Collection

http://en.wikibooks.org/wiki/Java_Programming/Collection_Classes

the UML diagram are very clear on this page.

The Java JDK contains two high level Interfaces:

• java.util.Collection
• java.util.Map

here is no direct implementation for the java.util.Collection interface. The Collection interface has three sub interfaces.

java.util.Set (implementation are TreeSet,HashSet ...)

Set cannot have duplicates in it.

java.util.List

( implementation are Vector,Stack,ArrayList,LinkedList,AttributeList,RoleList...)

interfaces SortedSet

java.util.Queue ( implementation are: PriorityQueue, ArrayBlockingQueue ..)

interface: BlockingQueque

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java.util.Map implementations are:
TreeMap,HashMap, HashTable,LinkedHashMap,IdentityHashMap ..

Before selecting a particular collection implementation, ask the following question:

• Can my collection contain the same elements, i.e. are duplicates allowed?
• Can my collection contain the null element?
• Should the collection maintain the order of the elements? Is the order important in any way?
• How do you want to access an element? By index, key or just with an iterator?
• Does the collection need to be synchronized?
• From a performance perspective, which one needs to be faster, updates or reads?
• From a usage perspective, which operation will be more frequent, updates or reads?