public class AsyncMethodInvocation {
    /**
     * Async Method Invocation【非同步方法呼叫】
     */
    @Test
    public void all() throws InterruptedException, ExecutionException {
        final String result = "async method invocation";
        // 1）可執行的非同步任務呢
        final Callable<String> callable = ()->{
            // 2）非同步任務的結果
            return result;
        };
        // 3）執行非同步任務的執行緒池
        final ExecutorService executorService = Executors.newFixedThreadPool(1);
        final Future<String> future = executorService.submit(callable);
        // 4）可在將來讀取非同步任務的計算結果
        assertEquals(result, future.get());
        executorService.awaitTermination(2, TimeUnit.SECONDS);
    }
}