polymorphic Arrays.

Question

i was practicing polymorphism by making a super class and subclasses. I made a superclass Animals and the subclases, dog,lion and cat. I connected them to the super class through inheritance. Then i made a method in the superclass and then i overrode them in each subclass except for the dog subclass. Then i made use of polymorphism in my main class when establishing the object to call each method , all the methods ran perfect for each class except the dog class. I then overrode the method in the dog class and it worked fine. Why is this so?

Answer 1

I fixed your code to run, now it seems fine. Try it and tell me what is the problem with it, what do you expect?
https://code.sololearn.com/c92UMYVkHc5Y/?ref=app

Answer 2

Link here you example.

Answer 3

your fixed does exactely what I expected. the dog uses animals method, the other two their own implementation.

Answer 4

Did you see my fixed code? Your expectations were good. You needn't override that method in Dog and it works.

Answer 5

And @Override annotation should be used to avoid typo problems.

Answer 6

https://code.sololearn.com/cKbNOkDyT6zo/#java
i just made this so ignore all the errors but this will allow you to understand what i said.

Answer 7

please fix the example code so that it will compile.
- public and class in lowercase
- Animal without () braces
- there is an unmatched } in your main method
- assiggnments need to goto the array Ani, not the class Animal

Answer 8

@Volker Thank you for the help @ Tamas Thank you for fixing my code. My initial idea was that i wanted to override all the subclass methods to the sound each animal made but since i already made the method in the super class Animal which outputs "woof-woof"- which is the sound made by a dog, i thought it would be unnecessary to to override the method in the dog subclass since it already inherited the correct method.from the super class.
The problem- when i did not override the dog class method, it gave me a fault when i made the object and tried calling the method with the correct syntax.

Answer 9

as it is not necessary to make all classes static, I also fixed the code. please observe that usually you should
- declare a package for your code (not working in the playground)
- you should split your classes in several files.
rule of thumb: each class in it's own file (except for inner and anonymous classes). As far as I know this is also not possible in the playground.
additionally I put a second output loop in the main using foreach to iterate on the animals.
https://code.sololearn.com/cE234wsv26N1/?ref=app

Answer 10

@Override is nice, but at least for implementing an interface IT's misleading IMHO.
similar like repeating virtual each time in C++ derived classes, you will find here discussions if and when to do.
I added the annotation to my code :)

Answer 11

@Tamas, yes i did and understand what the problem was ,Thank you!