Array - ArrayList / Array List - Linked List

Array and Array Lists

Arrays

• Fixed length
• Anything => Primitives (integer, long, boolean) and also Objects (string, Dog, etc)

ArrayList

• Dynamic length

• Only hold objects. ArrayList => Error! but can you can use its class wrapper, e.g.: Integer for int.

• Access elements
  array[1];
arrayList.get(1);

• Get length
  array.length;
arrayList.size();

• Add elements
  Cannot do it with Arrays
arrayList.add("New element"));

• Set an element
  array[0] = "New element";
arrayList.set(0, "New element");

• Remove elements
  Cannot be done it in arrays
arrayList.remove(1)
  or
  arrayList.remove("Name of element to be removed")

Array Lists and Linked Lists

• They are both part of the Collection framework and they implement the List interface.

LinkedList

• Each element is called a node and it has a reference / pointer to the next and the previous node.
• The linked list start with a pointer to the first element (HEAD).
• They are not in contiguous memory spots.

ArrayList

• Good performance for random access.
• Not so good when adding or removing new elements, because it needs to run over all the array for changing only one element.