In general programming terms, a concrete class is one which can be instantiated, while an abstract class can only be instantiated via a fully implemented subclass.
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.
Some difference between an interface and an abstract class are: a. All variables in an interface are public, static and final but that is not the case in abstract classes b. An abstract class can have both abstract and concrete methods but an interface cannot have concrete methods c. An abstract class can extend other classes and implement interfaces, while an interface can only extend other interfaces.
Below is the main difference between the 3 components:Concrete class - Provides implementation for all its methods & also for methods from extended abstract classes or implemented interfacesAbstract class - Does not provide implementation for one or more of its methodsInterface - Does not provide implementation for any of its methods
A more prcise description of difference is as follows.... an interface is a specification of a set of methods that the implementation class must adhere to, while an abstract class is indeed an implementation class albeit a class that is not concrete, i.e., one cannot directly instantiate an abstract class.
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.
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.
The same way you create a concrete method in a concrete class. When a class is abstract, it can contain abstract methods. That doesn't mean that all methods must be abstract. Hope this helps.
A constructor of a class in invoked when a object of that class is created. As an abstract class can't have an object, so we can't create a constructor of the abstract class. But we can create a constructor of a concrete subclass of that abstract class and we have to pass the object of that concrete subclass to the abstract 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.
A Concrete class
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.
A final class cannot have any subclasses. An abstract class cannot be instantiated unless it is extended by a subclass.
Yes. But cannot extend both of them at the same time. Meaning you can extend only one class at a time and that class can be abstract class or concrete 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
Assume a "simple" class be a class without the keyword "abstract".You cannot create an instance of an abstract class. An abstract class is intended to be inherited from (to be extended or derived from).A "simple" class is a class that an instance can be created from (via new operator)
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.
Yes. Abstract class can have constructor which is called when an instance is created for it's concrete class.... satish koleti
abstract class no defination used by derieved class where virtual base class is defination that can be overriden later on
Abstract classes are to be extended until to a concrete class.Can have both abstract & non abstract methods.An Abstract class can not be instantiated.A non abstract class can be extended to an abstract class.If At least one abstract method present in a class then that class must be abstract.abstract & final modifiers can never be together.abstract classes can have both abstract methods & non abstract methods.
Abstract classes are classes that can't be instantiated directly. In other words, you are meant to create subclasses, which you instantiate.
The main advantage of an abstract class it the fact that, you can actually write methods that are not abstract. i.e., you can write methods with concrete code inside them. So when an abstract class is extended, all the abstract methods will be implemented by the child class but the child class will also inherit the code of this concrete method you wrote in the abstract class. This is the only thing an interface cannot do and is the advantage of an abstract class over an interface.
an abstract class is nothing but class which contains both abstract and concrete methods for abstract class we r nt create object Syntax for pure abstract class is abstract class x { public void abstract y(); public void abstract z(); public void abc() { }
The difference are:An abstract class can have methods that actually have code inside them whereas an Interface cannot (An Interface can be thought of as a 100% pure abstract class)All variables in an Interface are public, static, final whereas that is not the case in Abstract classes
An abstract class can have a combination of abstract methods and normal methods. Interfaces cannot implement any methods themselves, all have to be abstract. Other classes can extend only one class (abstract or not), but can implement as many interfaces as they want.