The java collection framework consists of three main parts as shown in following image.
Core Collection Interfaces
|Collection||A basic interface that defines the normal operations that allow a collection of objects to be maintained or handled as a single unit.|
|Set||The Set interface extends the Collection
interface to represent its mathematical
namesake: a set of unique elements.
|SortedSet||The SortedSet interface extends the Set
interface to provide the required functionality
for maintaining a set in which the elements
are stored in some sorted order.
|NavigableSet||The NavigableSet interface extends and
replaces the SortedSet interface to maintain a
sorted set, and should be the preferred choice
in new code.
|List||The List interface extends the Collection
interface to maintain a sequence of elements
that can contain duplicates.
|Queue||The Queue interface extends the Collection
interface to maintain a collection whose
elements need to be processed in some way,
i.e., insertion at one end and removal at the
other, usually as FIFO (First-In, First-Out).
|Deque||The Deque interface extends the Queue interface
to maintain a queue whose elements can be
processed at both ends.
|Map||A basic interface that defines operations for
maintaining mappings of keys to values.
|SortedMap||The SortedMap interface extends the Map
interface for maps that maintain their
mappings sorted in key order.
|NavigableMap||The NavigableMap interface extends and
replaces the SortedMap interface for sorted
Note- Map interface does not extend Collection interface because conceptually , a map is not a collection.Map does not contain elements, it contains mappings from a set of key(objects) to a set of value objects.