Java – run runnable multiple times in completable future

I want to execute multiple threads, which will try to add to my custom list mylist at the same time, but I can't see any output when I try to count

public static void main(String[] args) {

        MyList<String> list = new list<String>();

        MyRunner<String> myRunner = new MyRunner<String>(list);

        ExecutorService threadPool = Executors.newFixedThreadPool(4);

        for(int i = 0; i < 20; i++) {
            CompletableFuture.runAsync(new MyRunner<String>(list));
        }

        try {
            threadPool.awaitTermination(100l,TimeUnit.SECONDS);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println(list.getCount());
}

Runner class:

class MyRunner<String> implements Runnable {

    MyList<String> list;

    public MyRunner(MyList <String> t) {
        this.list = t;
    }

    @Override
    public void run() {
        for(int i = 0; i < 200; i++) {
            list((String) (i + Thread.currentThread().getName()));
        }

    }
}

class MyList：

public class MyList<T> {

    Queue<T> blockingQueue;
    Lock lock;

    long count;

    public MyList() {
        blockingQueue = new LinkedList<>();
        count = 0;
        lock = new reentrantlock();
    }

    public void add(T singleTon) {
        lock.lock();
        blockingQueue.offer(singleTon);
        count +=1;
        lock.unlock();
    }

    public long getCount() {
        return count;
    }


}

Follow up questions:

The countdownlatch program does not end The number of sysouts is 10001, and the last output is in runnable: 9: pool-1-thread-1

Countdownlatch implementation:

public static void main(String[] args) throws InterruptedException {

        MyList<String> mylist = new MyList<>();

        CountDownLatch latch = new CountDownLatch(10);

        ExecutorService executorService = Executors.newFixedThreadPool(4);


        for(int i = 0; i < 1000; i++) {
            CompletableFuture.runAsync(new MyRunner<String>(mylist,latch),executorService);
        }

        latch.await();

        System.out.println(mylist.count);
    }


class MyRunner<String> implements Runnable {

    MyList<String> mylist;
    CountDownLatch latch;

    public MyRunner(MyList<String> mylist,CountDownLatch latch) {
       this.latch = latch;
       this.mylist = mylist;
    }

    @Override
    public void run() {
        for(int i = 0; i < 10; i++) {
            System.out.println("In runnable: "+ i + " : "+ Thread.currentThread().getName());
            mylist.add((String)("" + i));
        }

        latch.countDown();
    }
}

Solution

You call completabilefuture. You do not use the executor you created runAsync(Runnable runnable).

CompletableFuture.runAsync(new MyRunner<String>(list),threadPool);