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Interface vs Abstract Class (general OO)
When to use abstract class or interface?
Can you provided implementations on a abstract class?
what's the difference between these two?
and when will I know when will I know to use them?
This pages gives a good comparison: http://download.oracle.com/javase/tutorial/java/IandI/abstract.html . You could have found it with a very quick google search.
Interface is used for defining a contract. Abstract classes are used for defining some methods which are common to all descendants and possibly some methods which will differ(they will be abstract). With interfaces or abstract classes polymorphism is reached.
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This question already has answers here:
Interface vs Abstract Class (general OO)
(36 answers)
Closed 5 years ago.
If we can have 100% abstract class with all abstract methods that will work equivalent to Interface.Why we have interface and how it is better than 100% abstract class???
A class can only inherit from one abstract class, but it can implement as many interfaces as its developer wants to. That's why you should prefer interfaces over abstract classes, unless you have to provide an implementation of a method.
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Do/can abstract classes replace interfaces? [duplicate]
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what is the actual use of interface in java? [duplicate]
(6 answers)
Closed 7 years ago.
In java there is interface which having only abstract method means method declration only and those methods are implement in class that implement interface so why to use interface which has only declaration .This question is asked in interview.
Interfaces are used for only declaration of methods because it can achieve multiple behavior. It is the class's responsibility to implement the interfaces and define their methods as they desire.
Interfaces allow same methods to be implemented in different manner by implementing classes, which allows you to achieve behavioral facility.
For understanding sake, you can consider interfaces exist so you can achieve behavioral approach for your application, and class exist to achieve characteristic approach.
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Java abstract interface
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Closed 9 years ago.
As we know, interface is to define some method, but some interface defined as a abstract interface, but why ?
for example:
public abstract interface Test{
}
what is the advantage for using abstract to define a interface?
There is no need to add that abstract key word. It's redundant there.
Interfaces are implicitly abstract.
Language Spec JLS# 9.1.1.1 abstract Interfaces
Every interface is implicitly abstract.
This modifier is obsolete and should not be used in new programs.
refer to http://docs.oracle.com/javase/tutorial/java/IandI/createinterface.html for the same.
Also see https://stackoverflow.com/a/18778307/805378 to get the difference between abstract and interface.
to make a class 100% abstract without using 'abstract'.
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When shall we go for interface or abstract class in Java?
I have a doubt in java.I know about the interfaces and abstract classes.But I want to know specifically when to use interface and when to use abstract classes in java and android.I want a practical explanation with real world example not a theoretical or documented one.
Thanks.
The key difference is that you can implement multiple interfaces in a
class, but only extend a single abstract class.
Interface is used when you only want to declare which methods and members a class MUST have. Anyone implementing the interface will have to declare and implement the methods listed by the interface.
If you also want to have a default implementation, use abstract class. Any class extending the abstract class will have to implement only its abstract methods and members, and will have some default implementation of the other methods of the abstract class, which you may override or not.
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Possible Duplicate:
Interface vs Abstract Class (general OO)
I am little bit familiar with the terms Abstract class and the interface.
But i want to know in which situation i have to use the interface and in which condition the abstract class.
Thanks
Interface vs Abstract Class should be a useful read.
In short, Abstract Classes are meant to be extended, as in you're giving someone a base to work off of. Interfaces ensure that things have a common way of interacting with one another without having to worry about the inside details.
Simple answer: you can implements many interfaces, but can only inherit from one class, so if you want to inherit some logic, you should use Abstract Class, otherwise Interface is more extensible.