Any class which has one or more abstract methods is called an abstract class. But in the normal class we can't have any abstract methods.
We cannot create an object for the abstract classes.
When we inherit the abstract class we should implement the abstract method which we inherit.
Association class is describing the relationship between classes. An abstract class is just 1 class, provides some abstraction behaviors that may be (but do not have to) derived, overridden from.
Abstract class is built to promote inheritance whereas a final class is built to avoid inheritanceAn Abstract class can be extended by another class whereas a final class cannot be extended
In general, the differences are that interface has(1) no fields and(2) no implementation of methodsbut in UML interface may have features (fields), so the difference left is that interface in UML has no implemented methods while abstract class by definition is partially implemented class.
If a class has one abstract method ,the class has to be an abstract class.Methods can be implemented in abstract class.Whereas a interface is like a abstract class...the only difference being that the methods are never implemented in Interface.
We can't instantiate both interfaces and abstract classes.The only one difference between them is that an interface can't contain concrete(fully defined) methods where as an abstract class may contain them.An abstract class not necessarily contain abstract methods. we can make a class as abstract class even it does not has any abstract methods.When there is a need to write both abstract and concrete methods in a single unit we have to use an abstract class instead of an interface since an interface cant contain concrete methods.All the fields(or properties) of an interface are by default 'static final' even when you don't mention explicitly. And all methods are 'public abstract'.But in an abstract class we can have any type of fields and methods.
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Association class is describing the relationship between classes. An abstract class is just 1 class, provides some abstraction behaviors that may be (but do not have to) derived, overridden from.
There is no difference with method declaration and implementation between abstract and non-abstract classes. You do the exact same thing when writing a concrete method in either an abstract or non-abstract class.
Abstract class is built to promote inheritance whereas a final class is built to avoid inheritanceAn Abstract class can be extended by another class whereas a final class cannot be extended
An interface can only have abstract methods or constants in it. A class can have both that and everything else in Java.
You can't put an abstract method (pure-virtual method) in a normal class because the normal class would become abstract itself. Only non-abstract classes can be physically instantiated as objects, and only if they fully implement all the abstract methods inherited from their base classes.
In general, the differences are that interface has(1) no fields and(2) no implementation of methodsbut in UML interface may have features (fields), so the difference left is that interface in UML has no implemented methods while abstract class by definition is partially implemented class.
If a class has one abstract method ,the class has to be an abstract class.Methods can be implemented in abstract class.Whereas a interface is like a abstract class...the only difference being that the methods are never implemented in Interface.
We can't instantiate both interfaces and abstract classes.The only one difference between them is that an interface can't contain concrete(fully defined) methods where as an abstract class may contain them.An abstract class not necessarily contain abstract methods. we can make a class as abstract class even it does not has any abstract methods.When there is a need to write both abstract and concrete methods in a single unit we have to use an abstract class instead of an interface since an interface cant contain concrete methods.All the fields(or properties) of an interface are by default 'static final' even when you don't mention explicitly. And all methods are 'public abstract'.But in an abstract class we can have any type of fields and methods.
We can access a Friend function from any other class in which friend function is introduced or declared even if the other class is not a member of first class. But when we use normal member function, we can have its access only in the derived classes of the first class. This is the basic difference between a friend function and a normal member function.
The term interface class does not exist in C#. If this is a term describing a class being an interface to other component (human, subsystems, etc), it is very application specific. The designer of that application should know the abstraction.However, C# does have another type called interface. An interface is NOT a class. An interface defines the intention of some behaviors that classes may be extended it and provides the implementation. The intention, is nothing but method signatures, which defines the return data type, the method name, and any method arguments and associated data type. The implementation is the code of the method. Interface is used for separating the concern of design and implementation.Abstract class is a class with abstract keyword. It can be just like a class without that keyword (then, why it is an abstract class?). But it may have some methods or properties defined as abstract. These abstract methods, like the method signatures of an interface, defines the intention.The subclasses of such an abstract class would need to implement those abstract methods (providing the code).There are more common, differences between interfaces and abstract classes, please see answer(s) of those related questions in C# category.
All the methods declared inside an Interface are abstract. Where as abstract class must have at least one abstract method and others may be concrete or abstract. In Interface we need not use the keyword abstract for the methods.