How to organize a series of running tasks?

Question

The task is as follows.

There is a queue of tasks. It is necessary to create a thread that periodically these problems will come.

comes to mind is the following mechanism. Create a class that inherits from Thread and a run method to do something like this:

while (! isInterrupted ()) {
    while (executedTask! = null) {
       // Execute task
       // Push callback about successfully processed task
       executedTask == null;
    }
}

But looking at the code, intuition suggests that someone is me "hands behind such whacks" :)

Therefore, I want to ask how would be better to implement this task. It is no code, just words. I would be grateful for links to examples.

        ------------------     -------------------
        |   TaskHolder   |     |   WorkerThread  |            
        ------------------     -------------------
                |                        |
         task   |      execute           |
        ------->|----------------------->|
         task#2 |              hard-time task worked
        ------->|queue task until current|
                |task is processed       |
         task#3 |                        |
        ------->|queue task until current|
                |task is processed       |
         task#4 |                        |
        ------->|queue task until current|
                |task is processed       |
         task#5 |                        |
        ------->|queue task until current|
                |task is processed       |
         task#6 |                        |
        ------->|queue task until current|
                |task is processed       |
                |                        |
                |                        |
                |                 task finished
                |    return result       |
                |<-----------------------|
                |                        |
                |pop task#2 from queue   |
                |      execute task#2    |
                |----------------------->|
                       .   .    .

Answer 1

You should create an ExecutorService with only one thread like.

ExecutorService executor = Executors.newFixedThreadPool(1);

And then when you want to add a task to the queue create a new runnable and submit it.

executor.submit(new Runnable() {
    public void run() {
            //your code here
    }
});

A single threaded ExecutorService will only run one task at a time and will queue up new tasks that you submit to it and run them in the order you submit them.

As a bonus this pattern can be particularly useful if you have a multi threaded environment and want to avoid complex synchronization and locking issues.