collections i code example
Example: collections
LIST: Can store duplicate values,Keeps the insertion order.
- ArrayList not syncronized, array based class
- LinkedList not synchronized, doubly linked
- Vector is synchronized, thread safe
SET: Can only store unique values,And does not maintain order
- HashSet can have null, order is not guaranteed
- LinkedHashSet can have null and keeps the order
- TreeSet sorts the order and don't accept null
QUQUE :Accepts duplicates, Doesn't have index num,
First in first our order.
MAP:is a (key-value format)
and keys are always unique,
and value can be duplicated.
- HashTable don't have null key, sychronized(thread-safe)
- LinkedHashMap can have null key, keeps order
- HasHMap can have null key, order is not guaranteed
- TreeMap doesn't have null key and keys are sorted
Examples
■ I have used TreeSet to print dropdown list in for
non duplicate values and ascending order
■ I have used HashMaps to compare values from
a database with expected values