The java.util Package - The Collections Framework

• a collection is a container or object that groups multiple objects into a single unit
  
  
• a Collections Framework provides a unified system for organizing and handling collections and is based on four elements:
  1. Interfaces that characterize common collection types
  2. Abstract Classes which can be used as a starting point for custom collections and which are extended by the JDK implementation classes
  3. Classes which provide implementations of the Interfaces
  4. Algorithms that provide behaviours commonly required when using collections ie search, sort, iterate, etc.
  
  
  
• the Collection Framework in Java has six core collection Interfaces:

• the Collection Framework also provides an interface for traversing collections: Interator and it's subinterface ListIterator
  
  
• the Iterator interface should be used in preference to the earlier Enumeration interface