Copying List Type to an Abstract List

Question

I have two classes that inherit from a single abstract class. The two classes dictate which type of AbstractList to use, either and ArrayList or LinkedList.

public class ArrayListMergeSort extends MergeSortData
{
public ArrayListMergeSort()
   {
    super();
    data= new ArrayList<String>();
   }
}

I was wondering how I would be able to make a new temporary AbstractList in the abstract class based on which type of list data is?

Answer 1

You could have an abstract method returning a List in the abstract class MergeSortData :

public abstract List<String> getNewList();

Then, you implement this method in each sub-class.

For example, in ArrayListMergeSort :

public List<String> getNewList() {
    return new ArrayList<String>();
}

Any method of the abstract class MergeSortData can then call getNewList() to obtain a new List of the correct implementation.