Thread unsafe method getNext()

import net.jcip.annotations.NotThreadSafe;

@NotThreadSafe
public class UnSafeSequence 
{
    
    private int value;
    
    public int getNext()
    {
        return value++;
    }
}

1. The initial purpose is to test the return value of the getNext() method executed by the thread pool

The main function is as follows:

public class UnSafeQequenceTest
{

    /**
     * @throws ExecutionException
     * @throws InterruptedException
     */

    public static void main(String[] args)
    {
        UnSafeSequence unSafeSequence = new UnSafeSequence();

        ExecutorService executors = Executors.newCachedThreadPool();
        for (int i = 0; i < 100; i++ )
        {
            executors.submit(() -> System.out.println(unSafeSequence.getNext()));
        }
        executors.shutdown();
    }

}

The results were as disorganized as expected:

2. By the way, use Future to receive the results of thread execution

The main method is modified as follows:

public class UnSafeQequenceTest
{

    /**
     * @throws ExecutionException
     * @throws InterruptedException
     */

    public static void main(String[] args)
        throws InterruptedException, ExecutionException
    {
        UnSafeSequence unSafeSequence = new UnSafeSequence();
        List<Integer> lstNumber = new ArrayList<Integer>();

        ExecutorService executors = Executors.newCachedThreadPool();
        for (int i = 0; i < 100; i++ )
        {
            Future<Integer> future = executors.submit(() -> unSafeSequence.getNext());
            Integer temp = future.get();
            System.out.println(temp);
            lstNumber.add(temp);
        }
        Integer max = 0;
        for (Integer e : lstNumber)
        {
            if (e >= max)
            {
                max = e;
            }
            else
            {
                System.out.println(e);
                System.out.println(lstNumber);
            }
        }
        executors.shutdown();
    }

}

The result of the execution is:

There's no problem with the order of the output, WTF? It's not normal

Is it caused by the main thread blocking when the Future object gets the thread return result?