Constructors for ArrayList Objects

To declare a reference variable for an ArrayList do this:

ArrayList<E> myArray;  

Replace E with the class you want. For example, to construct an ArrayList of references to String, do this:

ArrayList<String> stringArray;  

myArray is a reference to a future ArrayList object. The future ArrayList object will contain an array of references to objects of type E or to a descendant class of E.

An ArrayList object is constructed by:

myArray = new ArrayList<E>();  

The initial capacity is 10 cells, although this increases as needed as references are added to the list. Cells will contain references to objects of type E (or a descendant class).

To both declare a reference variable and construct an ArrayList, do this:

ArrayList<E> myArray = new ArrayList<E>();  

To declare a variable and to construct a ArrayList with a specific initial capacity do this:

ArrayList<E> myArray = new ArrayList<E>( int initialCapacity );  

The initial capacity is the number of cells that the ArrayList starts with. It expands beyond this capacity if needed. Expanding the capacity of an ArrayList is slow. To avoid this, estimate how many elements are needed and construct an ArrayList of that many plus some extra.