What is up-casting and down casting? with example
Answers were Sorted based on User's Feedback
When the level of hierarchies are considered, it is the super class at higher level & sub class at lower level. Hence the assignment of subclass to a superclass is up casting & super to a subclass is down casting.
Is This Answer Correct ? | 15 Yes | 1 No |
The assignment of a subclass instance to a reference
variable of the type "reference to super class" is
described as a narrowing cast, because you are switching
from a more detailed view to a one with less detail. It is
also called as up-casting.
Is This Answer Correct ? | 12 Yes | 4 No |
Answer / vamsi krishna srirangam
upcasting is used to acess the common methods of
subclass(which are redefined from super class) using super
class reference.
use:because of this only polymorphism is possible.
example:
lcl_truck,lcl_bus are subclasses to lcl_vehicle
vehicle_list type table of ref to lcl_vehicle.
lcl_vehicle = lcl_truck.
append lcl_vehicle to vehicle_list.
clear lcl_vehicle.
lcl_vehicle = lcl_bus.
append lcl_vehicle to vehicle_list.
clear lcl_vehicle.
now if you redefine the estimate_fuel method in each
subclass then that particular method only called because
fuel estimation is different for bus and truck.
Down-casting:
to take control back to the object that is called now.
to identify the triggered subclass object from the list of
available subclass objects.
?= means check whether the reference(path)
is same. if left hand path is equals to right hand path then
it copies the right hand path to left hand variable.
it is used to pick one from several
Is This Answer Correct ? | 4 Yes | 0 No |
What is the use of f4if_shlp_exit_example function module ? : sap abap data dictionary
How many types of tables exist and what are they in data dictionary?
Is it possible to pass data to and from include programs explicitly? : abap modularization
. How to transport scripts ?
what is difference between commit and rollback.?
Have you set up a back ground job? How to create a background job without a variant ? : abap bdc
What are the different types of view?
Example of table cluster and cluster tables.
What is asynchronous update?
What is a database view? : abap data dictionary
What is the advantage of structures? How do you use them in the ABAP programs?
What is performance tuning?