Create a Job Queue or Task Controller and dynamically add task to it in Java

Question

I want to create a job queue to execute multiple tasks. but, my requirement is I should be able to add tasks to that job queue at any time and all those tasks should be executed sequentially. I searched for some solutions on the internet and found these two links:

1. Java Thread Pool Executor Example

2. Java Executor Framework Tutorial and Best Practices

But I can't use both of these solutions. Because after starting the ExecutorService I can't add a new task to the service. Because we know that It may throw InterruptedException or ConcurrentModificationException.

Answer 1

You can use a BlockingQueue to keep waiting in a separate thread until one or more Runnable show up.

public class Mainer {
    private static final BlockingQueue<Runnable> queue = new ArrayBlockingQueue<>(15);

    public static void main(String[] args) {
        Thread t = new Thread(() -> {
            while (true) {
                try {
                    queue.take().run();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

            }
        });
        t.start();

        for (int i = 0; i < 10; i++) {
            queue.add(() -> {
                System.out.println("Hello");
            });
        }
    }

}