collections mainly used to store different types of objects as a single entity.
Coolection is a interface.list and set interfaces extends colletion interface.collection is a base interface for all collection classsesand interfaces.In this we have
1)arraylist class.2)linked list
3) vector class.4)stack. these clsses implements list interface.
Set implemented classess are1)hashset2)linkedhashset
Sorted set implemented classses are1)Tree Set.
Another on emap inter faceimplemented classes are 1)hashmap2)linked hashmap3)hashtable.
there are slight differnces are there. if you go through a book khalid moghul you will get neat expla nation.