Difference between interface and abstract class? are they both same

Difference between interface and abstract class? are they both same

Hi,
An interface provides only the signatures of methods that any class implementing that interface will implement.
An abstract class provides implementation of the common functionalities present and declares methods specific to base classes as abstract.

Regards,
Sahil.



[SIZE=1]--Smile, it makes people wonder what you are thinking. :)[/SIZE]

[QUOTE=mahesh9920;18753]Difference between interface and abstract class? are they both same[/QUOTE]

An interface provides only the signatures of methods that any class implementing that interface will implement.
An abstract class provides signatures and also the functionality of the signature both are override it

[B]Interface :[/B]

1) Interface is pure contract. Any class implementing interface must override all methods provided by that interface.

2) There cant be function definition in interface.

3) We can not instantiate interface

[B]Abstract Class[/B]

1) Abstract class can contain function body.

2) Abstract class must contain at least one abstract method

INTERFACE:
- it contains only unimplemented methods
- may or may not be used.
- if you used interface all methods must be implemented.
- variable must be abstract and final
- methods take abstract as default.
- interface must be public.
- one class can implement number of interfaces.
- interfaces properties are included with [U]implements[/U] key word.
[B]ABSTRACT[/B]
- it contains both implented and unimplemented method.
- it allows both abstract and non abstract methods.
- it must be used if u declare it otherwise compiler gives an error.
- the abstract class must be contain at least one abstract method.
- it may be public or protected.
- only one class can extend abstract class.
- abstract properties are included with extends keyword.

hi
interface--It is set of abstract methods.It only has a definition of methods which include name of method,its signature.here none of the methods are implemented.
abstract class--A class is a abstract class when there is even one abstract method while other methods have body.

Abstract class cannot Instainted or Object cann't be created from Abstract class.
It contains both implemented and non Implemented Methods.


Interface contains abstract methods means non implemented method.

Abstract class and interfaces are completely different.

1) In an abstract class, you may also have some concrete methods( fully implemented. It can have all its methods as concrete, yet be declared as abstract) , but in an interface, all the methods ought to be abstract.

2)Abstarct class can never be instantiated, but you can indirectly instantiate an interface by instantiating the class which implements it and then use the its methods.

1)Abstract class is a collection of abstract methods and concrete methods or only abstract methods or only concrete methods
Interface is a collection of only abstract methods
2)the members of the abstract class are public(default),protected,static
the members of interface are implicitly public
3)A class can inherit one or more interfaces but a class can inherit only one abstarct class
4)abstract class can add more functiuonality without destroying the child classes
in an interface..creation of additional functions will have an effect on its child class due to necessary implementation of interface methods in child class

What is the difference between in-line and macro function in c, c++.

[QUOTE=mahesh9920;18753]Difference between interface and abstract class? are they both same[/QUOTE]

No
Abstract Class
1.Abastract class can have abstract and non abstract methods.
2. Abstract class is basically for inheritance purpose.
3. Abstract class can have method implementation also.
4. Variables can be declared in abstract class.

Interface
1. Interfaces have all methods abstract.
2. No access modifiers allowed in methods declared in interface.
3. No implementation of methods as all methods are abstract.
4. variables can not be declared in interfaces only methods and properties

Thanks to all, Very clearly every one tries to explain the difference between interface and abstract class.

no they aren't...
the reason is that
An abstract class may contain code in method bodies, which is not allowed in an interface. With abstract classes, you have to inherit your class from it and Java does not allow multiple inheritance. On the other hand, you can implement multiple interfaces in your class.

Hi,
Abstract class may declare concrete methods also. One class extends only one abstract class.
interface should declare only abstract methods. One class implement one or more interfaces. implementation of abstract methods in any class are declared as public implicitly.

FYI
SHASHI

1. Abstract classes can have concrete method while interfaces have no methods implemented.
2. Interface do not come in inheriting chain, while abstract class come in inheritance.
3. Abstract classes are faster than interfaces.
4. By default, all members in Interface is Public whereas members in Abstract class may have different.

[B]Re: Difference between interface and abstract class? are they both same [/B]
There are some diff b/w abstract and interface.
1>all the member in interface are abstract,without use a abstract keywoard.
2>in the abstract class use abstract and non abstract.if in the abstract class u use not abstract then u will declare method mody.

interface and abstract are both implemented internally inheritence concept

interface and abstract are both implemented internally inheritence concept.

in interface implement the inheritence between unrelated class and abstract implement inheritence between related classe.

one interface extends many interfaces at a time but an class extends one abstract class at time

Abstract Class vs. Interface

• An abstract class may contain complete or incomplete methods. Interfaces can contain only the signature of a method but no body. Thus an abstract class can implement methods but an interface can not implement methods.

• An abstract class can contain fields, constructors, or destructors and implement properties. An interface can not contain fields, constructors, or destructors and it has only the property's signature but no implementation.

• An abstract class cannot support multiple inheritances, but an interface can support multiple inheritance. Thus a class may inherit several interfaces but only one abstract class.

• A class implementing an interface has to implement all the methods of the interface, but the same is not required in the case of an abstract Class.

• Various access modifiers such as abstract, protected, internal, public, virtual, etc. are useful in abstract Classes but not in interfaces.

• Abstract classes are faster than interfaces.

what is the member hide?

Interface is the framework for methods . where only mehod signature and there is no implementation of a method.In Interface every method is abstract method.
In abstract class there abstract method signature is available and which class extend this super
class has to implement this abstract method.

1)Abstract class is a collection of abstract methods and concrete methods or only abstract methods or only concrete methods
Interface is a collection of only abstract methods
2)the members of the abstract class are public(default),protected,static
the members of interface are implicitly public
3)A class can inherit one or more interfaces but a class can inherit only one abstarct class
4)abstract class can add more functiuonality without destroying the child classes
in an interface..creation of additional functions will have an effect on its child class due to necessary implementation of interface methods in child class

I love Jave

abstract class is a signature of class, can't be instantiated .
it having some abstract members(both variables and methods) which are get implemented in to derived classes
Interface is heaving all its methods (no any veriables) without implemented and all its methods are defaultly public because they all get implemented in derived classes but in abstract class only some its members may public

1) abstract class may or maynot be contain abstract methods,but interfaces must contain abstract methods only
2)abstract class contains both abstract and concrete methods,concrete methods contain static,final and ordinary methods.
3)abstract class contains all concrete or all static methods or all final methods or all abstract methods or combination of all the above.
4)interface tells us what to do?,but not how to do
5)both abstract class and interface particpates in object creation through the concept of dynamic binding.

both are same but we can implements one or more at a time but we can extend one class at a time

Interface:

>It contains only abstract methods .
>it contains only constants but not instance variables.

abstract:

>it contains some abstract methods or concrete methods .
>it contains only instance variables.
:)

hi

Is java predefined or user-defined language ??
Can u please help me out. thanq

Hi,

An interface is called as a pure abstract class where non abstract member functions are not allowed but in case of abstract classes we can have both abstract and non abstract member functions based on the requirement...

a) All the methods declared inside an interface are abstract whereas abstract class must have at least one abstract method and others may be concrete or abstract.

b) In abstract class, key word abstract must be used for the methodsWhereas interface we need not use that keyword for the methods.

c)Abstract class must have subclasses whereas interface can’t have subclasses.

well,an abstract class can be thought of as consisting pure virtual methods:methods with zero body i.e just a signature of a method but moreover it may contain a definition of the method prototype too. abstract classes don't inhibit users to give method body in abstract class only but contrary to that interface does not allow a user to give method definition along with method prototype in an interface rather we need to create a class that will b implementing the method prototypes using overridden methods philosophy of OOP.