READING
CHAPTER 10
SECTION 2

- arrays can also store objects
- declare an array of objects
  - use the name of the class

    <class name>[] <identifier> = new <class name>[<size];
    
    - individual elements of an array of objects are intialized to null
- each individual element must also be created

  <identifier>[<index>] = new <class name>();

- after an element is added, that array index points to an object
- accessing members and methods of an object in an array
  
  <identifier>[<index>].<method/member>;

  - use indexed expression to refer to an object instead of a variable
- remove an object from an array
  - set that element to null
  - pack the array so that real elements occur at the beginning and null elements occur at the end
    - move each subsequent element over one: better if objects are ordered
    - move the last real element into the hole: better if objects are not ordered
  - if allow null references, search routine must account for this
    - either skip null references
    - or stop when hit first one
  - assigning the array element to null does not actually erase the object
    - automatically deallocated during garbage collection when no more references point to it

Quick Check:
1. a and d are invalid
2. for (int i = 0; i < 100; i++) {
       if (friend[i].getAge() > 20) {
           System.out.println(friend[i].getName());
       }
   }