使用ExecutorService或类似于按顺序完成的队列任务?

您可以使用单个线程执行器。下面的服务将与主线程并行运行 e2 将依次运行。

ExecutorService e1 = Executors.newSingleThreadExecutor();
ExecutorService e2 = Executors.newSingleThreadExecutor();
e1.execute( new ExpressTask() );
e2.execute( new SequentialTask("Part-One"));
e2.execute( new SequentialTask("Part-Two"));
e2.execute( new SequentialTask("Part-Three"));
e1.shutdown();
e2.shutdown();

只需运行一个线程:

new Thread() {
    public void run() {
       task1.run();
       task2.run();
       task3.run();
    }
}.start();