java - When we use Referrence type and Object Type -

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i having doubt regarding arraylist , list. in case should use arrarylist like:

arraylist obj = new arraylist();

and in case should use list interface.

list obj =  new arraylist();

after googling , study found nothing... please let me know difference between them.

thanks in advance :-)

if need call method specific implementation, use implementation.

when write :

list obj =  new ... //arraylist() or linkedlist()

the compiler knows obj list. hence, cannot use methods specific 1 implementation.

for example, if need access last element of linkedlist, need declare :

linkedlist = obj = new linkedlist();

now, obj linkedlist. hence, can use obj.last().

GHI