string is immutable - it stores contants
stringbuffer is mutable - you manipulate string add, delete, insert
Type: Posts; User: Akilan Paul; Keyword(s):
string is immutable - it stores contants
stringbuffer is mutable - you manipulate string add, delete, insert
what is the rules for primary key?
it wont accept null and duplication
isn't
then how we can store NULL in primary key field
interface is useful