[polymorphism] Forum Topics

Hi I'm creating a code for my class and what I'm trying to do is to create a triangle class that is derived from abstract class TwoDimShape. However; when I create the triangle class and use base as a variable I get an error. My teacher wants us to use …

i can understand it when we want to implement polymorphism in c++ we use virtual functions and function overriding but when we want to implement polymorphism in java then we do not use virtual methods why. in java we use simply reference object that can store the address and use …

I'm trying to create a program that passes arguments of size of three shapes, a circle, a triangle, and a rectangle. I got those but everytime I run the code it displays the arguments as 0 instead of giving me the shape dimension. Here is the code. using System; class …

Hello I am trying to create a class that called Lootable and create subclasses such as trunk, locker, etc. that will contain items that can be looted, they will inherit their lootability from the Lootable class. I am thinking of using the ArrayList for this. I have thought of different …

I have an abstract class CArticle and two derived classes CBook and CMagazine. I also have a class CLibrary where i want to add articles. Its members are an int variable to count the articles and a double pointer of CArticle. I have the following main function: int main() { …

<? super Animal> means animal or it's superclass only. Then why inside the method it's allowing to add Dog object even though it's a subclass of Animal? This program compiles and runs! import java.util.*; class Cat {} class Animal{Animal() {System.out.println("Animal constructor");}} class Dog extends Animal{Dog() {System.out.println("Dog constructor");}} public class GenericDemo5 …

Compiles fine. But at runtime it gives ClassCastException. My doubt is that why is it so even though st which is of type Sample1 gets casted to Sample2 and generates exception even though Sample2 IS-A Sample1.

class Mixer { Mixer() {} Mixer(Mixer m) { m1 = m; } Mixer m1; public static void main(String args[]) { Mixer m2 = new Mixer(); Mixer m3 = new Mixer(m2); m3.go(); Mixer m4 = m3.m1; m4.go(); Mixer m5 = m2.m1; m5.go(); } void go() { System.out.println("hi"); } } The answer …

So this is mainly a Design/Clean Coding sort of question, I know I've read something about this previously but I can't find it, I believe it's in one of my reference books on C/C++ so it wouldn't likely be useful to my predicament. This question includes a lot of Java …

I'm working on a program that demonstrates polymorphism. It asks the user to create an elementary, high school, or college student. Once a student is created, it is stored in an array list. When prompted, the program is suppose to print out each of the student's information. How do I …

Hi all, I have started finding lots of uses for abstract classes to define interfaces for common functionality using polymorphism and i know that using polymorphism and virtual functions incurrs some additional call cost of functions. So what im wondering is can i get the best of both worlds? consider …

HELP ME PLEASE. I AM A 1ST YR COLLEGE STUDENT :/ Define an interface Filter as follows: public interface Filter { boolean accept(Object x); } Modify the implementation of the DataSet class to use both a Measurer and a Filter object. Only objects that the filter accepts should be processed. …

Ok I am a programming student and need help with a problem, I already have most of it (so I don't need you guys to do my hw :P) but I am having problems with am, and I am not even sure if I am doing it right. [B]Problem:[/B] (The …

Hey all:) I'm learning Java and I'm having a little trouble on a polymorphic write-to-file function. Let me quickly explain my project: I have an abstract class Mammal, with non-abstract children Horse, Cow etc. I have a Main program that creates a couple Horses and Cows, and store these in …

Hello all I have a query,may be silly but i have to clear it.IT IS REGARDING THE UPCASTING.I want to "when we can invoke the methods of base class using the object of derived class.then what is the need of assigning the subclass object to base class reference." I mean …

I have a design question which I have not been able to find a satisfactory answer for by searching. Essentially, I have a class - Base - that contains a vector of pointers to another class - Node. However, I would like to be able extend both the Base and …

Hi, just a quick question (i hope!!), i'm working on an assignment where i need to build a user-defined library of shapes. The class structure is to have "shape" as a base-class with both 2d and 3d shapes as derived classes. I've handled this by storing them in a vector …

Hello Everyone, I'm trying to implement a Polymorphic Queue. Here is my trial: [CODE]QQueue <Request *> requests; while(...) { QString line = QString::fromUtf8(client->readLine()).trimmed(); if(...)){ Request *request=new Request(); request->tcpMessage=line.toUtf8(); request->decodeFromTcpMessage(); //this initialize variables in request using tcpMessage if(request->requestType==REQUEST_LOGIN){ LoginRequest loginRequest; request=&loginRequest; request->tcpMessage=line.toUtf8(); request->decodeFromTcpMessage(); requests.enqueue(request); } //Here pointers in "requests" do not …

[B]This has been solved! Look at the end of this post.[/B] Hello! I'm having some trouble here with polymorphism, as I need to access methods in a subclass from an array of superclass objects. This method is called parseCommand(Command c); The method exists in the superclass and is overridden in …