extends class and implements interface in java
61 extends should go before implements:
oop
What are metaclasses in Python?
A metaclass is the class of a class. A class defines how an instance of the class (i.e. an object) behaves while a metaclass defines how a class behaves. A class is an instance of a metaclass. While in Python you can use arbitrary callables for metaclasses (like Jerub shows), the better approach is to make it … Read more
Difference between abstraction and encapsulation?
What is the precise difference between encapsulation and abstraction?
Difference between virtual and abstract methods
Virtual methods have an implementation and provide the derived classes with the option of overriding it. Abstract methods do not provide an implementation and force the derived classes to override the method. So, abstract methods have no actual code in them, and subclasses HAVE TO override the method. Virtual methods can have code, which is … Read more
Is C++ an Object Oriented language?
C++ is usually considered a “multi-paradigm” language. That is, you can use it for object-oriented, procedural, and even functional programming. Those who would deny that C++ is OO generally have beef with the fact that the primitive types are not objects themselves. By this standard, Java would also not be considered OO. It is certainly … Read more
java – invalid method declaration; return type required
In your method setDetails you haven’t specified anything for the return type, if it is not returning anything then specify void For Voter class for Candidates class One other thing, (Thanks to Frank Pavageau) your class name is Candidates and you have defined the constructor with Candidate without s, that is why it is being considered as a normal method, and thus should have a return type. You your rename … Read more
java – invalid method declaration; return type required [duplicate]
On a Java OOP project I got three errors on my constructor: .\Voter.java:14: error: invalid method declaration; return type required .\Candidates.java:7: error: invalid method declaration; return type required .\Candidates.java:14: error: invalid method declaration; return type required codes for constructor: i declared my constructors like this: Anything I missed?
What is polymorphism, what is it for, and how is it used?
If you think about the Greek roots of the term, it should become obvious. Poly = many: polygon = many-sided, polystyrene = many styrenes (a), polyglot = many languages, and so on. Morph = change or form: morphology = study of biological form, Morpheus = the Greek god of dreams able to take any form. So … Read more
Are static class variables possible in Python?
Variables declared inside the class definition, but not inside a method are class or static variables: As @millerdev points out, this creates a class-level i variable, but this is distinct from any instance-level i variable, so you could have This is different from C++ and Java, but not so different from C#, where a static member can’t be accessed using … Read more
Reading from file in c++ ifstream
What the inFile >> S does is take in the file stream, which is the data in you file, and uses a space delimiter (breaks it up by whitespace) and puts the contents in the variable S. For example: If we had a file that had the follow contents and we used inFile >> S with our file: we … Read more