When a collection is ordered, it means you can iterate through the collection in a non-random order.
A sorted collection means that the order in the collection is determined according to some rule or rules.
ArrayList is a growable array.
Vector methods are synchronized for thread safety.
A LinkedList is ordered by index position, like ArrayList, except that the elements are doubly-linked to one another.
A Set doesn't allow duplicates.
A HashSet is an unsorted, unordered Set.
A LinkedHashSet is an ordered version of HashSet that maintains a doubly-linked List across all elements.
The TreeSet is one of two sorted collections (the other being TreeMap).
A Map cares about unique identifiers.
The HashMap gives you an unsorted, unordered Map.
Hashtable key methods are synchronized.
HashMap lets you have null values as well as one null key
A Hashtable doesn't let you have anything that's null.
LinkedHashMap collection maintains insertion order.
A TreeMap is a sorted Map.
PriorityQueue create a "priority-in, priority out" queue as opposed to a typical FIFO queue.
AbstractCollection implements all of the methods of the Collection interface except iterator and size.
It is extended by AbstractList and AbstractSet.
AbstractList extends AbstractCollection and implements the List interface.
AbstractSet extends AbstractCollection and implements the Set interface.
AbstractMap implements the Map interface.
AbstractSequentialList extends the AbstractList class, and provides the basis for the LinkedList class.
Maps Sets Lists Queues Utilities
HashMap HashSet ArrayList PriorityQueue Collections
Hashtable LinkedHashSet Vector Arrays
TreeMap TreeSet LinkedList
LinkedHashMap
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