• RELEVANCY SCORE 6.18

    DB:6.18:Abstract Class 13




    Difference between abstract class and interface
    use of abstract class

    DB:6.18:Abstract Class 13

    This question has been asked here about a billion times:

    http://search.java.sun.com/search/java/index.jsp?qt=interfacenh=10qp=st=11rf=0since=country=language=charset=variant=col=javaforums

  • RELEVANCY SCORE 5.49

    DB:5.49:Abstract Class And Interface z1




    What is most important thing about abstract class and interface.

    When to use abstract class and interface.

    DB:5.49:Abstract Class And Interface z1

    The interface is like an agreement where the class
    which implements the interface promises to write the
    implementation code for all the functions in the
    interface.Same for an abstract class, only, rather than "all the methods" it's "all the abstract methods." Of course, you could turn around and usethat wording for interfaces too, but in that case it means "all the methods" since interfaces' methods are all abstract.

  • RELEVANCY SCORE 5.32

    DB:5.32:Abstract Class And Interface 18




    what is the difference between abstract class and interface

  • RELEVANCY SCORE 5.32

    DB:5.32:Difference B/W Abstract Class And Interface mf


    Hi,
    can anyone tell the difference between Abstract class and an Interface?

    Thanks in advance!

    DB:5.32:Difference B/W Abstract Class And Interface mf

    The majoor diiffernce is that Interface canot ber
    inherited while absract calss can be inherited
    one abract class can iheret other abstract class
    while Interface doesnot???

  • RELEVANCY SCORE 5.32

    DB:5.32:Concrete Classes Implement Abstract Class And Implements The Interface d9


    I have one query..
    In java collection framework, concrete classes extend the abstract classes and implement the interface. What is the reason behind extending the class and implementing the interface when the abstract class actually claims to implement that interface?

    For example :
    Class Vector extends AbstractList and implements List ,....
    But the abstract class AbstractList implements List.. So the class Vector need not explicitly implement interface List.

    So, what is the reason behind this explicit definition...?

    If anybody knows please let me know..

    Thanx
    Rajendra.

    DB:5.32:Concrete Classes Implement Abstract Class And Implements The Interface d9

    Why do you post this question again? You already asked this once in another thread and it has been extensively debated in that thread: http://forum.java.sun.com/thread.jsp?forum=31thread=347682

  • RELEVANCY SCORE 5.30

    DB:5.30:When To Use Abstract Class And Interface In Project Of Student Management 3j


    Can anyone explain me briefly Abstract Class and Interface
    In Project Of Student Management which class use as a Abstract class .

    DB:5.30:When To Use Abstract Class And Interface In Project Of Student Management 3j

    If it's a program you use you should post this question on the support forums of the program.

    Eyal (http://shilony.net), Regards.

  • RELEVANCY SCORE 5.12

    DB:5.12:Abstract Class And Interface 1d


    Hi,

    What is the diff betw an abstract class and interface and in what situtations can i use abstract class and in what situations can i use interface.
    Please can any one help me.

    DB:5.12:Abstract Class And Interface 1d

    Also a class can only extend one abstract class, but it can implement multiple interfaces. You can also do both at the same time, but you can never extend more than one abstract class

  • RELEVANCY SCORE 4.94

    DB:4.94:Why Interface?Differnce Between Interface And Abstract Class d3


    why we go for interface? what is the difference between interface and abstract class?

    can anyone plz explain with clear picture.

    DB:4.94:Why Interface?Differnce Between Interface And Abstract Class d3

    Look at his profile. He's nothing but a homework dumper anyway. Someone to be ignored.

  • RELEVANCY SCORE 4.91

    DB:4.91:Interface/Abstract Class Explanation? km


    Hi,
    what is abstract class and interface? In which situation we use these ? why we use these? any body explain in detail and with sample

    DB:4.91:Interface/Abstract Class Explanation? km

    http://msdn.microsoft.com/en-us/library/scsyfw1d(v=vs.71).aspx
    Interfaces:
    You have a Business Logic Layer that has classes/objects, and it has reference to a Data Access Layer that has classes/objects that will be called by the BLL objects. The DALclasses/objects can implement an interface, a contract between the called
    and calling objects as to what public properties and methods are exposed on the called object that the calling object can see and use.

    That's what can interface is about.
    http://polymorphicpodcast.com/shows/mv-patterns/
    If you want to see interfaces in action, the view the show on the Presenter and the Service Layer.
    http://www.codeproject.com/Articles/6118/All-about-abstract-classes
    Abstract:
    I have never had to create one, but I have used them in 3rd party frameworks like the CSLA framework that has abstractclasses that can be derived from and used, as base classes.

  • RELEVANCY SCORE 4.90

    DB:4.90:Abstract Class Needs To Implement Interface ms


    Hello, I have an interface and base abstract class defined as follows: interface IbusinessInterface{    void DoSth1();    void DoSth2();    void DoSth3();    void DoSth4();    void DoSth5();    ...    ...    void DoSthN();}public abstract class BaseClass : IBusinessInterface{    public abstract void DoSth1();    public abstract void DoSth2();    public abstract void DoSth3();    public abstract void DoSth4();    public abstract void DoSth5();    ...    ...    public abstract void DoSthN();} what is the reason that this abstract class needs to have methods of the interface implemented  ?Thanks, Michal

    DB:4.90:Abstract Class Needs To Implement Interface ms

    Look at the other side of the coin!  Think interface contract.  The abstract base class is NOT defining any default implementation for you.  Now, when you browse the abstract class you can SEE the member methods that are or not implemented without having to look any further.  Also, when the members of the abstract class are declared as abstract the IDE can generate method stubs for you automatically!  That does not happen if they are declared as virtual.

    Mark the best replies as answers. Fooling computers since 1971.

  • RELEVANCY SCORE 4.88

    DB:4.88:Abstract Class sj


    hello

    why cant we create an object to Abstract class and interface ?
    And if we cant create object how can we can create reference variables to both abstract and interface?

    DB:4.88:Abstract Class sj

    kirn291 wrote:
    how can we can create reference variables to both abstract and interface?I can create a variable of type List (interface), like so

    List _myList = new LinkedList();

  • RELEVANCY SCORE 4.87

    DB:4.87:Diff. Between Interface And Abstract Class 8j


    hi,
    Can any one tell me about diff between interface and abstract class in practical way.advanced thanks for ur response.
    -PVMVS

    DB:4.87:Diff. Between Interface And Abstract Class 8j

    An interface is a way to specify a set of abstract methods that you want a class to implement. The big deal is that the compiler will check that the methods are in fact provided by the class.

    Interfaces almost always represent a view that has nothing to do with the class hierarchy. It could for example be a specific way to access data, like an iterator. Iterators have seldom anything to do with the logical class design. It's just a common way to iterate through the elements of any class.

  • RELEVANCY SCORE 4.87

    DB:4.87:Re: Interface m8


    Java Glossary : interface vs abstract class
    Abstract classes vs. interfaces: When does it make sense to choose an abstract class over an interface?
    Abstract classes and interfaces practicum: Move from theory to practice on when to employ abstract classes vs. interfaces
    Tech Tips: ABSTRACT CLASSES VS. INTERFACES

    DB:4.87:Re: Interface m8

    I'm still entertained by the fact that some folks will
    spell out words like "multiple", "inheritance",
    "interface", and "implement", but not "because".

    :o)LOL!

    This kills me - just bcuz.

    %

  • RELEVANCY SCORE 4.84

    DB:4.84:Abstract Class And Interface Having Same Method fa


    Hello,

    Here is my problem. Suppose we have one abstarct class and one interface.Here is code-
    //Abstarct class
    abstract class X{
    abstract void myMethod();
    }

    //Interface
    public interface Y{
    abstract void myMethod(){}
    }

    Now i have a class which extends both abstarct class X and interface Y.
    If i call myMethod() from this class. Whose myMethod would be called.Will it be of abstract class or interface?
    Many Thanks

    DB:4.84:Abstract Class And Interface Having Same Method fa

    Oops, last part should be

    Now, let's pretend the abstract class above did have code in it.
    //Abstract class
    abstract class X {
    void myMethod() { System.out.println("Hello"); }
    }
    Then, you wouldn't have to have a myMethod() implementation in your class which extends X and implements Y (it's defined in X). If you didn't have one, the method in X would run. If you defined your own myMethod() implementation in your class (which extends X and implements Y), then your own implementation would run.

  • RELEVANCY SCORE 4.83

    DB:4.83:Interfaces And Abstract Classes ck


    Hello,

    I am confused between an Interface and an abstract class. I would cite an example:

    I consider various shape objects esp. square, rectangle etc. and consider a common behavior area which I need to determine for each of these shapes. Should I consider an Interface or an abstract class and why?

    DB:4.83:Interfaces And Abstract Classes ck

    Hint: Interfaces say what objects must do; abstract classes say (partially) how to do them (i.e., it can provide implementations).

    Two shapes are circles and squares.

    To what extent do you think you'll reuse an area() calculation between them?

  • RELEVANCY SCORE 4.83

    DB:4.83:Abstract Class Vs Interface ? 9d


    hi all,

    can anybody help me.

    if i have an abstract class (full of abstract method definitions) and an interface(having same definitions).

    Now the question is in which situation we go for an ABSTRACT CLASS with full of abstract method definitions and in which situation we go for an INTERFACE.

    and other differences between ABSTRACT CLASSES and INTERFACES except Multiple Inheritence ?

    DB:4.83:Abstract Class Vs Interface ? 9d

    Hi,
    All the variable inside the interface are static and final(You can't change it).While in case of abstract class it is not so. And in abstract class you can have concrete method also while in interface all the method must be non concrete So its depends on your requirement.

    Regards,
    Alok

  • RELEVANCY SCORE 4.83

    DB:4.83:Difference Between Interface And Abstract Class a1


    Hi sirs,

    Give me the differences between interface and abstract class
    and when we go for interfaces and abstract class in developing an application

    DB:4.83:Difference Between Interface And Abstract Class a1

    An interface is a 100% abstract class, which means it doesn't contain any code, just method names and signatures. You use abstract classes when you want some code to be shared among the inheritors.

    The advantage with interface is that a class can implement as many interfaces as you like, while it can only extend one (abstract) class.

    So, you use interfaces when you need to extend other classes or doesn't want any code shared, and abstract classes when you don't want to extend other classes, and would like to share some code.

  • RELEVANCY SCORE 4.83

    DB:4.83:Abstract Class z3



    Hi to all,

    can any one tel me what are abstract classes and what hapens if i check the ABSTRACT ckeck box while creating a interface in se24(class builder)?

    Thanks Regards

    Priya

    DB:4.83:Abstract Class z3


    Thanks Matthew .

    Thanks Regards

    Priya

    Edited by: priya latha on Dec 19, 2007 11:43 AM

  • RELEVANCY SCORE 4.83

    DB:4.83:What Is The Difference Between Abstract Class And Interface ? dd


    Hi,

    Could u plz tell me the difference between Abstract class and Interface?

    Thanks in advance.

    Gopi

    DB:4.83:What Is The Difference Between Abstract Class And Interface ? dd

    Lots.

    An abstract class can contain some method implementations, or indeed all the method implementations. It may contain methods with all the various access modifiers. It cannot be instantiated. A class may inherit from only a single abstract class.

    An interface contains only public method stubs and constants. A class may implement multiple interfaces. An interface cannot (obviously) be instantiated.

    Abstract classes are particularly useful when you need to provide a semi-complete implementation for reuse. Interfaces are used more like types.

    Look at java.util.* for some good examples of the use of both.

  • RELEVANCY SCORE 4.83

    DB:4.83:Difference Between Inheritance And Abstract Class 9s


    difference between inheritance and abstract class

    DB:4.83:Difference Between Inheritance And Abstract Class 9s

    There was never an episode of Blackadder where he tried to con his aunt out of an abstract class

  • RELEVANCY SCORE 4.81

    DB:4.81:Abstract Class Inheriting Another Abstract Class ck


    If I have an "Abstract" class that has the following methods:

    Abstract A
    getX();
    abstract getY();
    abstract getXY();And, another "Abstract" class that "INHERITS" A:

    Abstract B extends AWill the "Abstract" methods in class A be ALSO "Abstract" in class B?

    Thanks.

    DB:4.81:Abstract Class Inheriting Another Abstract Class ck

    Think about it: the alternative would be they are no longer abstract methods -- so where did their mystery bodies come from?

  • RELEVANCY SCORE 4.81

    DB:4.81:Diference Between Abstract Class And Interface cp



     
    Hi,
     
    I had a doubt on basic concept of interface and abstract class.
     
    I had idea of wht is interface and abstract class but there is case ,can any do justification on these case is
     
    Abstract class is a clas where some methods r defined and some are abstract methods.
    Interface is where all methods are abstract .
     
    but what happen if i try to maintaince all methods in abstract class as abstract which is equivalent to interface.?
     
    We go for abstract class if want to extend functionality of class.For interface if we wanna implement a new implementation.
     
    is there any other difference apart from this and other issues if we try to have all methods abstract .
     
     
    With regards
    Mahender

    DB:4.81:Diference Between Abstract Class And Interface cp

    Hi,
     
    Thnx for giving info.Actually iam looking for projct development point of view..In whihc cases i do go 4 developing abstract classes  other interfaces

  • RELEVANCY SCORE 4.81

    DB:4.81:When Would You Use An Abstract Class Versus Interface ? zc


    Hi guys

    When would you guys use an Abstract Class versus and Interface ?

    Stev

    DB:4.81:When Would You Use An Abstract Class Versus Interface ? zc

    Another important distinction: declaring functions abstract in a base class not only forces the programmer to implement the function, but also allows messages to be routed to the implemented version.

    Given the shape example from before, the getArea call only works because abstract tells the compiler "hey look for a function prototype that matches this in the derived class"

  • RELEVANCY SCORE 4.77

    DB:4.77:Interface ck


    Can u Explain me the defintion for interface, abstract class

    DB:4.77:Interface ck

    From the Java Tutorial:
    Interface: http://java.sun.com/docs/books/tutorial/java/interpack/interfaces.html
    Abstract Class: http://java.sun.com/docs/books/tutorial/java/javaOO/abstract.html

    Main tutorial page: http://java.sun.com/docs/books/tutorial/index.html

  • RELEVANCY SCORE 4.76

    DB:4.76:Interface Vs Abstract Class d8


    when do we need interface and when abstract class?

    DB:4.76:Interface Vs Abstract Class d8

    2.All the abstract methods must be overrided and
    implemented by the child class.by definition, you can't override a method that has no implementation

    3.Real Examples:

    when we implement the ActionListener interface for
    Button click event then we have to override the
    actionPerformed method, we dont have any other
    chices, so it is a way of forcing the inherited class
    to override certain methods.as before, we implement an abstract method. you're not forcing an override, this can't be done, nor would it be a good idea. as discussed at length recently :-)

    n java you can see all the classes that starts with
    Abstract is abstract.not so. there's nothing at all to stop you writing a concrete class named AbstractClass

  • RELEVANCY SCORE 4.72

    DB:4.72:Abstract And Interface? cm


    why do we need abstract class?
    why do we need interface in java?

    DB:4.72:Abstract And Interface? cm

    Oh please, do some research of your own.

  • RELEVANCY SCORE 4.71

    DB:4.71:Core Java 83


    what is differernce between abstract class and interface?

    DB:4.71:Core Java 83

    jwenting wrote:
    maybe an attempt at counting only posts which make any kind of sense at all?Where did the '1' come from then?

  • RELEVANCY SCORE 4.67

    DB:4.67:Interface And Abstract cp


    hi everyone
    may i knowreal timescenario
    whichsituation we used abstract class and which situation we use interface in project developing

    paritala.ramanjaneyulu

    DB:4.67:Interface And Abstract cp

    Wrong forum ! You can post a question at http://social.msdn.microsoft.com/Forums/en-US/whatforum/threads to find the best place to ask your question.

    Regards. --Ismet

  • RELEVANCY SCORE 4.67

    DB:4.67:Difference Between Abstract Class And Interface ? fz


    CAN ANY BODY TELL ME THE DIFFERENCE BETWEEN THE ABSTRACT CLASS AND INTERFACE ?

    DB:4.67:Difference Between Abstract Class And Interface ? fz

    - An abstract class is a class that can not be instantiated but that can contain code, i.e. it gives you the ability to specify default implementations of methods.

    - An interface only contains methods but does not contain any code and you need to implement all the methods defined in the interface.
    - Interfaces may be multiple-inherited, abstract classes may not
    http://www.codeproject.com/Articles/11155/Abstract-Class-versus-Interface
    http://stackoverflow.com/questions/56867/interface-vs-base-class

  • RELEVANCY SCORE 4.66

    DB:4.66:Difference ???? xz


    What's the difference between an Interface and Abstract class ??????

    DB:4.66:Difference ???? xz

    Is google broken again?
    [http://www.google.co.uk/search?q=What's+the+difference+between+an+Interface+and+Abstract+class] 652,000 hits

  • RELEVANCY SCORE 4.66

    DB:4.66:Abstact Class And Interface s9


    Hi,

    Any One Can Let me know the exact diff. Between the Abstract class and Interface.

    With
    BAbu

  • RELEVANCY SCORE 4.66

    DB:4.66:Regarding The Abstract And Interface km


    hai,
    I am new to java programming

    I want to difference between abstract interface,interface and abstract class

    public abstract interface Test{}

    public interface Test{}

    public abstract class Test{}

    which kind of situations use the above interfaces and abstract classes

    It would be helpfull if explain with example....

    Thanks

    DB:4.66:Regarding The Abstract And Interface km

    shashikumar, please don't multipost and don't use the browser's back button to edit your post. This creates multiple posts. I've removed the other thread you started a minute after this one.

    db

  • RELEVANCY SCORE 4.66

    DB:4.66:Abstract Class And Interface x7


    Hi,
    Can anyone explain why we use abstract class and interface
    and when we use abstract class and interface
    and which one is best to use
    please explain in simple words
    waiting for reply.....

    DB:4.66:Abstract Class And Interface x7

    Abstract classes and interfaces are very similar. In languages that support Multiple Inheritance (like native C) abstract classes are what is used for/instead Interfaces.
    Allas, Multiple Inheritance is a ugly thematic (for the guy who writes Compilers and for the programmer that writes the code). And hence the developers of .NET decided:
    A class can only inherit from on base class. For everything else, use interfaces. (they propably took that directly from Java) It is not the worst decision by the way, Polymorphy with Multiple Inheritances really is a headache (1-2 chapters in each C
    book).

    The differences are:
    A abstract class has to be in the Inheritance Chain.
    A abstract class can code out any functions and methods it defines. This includes (even if that may sound contra-intuitive) the Constructor (it is to be called using base()). It does not have too.
    A abstract class can define public Varriables. But with the advent of properties (wich are short syntaxes for Functions), this became mostly irrellevant.

    A Interface can't be part of the Inheritance Chain (but in a way Interfaces can inherit other interfaces, creating Interface chains).
    A interface can't code out any functions. It can only provide the signature (name, parameter types, return type).
    As properties are little more then a neat way to write get- and set-functions, a Interface
    can contain properties.
    What they have in similar:
    Neither can be instantiated.
    Both can be used as Varriable types (so it does not matter wich implementation of this Interface/A-Class you have). Indeed downcasting to the Abstract or Interface type is what you most often see them used for.
    Both force class that Inherit/Implement them to provide code for the Functions. You don't need to know how a IComparable figures out wich Instance is higher then the other. Nor how exactly a SQLConnection opens the Connection. You only need to know is has
    a Compare() and Open() Function respectively.
    When to use Abstract classes:
    You want thsi thing to be part of the Inheritance Chain.
    You want this Functionality to be the main job of whatever inherits from it. Example:
    DBConnection. The abstract baseclass of things like SQLConnection. The designers decided that a DBConnection should not also be a Window/Form. A DBConnection should be
    created for it's specific task (connecting to a DB), be used and then be thrown away (or in this case Diposing would be even better). Allowing it to be also a Window would only risk keeping it in memory to long wich can be uggly as it uses unmanaged resources.
    A similar example is
    Stream, the baseclass of FileStreams, memoryStreams and the like. You will find this often whenever dealing with input/umnaged resources.

    When to use Interfaces:
    Everytime you don't need an Abstract class. Or even the other way: Only use abstract classes is you really need them/want them.

    Interfaces are ideal for small functionality. For example,
    IComparable. When a class implements IComparable it can be sorted by the .Sort() function of a list. Yet, being sortable is not the main function of this class. It's job is propably to contain multiple data fields as a unit. Being sortable is just a small
    functionality to be added. But as long as this functionality is added by providing Code for IComparable.Compare(), it can be sorted! The writer of List did not need to know how it works. Just the return values are of interest.Let's talk about MVVM: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/b1a8bf14-4acd-4d77-9df8-bdb95b02dbe2

  • RELEVANCY SCORE 4.66

    DB:4.66:Difference % Abstract Class And Interface? d3


    Hi,

    I am confused about abstract class and interface. For interface, the subclass has to implement all the parent class methods. But, it is no need in abstract class.

    However, in which situation should I use abstract class or interface?

    Thanks for explanation.

  • RELEVANCY SCORE 4.64

    DB:4.64:Interface 38


    Helo Sir,
    Iam sreedhar.L.
    I hope you will solve my doubt.
    This is my doubt...
    I have a abstract class ,i coded
    2 concrete methods(Implemented methods) and
    3 abstract methods.
    Now,
    why we have abstract class extra...
    just we can put the concrete methods in normal class and abstract methods in interface.
    why we need this extra abstract.
    please tell me
    thanks in advance

    DB:4.64:Interface 38

    This question, or one like it, has been asked many, many times. Try using google or this website's search function.

    The very short version: interfaces are used for defining a pure type, with no implementation. Abstract classes can do that, but are better suited for when you have a reasonable default implementation for some methods that you expect some subclasses to use.

  • RELEVANCY SCORE 4.62

    DB:4.62:Java Interfaces And Abstract Classed fc


    what is the difference between interface and abstract class?

    DB:4.62:Java Interfaces And Abstract Classed fc

    I suggest you try writing some code and see.

  • RELEVANCY SCORE 4.57

    DB:4.57:Difference Between Interface And Abstract Class 71


    I'm confused on what is the difference of implementing n abstract class and inheriting an interface?

    DB:4.57:Difference Between Interface And Abstract Class 71

    Hi,
    i want to add a few more differences --
    1.The variable defined inside an interface is public, static and final means it's basically a constant,But in case of abstract class you can hide the variable in the implementation class means you can change the value of the variable.

    One very important thing about the these two feature is when to use what?
    Ans:If a group of object is having some common property such that they are not going to be changed over a period then create an Abstract class out of that property.But if only some object is having a common property but not all then create an interface out of that property and implement all that property in Subclass.

    Thanks.

  • RELEVANCY SCORE 4.57

    DB:4.57:Interface Or Abstract Class 1k


    Hi all, I am not sure when should I go for an interface and when should I go for an abstract class(both are abstractions ultimately)? Can anyone please give instance(s) where I should use an interface and not an abstract class and vice versa? Regards, Sandip

    DB:4.57:Interface Or Abstract Class 1k

    Hi TimJim,Thanks for your insight. I think even the following link is also quite good -http://social.msdn.microsoft.com/Forums/en-US/vblanguage/thread/511cce83-3b58-495d-8198-1df8bdc49fd0/Regards,Sandip

  • RELEVANCY SCORE 4.55

    DB:4.55:Urgent Please 81


    Hi,

    What is the diff betw an abstract class and interface and in what situtations can i use abstract class and in what situations can i use interface.
    Please can any one help me.

    DB:4.55:Urgent Please 81

    Thank you very much sir,
    Now you gave nice explanation.
    Now i am clear with interface and abstract class.

    If you don't mind may i ask one more question.

    Please can you tell me

    what is the diff betw HashTable, HashTree and HashMap.

  • RELEVANCY SCORE 4.50

    DB:4.50:Abstract Class Vs Interface 9d


    Hi

    I was just wondering what is the advantage of using an abstract class over interface. In what situation, using an abstract class is more suitable than using interface? and vice versa?

    DB:4.50:Abstract Class Vs Interface 9d

    This question has been asked and answered a million times. For instance, see this thread: http://forum.java.sun.com/thread.jsp?forum=31thread=352322

  • RELEVANCY SCORE 4.48

    DB:4.48:Abstract Class And Interface Use 1k


    hi

    i am asking some stupied questions. plz can any one tell me

    1) what is interface and abstract class ? one example?
    2) when do u go for interface and when do u go for abstract class?
    3) what is exact difference between abstraction and encapsulation?

    thanks in advance

    DB:4.48:Abstract Class And Interface Use 1k

    Mahaboob wrote:
    hi

    i am asking some stupied questions.I agree.

    plz can any one tell meHere's a much better idea. You go do some basic research on these questions which have been asked 1,000,000,000 times previously and then tell us what you think. Then we can have a lively discussion about your ideas.

    'kay?

    And just to get you started in the right direction here's something you can review that will answer part of or all of your questions [_http://java.sun.com/docs/books/tutorial/java/index.html_|http://java.sun.com/docs/books/tutorial/java/index.html]

  • RELEVANCY SCORE 4.47

    DB:4.47:C#: What Is Difference Between Abstract Class And Interface? How To Decide To Use Which One? 18


    I have been asked a question: how to decide to use Abstract class or Interface?
    We know that the Interface is special Abstract. All definitationsare default public and without implemetion. Classed inherit from interface has to implement all definitions.

    Abstract class does not need to implement all the methods and it can not be instantiated.
    Classes inheritfrom abstract classmay sharecommon logic (properties or methods) with abstract class and also override some methods' behavior.
    How to clearily answer this question? Thx!

    JaneC

    DB:4.47:C#: What Is Difference Between Abstract Class And Interface? How To Decide To Use Which One? 18

    Hello JJChen,
    Interface class can be implement in small units of data but abstraction class can be implemented in large units of data.
    1. Here is explanation of
    Interface class
    2. Here is explained
    Abstraction class.
    3.
    Difference betweenAbstraction andInterface class.
    Hope it will help you a lot.
    thanks,

  • RELEVANCY SCORE 4.45

    DB:4.45:Difference Between Interface And Abstract Class? x1


    Hi,

    Can u plz explain
    at what scenarios we use interface and abstract class.?

    Thanks,
    B.Maruthi

    DB:4.45:Difference Between Interface And Abstract Class? x1

    If you had read the FAQ at the top of the forum home
    page you wouldn'y have bothered to ask this
    question.Anyways heres the link

    Read the question number 13 in this link

    http://access1.sun.com/FAQSets/newtojavatechfaq.htmlnice

  • RELEVANCY SCORE 4.42

    DB:4.42:Differance Between Abstract Class And Interface 7s


    Whats the main differance between abstract class and Interface and where I can use abstract class and where I can use Interface

    DB:4.42:Differance Between Abstract Class And Interface 7s

    Refer to
    http://www.javaworld.com/javaworld/jw-09-2001/jw-0921-interface.html

  • RELEVANCY SCORE 4.36

    DB:4.36:Abstract Class Vs Interface 1x


    Hi I have a small doubt regarding this.
    When can i go for Abstract Class and When can i go for Interface.
    Anybody can help me?

    DB:4.36:Abstract Class Vs Interface 1x

    Hi I have a small doubt regarding this.
    When can i go for Abstract Class and When can i go for Interface.
    Anybody can help me?

  • RELEVANCY SCORE 4.36

    DB:4.36:When Should I Use Abstract Class And When I Should I Interfaces x8


    when should we use abstract classes over interface or vice versa;i am getting this question regulary;how should i give proper answer.

    whatever methods we define in abstract class same thing we can do in interfaces;

    so what we can achieve with abstract class;

    with regds
    chaitanya

    DB:4.36:When Should I Use Abstract Class And When I Should I Interfaces x8

    You can implement multiple interfaces. You can only inherit from one abstract class.

    Abstract classes can implement some methods (and define others abstract).

    Abstract classes can have fields that get inherited, interfaces can't.

  • RELEVANCY SCORE 4.36

    DB:4.36:Difference 7x


    Hi sirs,
    Give me the main differences between abstract class and interface.Dont give me the links sir,

    when we go to use for the interface and for abstract class in developing an application

    DB:4.36:Difference 7x

    Another link:
    {color:#0000ff}http://forum.java.sun.com/thread.jspa?messageID=9961601{color}

    db

  • RELEVANCY SCORE 4.36

    DB:4.36:When To Use Abstract Class And Interface? jp


    hi,

    When to use Abstract class and Interface?

    DB:4.36:When To Use Abstract Class And Interface? jp

    Thanks for all, i got some clear idea about when to use interface and abstract class.

  • RELEVANCY SCORE 4.35

    DB:4.35:What Is The Difference Between Abstract Class And Interface af


    hi,recently i went for an interview they ask me what is abstract class ,interface and its difference
    I said abstract class contain abstact method ,abstract method is a method with no body.Abstract class cannot be instantiated.Abstract class is a base class it required derived class for the implementation of method.
    Interface is a syntactical contract that all derived class should follow
    it define properties ,method,events which are known as member of interface.
    Then They asked me what is the difference between them. I said
    abstract class interface
    1.abstact class can implement method 1.interface cant
    2.abstact class can contain constructor, 2.interface cant
    destructor
    3.abstract class cannot support multiple 3.interface support
    inheritance
    etc
    Then they said some different answer I said dont no.
    Then they ask me when i should make abstract class for an project and when
    i should make interface.
    I said if suppose there is two class which must be having method with different logic then we sholud make abstract class.
    and if suppose we have two class having method .with different logic then we can make interface .
    Am i correct with my explaination.if not correct me .please provide me that when should we create abstract class and interface and what is difference .please help me

    DB:4.35:What Is The Difference Between Abstract Class And Interface af

    I would focus the answer on the distinction that you cant add an abstract class to an existing class like you can an interface.

  • RELEVANCY SCORE 4.35

    DB:4.35:Interface 9f


    In which situation u will use an interface and abstract class

    Edited by: sb125 on Nov 16, 2007 3:04 AM

    DB:4.35:Interface 9f

    sb125 wrote:
    In which situation u will use an interface and abstract classHere's a situation in which u will use an interface and an abstract class:

    class u extends AbstractList implements Serializable {
    //functionality
    }

  • RELEVANCY SCORE 4.35

    DB:4.35:Nested Interfaces And Abstract Methods zx



    Consider the following design:

    interface ZIF_INTERFACE_A.
    methods METHOD_A.
    endinterface.

    interface ZIF_INTERFACE_B.
    interfaces ZIF_INTERFACE_A.
    methods METHOD_B.
    endinterface.

    class CLASS_A_B definition abstract.
    public section.
    interfaces ZIF_INTERFACE_B
    abstract methods METHOD_B.
    interfaces ZIF_INTERFACE_A
    abstract methods METHOD_A.
    methods METHOD_C.
    endclass.
    class CLASS_A_B implementation.
    method METHOD_C.
    endmethod.
    endclass.

    DB:4.35:Nested Interfaces And Abstract Methods zx


    No, you don't have to manually do this while defining a similar global class. The class builder automatically maintains the order of the definition!

    Actually, I did have to do that. The class builder declared the interfaces in the wrong order.

    I only wrote the local classes to demonstrate the problem on this forum.

  • RELEVANCY SCORE 4.35

    DB:4.35:Interface And Abstract Class dc


    why we have constructor for abstract class and not for interface,

    DB:4.35:Interface And Abstract Class dc

    Simpler reason: interfaces have no implementation. Period.

  • RELEVANCY SCORE 4.35

    DB:4.35:Interface Vrs Abstract Class ps


    why would i during design choose for an interface or an abstract class. I cant understand the need for both ?

    To make a class a partially implemented, its has to be abstract.
    I can choose to create a complete Interface heirarchy and simulate the same.........

    Can people clarify why Interface and why abstract.

    Ps: I know difference between both but I want to justify myself why I wud go for abstract class or interface

    Looking for ur inputs

    DB:4.35:Interface Vrs Abstract Class ps

    why would i during design choose for an interface or
    an abstract class.If there was no abstract you would have to use overriding to accomplish the same thing. But abstract is stronger because you clearly state your intention of leaving the implementation to a subclass. Overriding isn't enforced, the subclass always has a choise. In short, using abstract the superclass rules, using overriding the subclass rules.

    So the big deal is when to use abstract and when to use overriding. Interfaces don't have anything to do with that! Interface are used when you want to ensure a class has a certain functionality that is not a natural part of the normal class hierarchy. It's often a common way to access data, like for example iteration.

  • RELEVANCY SCORE 4.34

    DB:4.34:Interface And Abstract Class ad


    Why can't we declare a static method in Interface but it's possible in abstract class?

    DB:4.34:Interface And Abstract Class ad

    Because an interface is simpler than an abstract class.
    Normally you would put a static method like this into a utility class with a private constructor. see the Math class.

  • RELEVANCY SCORE 4.34

    DB:4.34:Abstract Class And Interface 33


    When we have got is the interface then do you need is an abstract class? ....since i can divide an abstract class to two one is interface and the other a concrete class.....So where is the exact functionality of an abstract class.
    Why is that a file name should be the same as that of the public class declared in that file?

    DB:4.34:Abstract Class And Interface 33

    Why is that a file name should be the same as that of the public class declared in that file?Because that's what is required by the JVM.

  • RELEVANCY SCORE 4.34

    DB:4.34:Difference Between Interface And Abstract Class mj


    hello friends give me the difference between interface and abstract class
    and link to find java material

    Thanx

  • RELEVANCY SCORE 4.34

    DB:4.34:Interface &Amp; Abstract Class d3


    1whats the basic difference between an interface and an abstract class?
    when should one be using an interface or an abstract class?

    2whats the difference between method overriding and method overlaoding?
    does both of them has any relation with the instance of te class implementing them?

    DB:4.34:Interface &Amp; Abstract Class d3

    http://www.google.com/search?q=java+interface+%22abstract+class%22

    http://www.google.com/search?q=java+method+overloading+overriding

  • RELEVANCY SCORE 4.34

    DB:4.34:What Is The Difference B/W Abstract Class And Interface j9


    Hi everybody!
    I'm little confused abt the difference b/w abstract class and interface. Plz help me in this regard.
    Bye
    Mustafa

    DB:4.34:What Is The Difference B/W Abstract Class And Interface j9

    You've got a lot of postings describing the semantic differences, here's one that gives you a practical difference: use interfaces to define policy, abstract classes to define mechanism.

    Assuming that got a big "huh?" ...

    An interface defines a set of methods, which I think of as "capabilities." For example, java.util.List defines methods to add/remove/retrieve items to a list. Any object that implements that interface is saying that it has the capability to maintain items in a list. However, it doesn't say anything about how that object is implemented; perhaps it uses an array, perhaps a linked list.

    By comparison, java.util.AbstractList defines at least part of the mechanism used to implement the List interface. It still leaves some of the implementation open to the programmer, but handles a lot of the details common to all lists.

    By keeping this practical definition in mind, I'm not tempted to use an abstract class in place of an interface. Instead, I limit abstract classes to places where there's common implementation -- in other words, they become a refactoring tool.

    One example: as I've started to develop Swing apps, I find that I'm implementing a lot of dialogs. Since I want a common look and feel to my dialogs, there's a lot of code that's common. However, since each dialog has a separate purpose in life, there's also a lot that differs. So I implemented an AbstractDialog class that handles common operations such as UI decorations.

    Now, I could have implemented this as an instantiable class, which would have methods that are overridden by subclasses. But I went with an abstract class for two reasons: (1) there's no reason to instantiate the base dialog, and more important, (2) by defining certain methods as abstract, I force the subclass into providing implementations, thus eliminating bugs due to laziness.

    One last comment: this example defines very little in the way of policy, so it's clearly a candidate to be an abstract class. You may wonder what to do about objects that aren't so clear, but I've found that there are very few of these. In my version of a good OO design, objects either define policy or mechanism, but almost never both.

  • RELEVANCY SCORE 4.34

    DB:4.34:About Interface In Java 7z


    what is basic idea behind the interface and abstract class

    DB:4.34:About Interface In Java 7z

    Search in this forum. You will find lot of threads discussing the same topic.

  • RELEVANCY SCORE 4.34

    DB:4.34:Can Anyone Share The Real Time Example With Explanation For Abstract Class And Interface? kk


    Real time examplefor Abstract class ?

    DB:4.34:Can Anyone Share The Real Time Example With Explanation For Abstract Class And Interface? kk

    Hi
    Actually this is vary old school days debate but in today`s worlds it is of no use ,latest design principles says that Program to Interface
    , Let me explain more

    Abstract Class

    Use abstract class when the entity it represent doesn’t exist in real world , for example Shape itself has no meaning , It is pure conceptual so
    you should go for abstract implementation
    Interface

    It is more restricted form of abstract class and always recommended
    Interface Vs Abstract class

    Use interface when you do not have anything to share in base class Use Abstract class of there are some function that will be share across all derived object Always prefer Interface
    Best design Approach

    Best Design approach is to use mix of both i.e. Interface AbstractConcrete , See the share Example below that is very simplified version.

    Hope it help

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using Microsoft.Practices.EnterpriseLibrary.Logging;

    namespace LoggerSample
    {
    interface IShape
    {
    void Render();
    }

    abstract class Shape : IShape
    {

    public virtual void Render()
    {
    Console.WriteLine(Default Drawing, Empty Box);
    }
    }

    class Default : Shape
    {
    // No implementation for IShape.Render()
    }
    class Circle : Shape
    {
    public override void Render()
    {
    Console.WriteLine(Drawing Circle);
    }
    }
    class Rectangle : Shape
    {
    public override void Render()
    {
    Console.WriteLine(Drawing Rectangle);
    }
    }
    class Program
    {
    static ListIShape MyShapes = new ListIShape();
    static void Main(string[] args)
    {
    MyShapes.Add((IShape)new Default());
    MyShapes.Add((IShape) new Circle());
    MyShapes.Add((IShape) new Rectangle());
    MyShapes.Add((IShape)new Rectangle());
    MyShapes.Add((IShape)new Rectangle());
    MyShapes.Add((IShape)new Circle());

    RenderMyShapes(MyShapes);

    Console.ReadLine();
    }

    public static void RenderMyShapes(ListIShape MyShapes)
    {
    foreach (IShape shape in MyShapes)
    {
    shape.Render();
    }
    }
    }
    }

  • RELEVANCY SCORE 4.34

    DB:4.34:Difference B/W Abstract Class And Interface dx


    hi friends,

    can anyone plz divulge the differences between abstract class and interface and under what situations can we use these concepts.

    thanks

    madhusudan.D

  • RELEVANCY SCORE 4.34

    DB:4.34:What Is The Different Between Abstract An Interface Class? jf


    what is the different between abstract an interface class?
    and
    What is the different between access specifier of public and friendly.

    DB:4.34:What Is The Different Between Abstract An Interface Class? jf

    what is the different between abstract an interface
    class?interfaces contain only signatures of method you'll have to implement and constant
    whereas abstract classes contains method implemented and/or method non implemented

    What is the different between access specifier of
    public and friendly.the scope of 'friendly' is the package which contains it

  • RELEVANCY SCORE 4.33

    DB:4.33:Difference Between An Interface And An Abstract Class 9f


    Hey:

    I'm curious, what's the difference between an interface and an abstract class? Thanks.

    DB:4.33:Difference Between An Interface And An Abstract Class 9f

    "You have an abstract class if you want to implement some of the methods in it, but you do not want users to make instances of the class or do not want to implement all of the methods. Take a look at some of the abstract classes in java.util. Nearly all of the methods are implemented already so that it's far easier to create new data structures than if only interfaces were provided. "

    That's what I was looking for. Thanks.

  • RELEVANCY SCORE 4.33

    DB:4.33:Mdb Abstract Base Class And Ejb3 Annotations 1k



    I have following scenario where my MDB class extends an abstract class which implements the MessageListener interface.
    public abstract class MDBBase implements MessageListener {
    public void onMessage(Message message) {
    ....
    processJob(some-params)
    }
    public abstract void processJob (some-params);
    }

    public class MyMDB extends MDBBase {
    public abstract void processJob (some-params) {

    }
    }

    DB:4.33:Mdb Abstract Base Class And Ejb3 Annotations 1k


    I have following scenario where my MDB class extends an abstract class which implements the MessageListener interface.
    public abstract class MDBBase implements MessageListener {
    public void onMessage(Message message) {
    ....
    processJob(some-params)
    }
    public abstract void processJob (some-params);
    }

    public class MyMDB extends MDBBase {
    public abstract void processJob (some-params) {

    }
    }

  • RELEVANCY SCORE 4.33

    DB:4.33:Abstract Class Or Interface. Which One Is Better 77


    hai everybody,

    i have a confusion between choosing of abstract class or Interface.

    abstract class Abstra
    {
    public abstract void abst();
    }
    interface Inter
    {
    public abstract void inter();
    }

    looks almost same !!!
    which one of above is better to inherit for a class.
    and more importantly why ?
    Everybody says it's interface....but i dont understand what could be the reason.
    i want to know the reason if interface is better as compare to abstract class.
    why ? why ? why ? why ?

    DB:4.33:Abstract Class Or Interface. Which One Is Better 77

    a very good answer...get to know first of all whats the difference between Abstract class and Interface.

  • RELEVANCY SCORE 4.33

    DB:4.33:Difference j9


    difference between abstract class and interface

    DB:4.33:Difference j9

    @OP You can see by the blatant obviousness and boring repetitiveness of these answers that this is a frequently asked question.

  • RELEVANCY SCORE 4.32

    DB:4.32:Difference Between Pure Abstract Class And Interface? 89


    hi,
    i just want to know the difference between pure abstract class(as same as interface- no implementation of methods) and interface

    Thanks,

    DB:4.32:Difference Between Pure Abstract Class And Interface? 89

    A very nice and detailed article on this code project link (posted by Magnus).

  • RELEVANCY SCORE 4.32

    DB:4.32:What Is The Main Difference B/W Interface And Abstract Class 83


    is there any specific difference b/w interface and abstract class. if wht is tht? and how?

    DB:4.32:What Is The Main Difference B/W Interface And Abstract Class 83

    abstract class can be have methods with body

    interface cannot

    interface is 100% abstract class

  • RELEVANCY SCORE 4.31

    DB:4.31:Abstract Class And Interface fk


    Hi,
    Can any one explain in simple words
    what is the use of abstract class and interface
    and when we have to use abstract classes and interface
    thanks you

    DB:4.31:Abstract Class And Interface fk

    We use abstract class when their is commonbehavioramong the classes. In order to enforce , some default functionality to classes which are getting derived from the abstract class , use abstract class.
    But Interfaces are use to provide only the contracts for the classes which are not relating to each other. we are enforcing some features to the classes which are implementing the interface , but the implementation varies for the classes.
    Lalit
    Propose it for answer if solves your query.
    Lalit

  • RELEVANCY SCORE 4.31

    DB:4.31:Abstract Class Vs Interface In Term Of Speed pd


    Hi guys,
    I read every whare abstract class are faster then interface because interface require extra in direction. i want to know about how compiler deals with interface and abstract class.
    Thanks

    DB:4.31:Abstract Class Vs Interface In Term Of Speed pd

    hi,gays i think doesn't matter for code speed, we don't live in stone era. The question is what is better solution interface or abstract class.there is my visionThanks in advice

  • RELEVANCY SCORE 4.30

    DB:4.30:Help Me Developers On Interface And Abstract Class zz


    Which is better to use and why in an Application.interface and abstract class
    I am confused onthis topic.

    DB:4.30:Help Me Developers On Interface And Abstract Class zz

    @Sethp45:

    When you post code, please use [code] and [/code] tags as described in Formatting Help on the message entry page. It makes it much easier to read and prevents accidental markup from array indices like [i].

  • RELEVANCY SCORE 4.30

    DB:4.30:Abstract Class And Interface 97


    is it any differences between abstract class and interface?

    DB:4.30:Abstract Class And Interface 97

    And of course you [url http://onesearch.sun.com/search/developers/index.jsp?col=devforumsqp_name=Java+Programmingqp=forum%3A31qt=%22+differences+between+abstract+class+and+interface%22] searched first....

    Mike

  • RELEVANCY SCORE 4.30

    DB:4.30:Abstract And Interface fa


    Dear Sir/Madam,

    Please let me know the difference between Abstract class and Interface.

    DB:4.30:Abstract And Interface fa

    I disappeared as i was checking the forums in javaworld.com, but now i will keep this site as main.

  • RELEVANCY SCORE 4.29

    DB:4.29:Difference Between Abstract Classes Vs Interface 77


    Hi,
    Can u pls mention all the differences between Abstract Classes and Interface.? I've mentioned the differences I've known here.

    Known Differences:
    ------------------
    (*) An interface cannot implement any methods, whereas an abstract class can.
    (*) A class can implement many interfaces but can have only one superclass

    Can U pls mention at what situation(practical situation) we've to go for abstract class or Interface?
    Tell me the situation when we have to go for abstract class?
    Tell me the situation when we have to go for interface?

    Please Reply me
    Thanks Regards
    Venkatesh

  • RELEVANCY SCORE 4.28

    DB:4.28:What Is The Difference Between Abstract Class And Interface jf


    Hi,
    Can you please tell me the differences between Abstract class and Interface.
    In which scenarios we have to use Abstract class and in which scenarios should use Interface.

    Thanks and Regards
    Kranthi

    DB:4.28:What Is The Difference Between Abstract Class And Interface jf

    http://stackoverflow.com/questions/761194/interface-vs-abstract-class-general-oo

  • RELEVANCY SCORE 4.27

    DB:4.27:Abstract Class And Interface 3j


    I would covet to recognize at what situation we use abstract class
    and when to use interface?

    With Regards,
    Stalin.G

    DB:4.27:Abstract Class And Interface 3j

    http://www.google.com/search?q=abstract+class+interface+site:forum.java.sun.com

  • RELEVANCY SCORE 4.25

    DB:4.25:Interface Vs Abstract Class ?? z1


    Are there any guidlines when to use Interface and when abstract class.
    Tried to dig in book but failed. Will appreciated any links.

    Thanks
    Mario

  • RELEVANCY SCORE 4.25

    DB:4.25:Abstract Class 9k



    i know the concept of abstract class in java and this concept is used in interface, i.e all the methods declared in interface are abstract. i want to know how the abtract class is different from the normal class in java

    DB:4.25:Abstract Class 9k

    all the answers you need can be found thru google: "java abstract class"

    http://java.sun.com/docs/books/tutorial/java/IandI/abstract.html

  • RELEVANCY SCORE 4.25

    DB:4.25:Interfaces And Abstract Classes 73


    can anyone pls tell me where exactly an abstract class is used and where exactly an interface is to be used.

    i think the main difference between an abstract class and an interface is that an interface will have all the abstract methods whereas an abstract class can have one or more abstract methods--- if i am not wrong.
    anything to add? -- pls let me know on this....

    and also how they might be useful for us....

    DB:4.25:Interfaces And Abstract Classes 73

    The differences are already quoted. In addition of that
    the abstract class will come in the class/system hierarchy, but interface will not.

  • RELEVANCY SCORE 4.25

    DB:4.25:Re: What Is The Difference Between An Interface And An Abstract Class? 1a


    8000 views already wow.

    DB:4.25:Re: What Is The Difference Between An Interface And An Abstract Class? 1a

    filestream wrote:
    As the two famous politicians, Jonathan Curry and Larry Craig are wont to say, "Glad I could serve you."

    Of course, each says it in entirely different situations but we're not here to discuss that. The members of the forums are happy just knowing that we've cleared 1 doubt.Now that you mention it, I take a wide stance in the interface/abstract class issue.

  • RELEVANCY SCORE 4.24

    DB:4.24:Why Would You Ever Use An Interface Instead Of An Abstract Class? mz


    With an abstract class, you can have unimplemented methods and then implemented methods. With an interface, you can only have unimplemented methods.

    Can somebody tell me, then, why Joe Doe would want to use an interface over an abstract class?

    DB:4.24:Why Would You Ever Use An Interface Instead Of An Abstract Class? mz

    Can somebody tell me, then, why Joe Doe would want to
    use an interface over an abstract class?The main reason is a limitation in the Java inheritance model namely that you can inherit one class only but as many interfaces as you want. This can be characterized as: single inheritance of implementation but multiple inheritance of type. The latter is considered the most important in OO design so the fact that you can inherit implementation from from one source only isn't that much of a limitation really .

    So to make use of multiple inheritance of type in Java you need to use interfaces (and possibly one class).

  • RELEVANCY SCORE 4.24

    DB:4.24:Difference Between Abstract Class And Interface j3


    What is the difference between anabstract class and aninterface ?

    DB:4.24:Difference Between Abstract Class And Interface j3

    Hi,
    Check this link differencebetween an abstract class and an interfacePS.Shakeer Hussain

  • RELEVANCY SCORE 4.24

    DB:4.24:Abstract Class &Amp; Interface 17


    What is the difference between Abstract Class and Interface Class? What I understood is both has to be defined in the subclass i.e methods. Apart from that Interface supports multiple inheritance whereas Abstract class doesn't. When both has to be defined in the subclass and interface supports multiple inheritance why we still need Abstract Class.

    Thanks in Advance,
    R.Ravindhran

    DB:4.24:Abstract Class &Amp; Interface 17

    A class can only extend one other class (Abstract or not) but it can implement any number of interfaces.

  • RELEVANCY SCORE 4.22

    DB:4.22:Abstract Class Vs Interface 9a


    Can somebody please explain to me why we need both abstract classes and interfaces? Don't they serve almost exactly the same role? Besides syntax and the possibility of implementing multiple interfaces, is the only difference that an abstract class is allowed to have non-abstract methods?

    DB:4.22:Abstract Class Vs Interface 9a

    interfaces also may have variables but they have to be declared final. ???

  • RELEVANCY SCORE 4.21

    DB:4.21:Difference Between Abstract Class And Interface 71


    Here is a fresher in Java. Could any body tell me the difference between Abstract Class and Interface. And suppose Abstract class has three methods, in those, two of them are Abstract and one is normal method, and it has been implemented in that class itself. If we extend the Abstract class to our class, do we need to over ride or implement all the methods that are there in the Abstract class or we need to implement only those methods that have been declared as abstract. If it is so, then what is the purpose of implementing non abstract method in the Abstract class.

    Sravan

    DB:4.21:Difference Between Abstract Class And Interface 71

    public abstract class TestAbstract {
    public abstract void method1();
    public abstract void method2();
    public static void method3() {
    // non-abstract method must have a body
    }
    }

    public class TestAbstract2 extends TestAbstract {
    public void method1() {
    // Does not work:
    // Object test = new TestAbstract();
    TestAbstract.method3();
    }
    public void method2() {
    }
    }- you will have to implement all method which are declared as abstract. you do not need to implement method3 in this example., only method1 and method2.
    - an abstract class cannot be instantiated (doesn't work: Object test=new MyAbstractClass())
    - a non-abstract method in an abstract class can be used, if it's a static member.
    - with "extends" you can only have one class, and your class will inherit the members of the superclass
    - with "implements" you can use multiple interfaces, which are only a description of what you have to write yourself...

  • RELEVANCY SCORE 4.19

    DB:4.19:Interfaces And Abstract Classes fk


    hi,

    Can anyone help me regarding the difference between interfaces and abstract classes. What is the advantage of interface over abstract classes and viceversa. Obout the possibities of multple inheritance I know. I found allmost all people are talking some external answers.
    Why an abstract class cant we do it with concrete class.
    regards,

    Jayaprasad Viswanathan

    DB:4.19:Interfaces And Abstract Classes fk

    Abstarct class can never be instantiated. Same as interfaces.

    Can be
    subclassed.Same as interfaces.

  • RELEVANCY SCORE 4.19

    DB:4.19:Diffrence Between A Interface And A Abstract Class? f7



    Hi OO ABAP Gurus

    Please clear below point to me.

    Diffrence between a Interface and a abstract class?

    Many thanks

    Sandeep Sharma..

    DB:4.19:Diffrence Between A Interface And A Abstract Class? f7


    Interface:

    All the methods of the class ARE UNDEFINED. You need to implement the interface in a class and give the method definition now. In other words INTERFACES just have the declarations no definitions.

    Abstract Class:

    All the methods which are defined for the class may have the definition or may not. Say we have 3 methods defined for this particular abstract class but only 2 have the definition and 1 does not have the definition. Then it becomes the abstract class.

    So, every Interface is a abstract class but not every abstract class is interface.

  • RELEVANCY SCORE 4.19

    DB:4.19:Diff Between Interface And Abstract Class 9a



    Hi to all,

    I am woking on OOP in ABAP .Could any one can tell the difference between interface and abstract class.

    thanks in advance .

    DB:4.19:Diff Between Interface And Abstract Class 9a


    Hello Sagar,

    like Uwe told one basic difference is that you may provide some methods with an abstract class but not with an interface. The unique feature of interfaces is that you may implement several ones while abstract classes are limited to one inheritance hierarchy.

    Regards

    Klaus

  • RELEVANCY SCORE 4.18

    DB:4.18:Public Abstract Interface Filterconfig pf


    public abstract interface FilterConfig

    what is this class actually . is it abstract class or interface?

    DB:4.18:Public Abstract Interface Filterconfig pf

    interfaces are abstract because you cannot
    instantiate them.

    like you cant instantiate a abstract class.It's the other way around. You cannot instantiate them because they're abstract. Only what's fully concrete can be instantiated.

  • RELEVANCY SCORE 4.17

    DB:4.17:Simple Query ac


    Difference between Abstract class and interface with practical example

    DB:4.17:Simple Query ac

    You are right; it was a simple query. (and I don't mean "simple" as in lacking complexity.)

  • RELEVANCY SCORE 4.17

    DB:4.17:Abstract Calss Vs Interface af


    hi all,

    what are the pros and cons of abstract calss and interface?
    when to use abstract class and when to use interface???

    thanks.

    DB:4.17:Abstract Calss Vs Interface af

    Well.. this is very basic question and asked many times. Googling this question may give you good results...

  • RELEVANCY SCORE 4.17

    DB:4.17:Diff Interface And Abstract Class af


    I would like to know difference between Interface and abstract class.

    I know simple differences ... like with iterface u can achieve multiple inheritence and with abstract class can have method definition.

    It is said that with interface u achive less coupling, while its other way with abstract class.

    What exactly does this mean ?? how this is implemented programatically ??

    Cheers,
    Rana

    DB:4.17:Diff Interface And Abstract Class af

    You're not saying this is a reason not to use interfaces, are
    you?I haven't (yet) had this situation happen to me as a result of evolution of my APIs but I would think that's one thing to consider when choosing whether you should go with an abstract class or an interface for a supertype.

  • RELEVANCY SCORE 4.16

    DB:4.16:Re: Which One Is The Best And Why cs


    But implementing interface is generally more
    difficult than extending (abstract) class, because
    (abstract) class provides more things than
    interface.For a start that is wrong, it depends on the interface/abstract class.

    Secondly implementing is not relivent at all to this.

    DB:4.16:Re: Which One Is The Best And Why cs

    I think when ,
    A obja = new B();
    is used the instance variable and methods will
    not be accessible evia obja.Correct.

    B obja = new B();
    is used the instance variable and methods can
    be accessed via obja , which may involve bit more
    memory usage than the previous case .So its betterUtter BS, sorry. The object still is an instance of B.

    to go for the last case if v dont need B instance
    members not to be accessed.That doesn exist.

    and also if A is implemented by many classes
    in the ejb for bussiness logic purpose , only the
    interface is sent back as return value hiding the
    concrete class (Encapsulation)That is generalization or abstraction, not encapsulation.

    .obviously cannot have
    the concrete class with definition in the calling
    end.Huh?

  • RELEVANCY SCORE 4.16

    DB:4.16:Dificult To Understand Interface And Abstract Class 98


    - I need explain what is better to use, interface or abstract class to inherit of square/rectangle.
    Example included is appreciated. Thanks.

    DB:4.16:Dificult To Understand Interface And Abstract Class 98

    Thank you for help me.
    Do you have a classe de rectangle and square?

  • RELEVANCY SCORE 4.16

    DB:4.16:Abstract Class &Amp; Interface jp


    In which situation we use Abstract Class and in which situation we use Interface?

    DB:4.16:Abstract Class &Amp; Interface jp

    In which situation we use Abstract Class and in which
    situation we use Interface?It's a frequently asked question so search the forums.

    One answer is that from a pure typing perspective it doesn't matter because they're equal. The difference is that an abstract class can carry implementation, something an interface cannot. So pick the abstract class when you consider that beneficial.

  • RELEVANCY SCORE 4.15

    DB:4.15:Interface Vs Abstract Class sa


    when would you create an interface as opposed to an abstract class?

    DB:4.15:Interface Vs Abstract Class sa

    An interface solves the problem of multiple inheritance in Java. A class can only extend from one other class, but can implement multiple interfaces. I link to think of extending in a vertical fashion ( among a class hierarchy ), and interfaces in a horizontal fashion ( across classes that may have nothing in common ).

  • RELEVANCY SCORE 4.14

    DB:4.14:Re: Why An Interface Is Used In A Java Program pc


    These are fair comments as per as interface is concern.... we need interface to declare the methods without implementing the methods. Basically interfaces help implementing classes in a organised way.
    Now We got abstract class also, which has got more or less same features like interfaces. In abstract class also we can declare a method without implementation.
    If we use abstract class and extend that abstract class, we don't have implement all the abstract methods in that particular class,which would extend the abstract class, but if we implement an interface in a class, we have to define all the methods with their body. Now, can anyone tell me , in a generic way, when do we use interface and when do we use abstract class. I don't need the differences between abstract class and interface...that i know...thanks in advance
    take it easy
    RD
    l

    DB:4.14:Re: Why An Interface Is Used In A Java Program pc

    For Ex: 5 years down the line, .........I always wondered why it is said "down the
    line" and not up the line.
    What's so downish about the future ?People degrade as the years pass by. :P

  • RELEVANCY SCORE 4.14

    DB:4.14:Abstract Class And Interface 17



    Please tell me what is Abstract Class and Interface. Please explain with help of simple example and also tell me difference between them.

    DB:4.14:Abstract Class And Interface 17


    hi

    i will suggest u to refer some basic java book , to clear ur basic concept of OOPS , because these principal remain same for all languages that follow OOPS concept .

    and under standing these with java is easier then with ABAP .

    Abstract Class

    class which have atleast 1 method which is declared only , (no definition is given for it in this class is mentioned as Abstract Method )

    and that class is defined as Abstract class

    Interface :

    only declaration of method done here , no method will be defined here , class which will implement this interface will give definition .

    Diff. b/w Abstract Class and Interface :

    ABS Class can have method with there definition , but one method should be there with declartion only.

    Interface will have all method with out definition .

    hpoe this help u .

    reward if helpful.

  • RELEVANCY SCORE 4.13

    DB:4.13:What Is The Difference Between Abstract And Interface? zd


    Could some one explain what is the difference between abstract class and interface class.

    Lets say I'm creating class why would I choose abstract over interface?

    THanks.

    DB:4.13:What Is The Difference Between Abstract And Interface? zd

    The difference between abstract classes and interfaces is interfaces are defined methods only. In abstract class methods are derived.

  • RELEVANCY SCORE 4.13

    DB:4.13:Abstract Class Interface jx


     
     Hi,
     
      In C# is it allowed for an Abstract class to inherit from an interface and then not implement that interface. This is to force the classes that derive from the abstract class  to provide implementation for the interface(s) as well.
     
    thanks
     

    DB:4.13:Abstract Class Interface jx

     
     Thanks Hans,
     
     I have now understood the semantics (I hope I am right) . I think it would have been more appropriate if we did not need to write the extra abstract function. The class inherits
    from an interface and since its abstract anything missing should be provided by the child class.
     
    that does answer my question though, do you think I make sense here
     

  • RELEVANCY SCORE 4.12

    DB:4.12:Difference Between Abstract Class And Interface ca


    Hi everyone,

    CAn anyone explain why the following happen????

    --------------------------------------------------------------------------------
    Abstract class can have a constructor, Interface cannot.
    Abstract class can have static methods, Interface cannot.
    --------------------------------------------------------------------------------

  • RELEVANCY SCORE 4.11

    DB:4.11:Abstract Class Or Inteface 89


    Pls give me some practical example of choosing among abstract class and interface.

    DB:4.11:Abstract Class Or Inteface 89

    Search these forums using the box on the left. This question is asked about 50 times a week, there are tons of answers around