how to return numbers by column from objects that have array list attribute

Question

I have a class where I am creating different "Processes", an attribute of this class is an linked list of Integers. I have created different class objects and to make it easy to loop through all of the process objects I have created, I am storing these objects in an arraylist in my main class - i understand how to individually access each linked list. What I am doing now is looping through my arraylist to access each objects linked list and adding these numbers into a queue called processQueue in my main class. so currently I have something like

ArrayList<MyClassName> processObjects = new ArrayList<MyClassName>();

for(int i = 0; i < processObjects.size(); i++){
    for(int j = 0; j < processObjects.get(i).getQueue().size(); j++){
        processQueue.add(processObjects.get(i).getQueue().get(j));
    }
}

(this would be process object 1 linked list) = {2,1,5,4} (this would be process object 2 linked list) = {3,2,6,1}

so in the case that these two linkedlists are proviced, I would want processQueue to look like {2,3,1,2,5,6,4,1} - but instead right now im returning {2,1,5,4,3,2,6,1}

Any help for me understanding conceptually how to accomplish my goal of adding to the queue by column would be much appriciated!

Initially, I tried to do this the way i would with a 2D array like this for example

int[][] bruh = new int[3][3];
Test test = new Test();

int i = 0;
for(int row = 0; row < bruh.length;row++){
    for(int col = 0; col < bruh.length; col++){
        bruh[col][row] = i;
        test.bruh.add(i);
    }
    i++;
}

But because i will not know the size of the linkedLists, this approach causes size errors

Answer 1

One way to do it would be to create an array of queue objects and then loop through that array to create your new ArrayList.

To deal with the difference in size - you can use conditionals to check whether a queue has a value at a particular index. This can be done by comparing the current index to the size of a particular queue.