        //System.out.println("r1 = " +ft1.get());
        //jdk1.8的實現方式
Test3 test3 = new Test3();
        CompletableFuture<Integer> future1 = CompletableFuture.supplyAsync(test3, executorService);
        //採用lambada的實現方式，不會阻塞主執行緒
future1.thenAccept(e -> System.out.println(e + " ok"));
        System.out
 
.println("main thread is running");

        //System.out.println("r1 = " +ft1.get());
Test2 t2 = new Test2();
        FutureTask<Integer> ft2 = new FutureTask<>(t2);
        executorService.submit(ft2);
        System.out.println("r2 = " +ft2.get());
        executorService.shutdown();
    }
}

class 
 
Test1 implements Callable<Integer>{
    @Override
public Integer call() throws Exception {
        Integer i = new Integer(1000);
        System.out.println("sleep before i = "+i);
        Thread.sleep(5000);
        i = i + 5000;
        System.out.println("sleep after i = "+i);
        return i;
    }
}
class Test2 implements Callable<Integer>{
    @Override
public Integer call() throws Exception {
        Integer i = new Integer(2000);
        System.out.println("sleep before i2 = "+i);
        i = i + 5000;
        System.out.println("sleep after i2 = "+i);
        return i;
    }
}

class Test3 implements Supplier<Integer>{
    @Override
public Integer get()  {
        Integer i = new Integer(3000);
        System.out.println("sleep before i3 = "+i);

        try {
            Thread.sleep(8000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        i = i + 8000;
        System.out.println("sleep after i3 = "+i);
        return i;
    }
}