Advantages and disadvantages among Timer, ScheduledExecutorService, Thread

Question

Hi, what are the exact advantages and disadvantages among using Timer, using ScheduledExecutorService and just using Thread (Thread.sleep(...))?
For the simple task which needs to poll some values by some interval (the interval is not supposed very accurate, maybe about 5 seconds just ok), is it ok for just using Thread, like:
run() {
  while(isRunning) {
     Thread.sleep(5000);
     //do something
}?

Answer 1

jiangyc wrote:
Why using Timer and TimerTask is simpler and better than using Thread directly? Because it handles the rote stuff that's not directly part of your application. Ideally, your code should just be the marginal stuff that's specific to your app; anything else should be in the library you use. The less code the better.
I feel just using Thread doesn't make my code hard to maintain and by far I don't find any performance issue raised by using Thread (in our swing application, there are maybe less than 10 Thread objects which take care of the different polling tasks). It's not a performance issue; it's a code management issue. (Although the chances are good that Timer will have been well-tuned.) The less code you have, the less code you have to wade through to fix bugs, make changes, etc. This might not seem like much when it's a small program, but it adds up. In a business environment where you have huge codebases worked on by dozens of people (many of whom don't work there anymore) it becomes really important to only write what you have to and no more. Maybe if you're doing a small project it's not important, but keeping your code clean a good habit to get into.
And I wonder the base implementation of Timer and TimerTask is not using Thread?Of course it is. That's not the point. The point is that it keeps your code cleaner.
When you use Thread directly, probably the only part that's directly relevant to your program (as opposed to any other program that uses Thread) is the value you're sticking in Thread.sleep() -- the delay. You specify that in the schedule() call to the Timer.
If you keep your use of Thread minimal, then it might not be much bigger than using Timer/TimerTask, but the latter does more, including stuff you'll probably need to add (like ways to cancel the task).
Also, when you do this using Thread, you're exposing the implementation, but when you use Timer.schedule, you're exposing the intent. The latter makes for clearer code.