• RELEVANCY SCORE 5.38

    DB:5.38:C#.Net Difference Between Abstract Class And Sealed Class df




    Hi Experts, What is Difference Between Abstract Class And Sealed Class in C#? Thanks.

    Knowledge Shared Is Knowledge Gained

    DB:5.38:C#.Net Difference Between Abstract Class And Sealed Class df

    Hi Geert van Horrik, Thanks.Knowledge Shared Is Knowledge Gained

  • RELEVANCY SCORE 4.69

    DB:4.69:Abstract Class 13




    Difference between abstract class and interface
    use of abstract class

    DB:4.69: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 4.59

    DB:4.59:Abstract Class And Interface 18




    what is the difference between abstract class and interface

  • RELEVANCY SCORE 3.97

    DB:3.97:Abstract Class And Interface???? 39


    hi all, i would like to know the difference between abstract class and interface....could anybody enlighten me on this....

    DB:3.97:Abstract Class And Interface???? 39

    P.S. don't be a loser an put up multiple posts, especially on something so easy to do a search on.

  • RELEVANCY SCORE 3.97

    DB:3.97:What Is The Exact Difference Between Abstract Classes And Interface 7m


    What is the exact difference between abstract classes and interface in real scenario???

    Plz could you give a practical example???

    Thanks

    DB:3.97:What Is The Exact Difference Between Abstract Classes And Interface 7m

    At least your head doesn't make a plonk sound.Mine just makes a splutchy bursting watermelon type sound.

    To the original poster - to make things simple, if there is any doubt about which you should use, use an interface. If the situation calls for an abstract class, you will know that an interface is the wrong choice, because it will be impossible to do what you want to do with an interface.

    Drake

  • RELEVANCY SCORE 3.92

    DB:3.92:Why There Is A Different Behavior Accessing C# And Vb.Net Properties Or Method Using Vb.Net Or C# Projects? px


    Hi,
    Why there is a difference between accessing properties or method using C# project and VB.Net project.
    Intellisesnse is not showing some of the methods in C# project but able to access them when we create a object for the specific class but when we access same method in VB project, all the properties or methods able to access without defining any object.

    What is the difference between these two behaviors when trying to access same class?
    Is this the right behavior or something missed.
    Please suggest?

    //Base Class
    namespace CsharpBaseProj
    {
    public sealed class CSharpBaseClass
    {
    public string MethodFromCSharpBaseClass()
    {
    return i am from CSharpBaseClass;
    }
    }

    public abstract class Script : IScript
    {
    public CSharpBaseClass CSharpBaseClass { get; set; }

    public CSharpBaseClass TestProperty { get; set; }

    public abstract void Run(bool isSilentMode = false);
    }

    public interface IScript
    {
    /// summary
    /// Runs this instance.
    /// /summary
    void Run(bool isSilentMode = false);
    }
    }

    //C# Project

    using CsharpBaseProj;

    namespace CsharpUserScript
    {
    public class Class1 : Script
    {
    //Here Not able to access MethodFromCSharpBaseClass() // Like string str = CSharpBaseClass.MethodFromCSharpBaseClass();
    CSharpBaseClass obj = new CSharpBaseClass();

    private string s
    {
    get { return obj.MethodFromCSharpBaseClass(); }
    set { s = value; }

    }

    public override void Run(bool isSilentMode = false)
    {
    //Here able to access MethodFromCSharpBaseClass()
    string str = CSharpBaseClass.MethodFromCSharpBaseClass();

    }

    //why there is a difference between C# and VB.Net Behaviors, calling CSharpBaseClass properties or methods.
    //Is it the right behavior or missing something here.
    }
    }

    //VBProject
    Option Strict On
    #Region Imports

    Imports CsharpBaseProj

    #End Region

    Public Class Class1
    Inherits Script
    //Here able to access MethodFromCSharpBaseClass() - Please see below piece code
    Dim s As String = CSharpBaseClass.MethodFromCSharpBaseClass()

    Public Sub New()
    MyBase.New()
    End Sub

    Public Overrides Sub Run(Optional isSilentMode As Boolean = False)

    End Sub
    End Class

    Thanks in advance,

    Ravi

    DB:3.92:Why There Is A Different Behavior Accessing C# And Vb.Net Properties Or Method Using Vb.Net Or C# Projects? px

    Thanks for the reply.

    Here my point is not about displaying exception.
    VB.Net will support creating object and accessing its methods/properties outside method, why not possible in C#.net.
    Is there any specific reason, why the methods of a class should be accessed from method not from the outside of a method.
    Public
    Class
    Class1
    Inherits
    Script
    //Here able to access MethodFromCSharpBaseClass()
    Dim
    s As
    String
    =CSharpBaseClass.MethodFromCSharpBaseClass()
    End Class

    public class Class1 : Script
    {
    //Here Not able to access MethodFromCSharpBaseClass() // Like string str = CSharpBaseClass.MethodFromCSharpBaseClass(); }

    I am bit confused with the behavior.

    Please clarify

    Thanks,
    Ravi

  • RELEVANCY SCORE 3.90

    DB:3.90:What Are The Default Access Modifiers In C# ? xx


    Hi ,
    what are the default access modifiers for the following .
    1. Class
    2. Methods
    3. Variables
    4. Properties
    5. Abstract Class
    6. Abstract methods
    7. Sealed class
    8. sealed methods
    9. delegates
    10. Events
    11. Indexers

    DB:3.90:What Are The Default Access Modifiers In C# ? xx

    Hi
    Amal_ES
    Non-nested types, enumeration and delegate accessibilities (may only have internal or public accessibility)

    | Default | Permitted declared accessibilities
    ------------------------------------------------------------------
    namespace | public | none (always implicitly public)

    enum | public | none (always implicitly public)

    interface | internal | public, internal

    class | internal | public, internal

    struct | internal | public, internal

    delegate | internal | public, internal

    Nested type and member accessiblities

    | Default | Permitted declared accessibilities
    ------------------------------------------------------------------
    namespace | public | none (always implicitly public)

    enum | public | none (always implicitly public)

    interface | public | none

    class | private | All¹

    struct | private | public, internal, private²

    delegate | private | All¹

    constructor | private | All¹

    interface member | public | none (always implicitly public)

    method | private | All¹

    field | private | All¹

    user-defined operator| none | public (must be declared public)
    ¹ All === public, protected, internal, private, protected internal
    ² structs cannot inherit from structs or classes (although they can, interfaces), hence protected is not a valid modifier

    For more detaild information, please see:
    http://msdn.microsoft.com/en-us/library/ba0a1yw2.aspx
    http://msdn.microsoft.com/en-us/library/ms173121.aspx
    http://msdn.microsoft.com/en-us/library/cx03xt0t.aspx
    The above information, I just refer to
    What are the Default Access Modifiers in C#?This is a good
    summary.
    Good day!
    Kristin

    We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.

    Click
    HERE to participate the survey.

  • RELEVANCY SCORE 3.90

    DB:3.90: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 3.88

    DB:3.88:Interface, Abstract Class E Sealed Class 1d


    Bom dia a todos,
    O conceito de quando utilizar cada tipo de classe(Interface, Abstract class e Sealed Class ) pode parecer um pouco confuso as vezes!
    Algum pode me dar umas dicas e quando usar cada tipo de classe?
    Obrigado!David Ramires

    DB:3.88:Interface, Abstract Class E Sealed Class 1d

    Obrigado! pena que ninguem mais quer participar!David Ramires

  • RELEVANCY SCORE 3.83

    DB:3.83:Help Pls! 87


    Hi, can someone pls tell me what the difference between a normal class and an 'abstract class' is.

    Thanx!

    DB:3.83:Help Pls! 87

    Chris Evans just rang to call it off, apparentley he'd rather be seen with someone cool like Danny Baker and that my wife was too old for him.
    So I'll knock up a quick batch of proper nosh and meet yer all there. Hope you all like Pie and Mash Suchi, beautiful.

    Jamie

  • RELEVANCY SCORE 3.80

    DB:3.80:Subclass Vs Concrete Class fs


    Hi,

    What is the exact difference between subclass and concrete class?

    What is the need in subclassing abstract class to again abstract class?

    Thanks in Advance,
    venu.

    DB:3.80:Subclass Vs Concrete Class fs

    Hi,

    U mean to say Concrete classes are instantiatable
    and every concrete class is a subclass of some
    super class.Plz clarify me if i am wrong.That's correct. But it's also true that every class--both concrete and abstract--is a subclass of some superclass, except Object which has no superclass.

    NOTE: The following is simply provided in the interest of completeness because I'm a ballsniffing pedant. It's not that important to what you're asking about, and may just cause more confusion. Feel free to ignore it.

    Also, it's possible to make a concrete class non-instantiable by having a single private constructor and throwing an exception from it, but that's a runtime issue--the compiler will let you insstantiate the class (only from within itself if the c'tor is private).

  • RELEVANCY SCORE 3.80

    DB:3.80: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:3.80: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 3.74

    DB:3.74: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:3.74: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 3.72

    DB:3.72: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:3.72:Difference Between Pure Abstract Class And Interface? 89

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

  • RELEVANCY SCORE 3.71

    DB:3.71:Difference Between Interface And Abstract Interface 8a


    What is the difference between the following?

    interface Sample{

    }and

    abstract interface Sample{

    }Please explain it with an example.

    DB:3.71:Difference Between Interface And Abstract Interface 8a

    An all the interface's methods are public and abstract, even if you don't declare them as such. And all it's variables are public, static final, even if you don't declare them as such.

  • RELEVANCY SCORE 3.71

    DB:3.71:Best Situation That Describe Difference Between Interface And Abstract c7


    Hi, Please tell me the best example or situation where we should choose interface or abstract class?

    DB:3.71:Best Situation That Describe Difference Between Interface And Abstract c7

    Smiley,
    It is the same as about apples and computers.
    An Interface is a contract, it describes what a class should contain to implement it (and can than be used to to get those members of a class whichfulfillthe contract) but an interface contains no actual implementation.
    An Abstract Class is a class itself which can be (only) inherited used as base for another class, the members and properties of a base class can be used likewise the inheriting class.
    Because of above can an Abstract Class implement an Interface, however an Interface cannot implement an Abstract class.

    Success
    Cor

  • RELEVANCY SCORE 3.71

    DB:3.71:Difference Between Abstract Class And Interface ? fz


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

    DB:3.71: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 3.71

    DB:3.71:Abstract Classes And Interfaces kp


    I am kinda new to Java but have been studying frequently. I have a question that is probably very simple: What is the difference/advantage between an abstract Class and an Interface?

    DB:3.71:Abstract Classes And Interfaces kp

    Search the forum. Here's a topic that addresses it:
    http://forum.java.sun.com/thread.jsp?forum=31thread=273324

  • RELEVANCY SCORE 3.65

    DB:3.65:Interfaces Vs. Abstract Classes ps


    1) is there a difference between an interface (that has methods to override) and an abstract class?

    2) also what is the purpose of static members, static methods, and static classes??

    3) is there a distinction between an Abstract Data Type and User Defined Data Types?

    DB:3.65:Interfaces Vs. Abstract Classes ps

    Read Core Java Fundamentals Volume 1 by Horstmann Cornell from Sun Micro. Press release.
    Its a must to know them very well from reading it from the above book rather than relying on what you hav learnt from a discussion board. by the way, its just a personal statement, not intended to offend any fellowmates of the discussion board.

    cheers

    -tamoghna

  • RELEVANCY SCORE 3.65

    DB:3.65: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 3.63

    DB:3.63:Difference B/W Abstract &Amp; Interface dx


    Anyone tell me 4 difference b/w abstract class and interface
    plz help me

    DB:3.63:Difference B/W Abstract &Amp; Interface dx

    Asking once is enough.
    http://forum.java.sun.com/thread.jspa?threadID=734361

  • RELEVANCY SCORE 3.62

    DB:3.62:Difference Between Abstract Class And The Normal Class 7k


    Hi...........

    can anyone tell me use of abstract class instead of normal class

    The main doubt for me is...
    1.why we are defining the abstract method in a abstract class and then implementing that in to the normal class.instead of that we can straight way create and implement the method in normal class right...../

    DB:3.62:Difference Between Abstract Class And The Normal Class 7k

    Class vs. interface
    Some say you should define all classes in terms of interfaces, but I think recommendation seems a bit extreme. I use interfaces when I see that something in my design will change frequently.

    For example, the Strategy pattern lets you swap new algorithms and processes into your program without altering the objects that use them. A media player might know how to play CDs, MP3s, and wav files. Of course, you don't want to hardcode those playback algorithms into the player; that will make it difficult to add a new format like AVI. Furthermore, your code will be littered with useless case statements. And to add insult to injury, you will need to update those case statements each time you add a new algorithm. All in all, this is not a very object-oriented way to program.

    With the Strategy pattern, you can simply encapsulate the algorithm behind an object. If you do that, you can provide new media plug-ins at any time. Let's call the plug-in class MediaStrategy. That object would have one method: playStream(Stream s). So to add a new algorithm, we simply extend our algorithm class. Now, when the program encounters the new media type, it simply delegates the playing of the stream to our media strategy. Of course, you'll need some plumbing to properly instantiate the algorithm strategies you will need.

    This is an excellent place to use an interface. We've used the Strategy pattern, which clearly indicates a place in the design that will change. Thus, you should define the strategy as an interface. You should generally favor interfaces over inheritance when you want an object to have a certain type; in this case, MediaStrategy. Relying on inheritance for type identity is dangerous; it locks you into a particular inheritance hierarchy. Java doesn't allow multiple inheritance, so you can't extend something that gives you a useful implementation or more type identity.

    Interface vs. abstract class
    Choosing interfaces and abstract classes is not an either/or proposition. If you need to change your design, make it an interface. However, you may have abstract classes that provide some default behavior. Abstract classes are excellent candidates inside of application frameworks.

    Abstract classes let you define some behaviors; they force your subclasses to provide others. For example, if you have an application framework, an abstract class may provide default services such as event and message handling. Those services allow your application to plug in to your application framework. However, there is some application-specific functionality that only your application can perform. Such functionality might include startup and shutdown tasks, which are often application-dependent. So instead of trying to define that behavior itself, the abstract base class can declare abstract shutdown and startup methods. The base class knows that it needs those methods, but an abstract class lets your class admit that it doesn't know how to perform those actions; it only knows that it must initiate the actions. When it is time to start up, the abstract class can call the startup method. When the base class calls this method, Java calls the method defined by the child class.

  • RELEVANCY SCORE 3.62

    DB:3.62:Difference Between Abstract Class And Interface j3


    What is the difference between anabstract class and aninterface ?

    DB:3.62:Difference Between Abstract Class And Interface j3

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

  • RELEVANCY SCORE 3.58

    DB:3.58:Main Difference Between Virtual And Abstract Method 19


    Hi All,
    Please explain themain difference between virtual and abstract.

    Thanks in advance.

    DB:3.58:Main Difference Between Virtual And Abstract Method 19

    1 more difference is...
    Abstract methods can reside in Abstract Class only. you cannot put abstract method inconcrete class.

  • RELEVANCY SCORE 3.58

    DB:3.58: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 3.58

    DB:3.58:Java Interfaces And Abstract Classed fc


    what is the difference between interface and abstract class?

    DB:3.58:Java Interfaces And Abstract Classed fc

    I suggest you try writing some code and see.

  • RELEVANCY SCORE 3.58

    DB:3.58: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:3.58: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 3.57

    DB:3.57:Difference Between Abstraction And Abstract 98


     Could anyone give diffference between abstract and abstraction with example..

    DB:3.57:Difference Between Abstraction And Abstract 98

     senthilkr wrote:

     
    Could anyone give diffference between abstract and abstraction with example..

  • RELEVANCY SCORE 3.51

    DB:3.51: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:3.51: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 3.49

    DB:3.49: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:3.49: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 3.48

    DB:3.48:Get The Class And Methods Name Of An Abstract Sealed Class p3


    How do I get the class and methods name of an abstract sealed class? Any help will be greatly appreciated.

    DB:3.48:Get The Class And Methods Name Of An Abstract Sealed Class p3


    I disagree. It is possible to make an abstract sealed class in the c cli. Example:
    public ref class MyClass abstract sealed
    {
    ________
    __________
    };

    In most languages, this is what is typically called a static class. (For example, in C#, you can't declare abstract sealed - the compiler enforces this, but if you declare a class static, you get this in IL. Same with a VB Module. ) C/CLI
    is the only language where you can declare it like this, and you weren't saying you were using it - hence my comment.
    It's a class you can't create instances of - and will only contain static members.
    If you're working in C/CLI, an abstract sealed class will only have static method declarations, and no instance method declarations. You can still use Type.GetMethods, but you'll want to use BindingFlags.Static to retrieve them.

    You'd get this, in C/CLI, via:
    // Get the Type handle for your class
    Type^ myType = YourClass::typeid;

    // Get the public (static) methods.
    arrayMethodInfo^^methods = myType-GetMethods( static_castBindingFlags(BindingFlags::Public | BindingFlags::Static) );

    for each (MethodInfo^ mi in methods)
    Console::WriteLine(mi-Name);

    Reed Copsey, Jr. - http://reedcopsey.com
    If a post answers your question, please click Mark As Answer on that post and Mark as Helpful.

  • RELEVANCY SCORE 3.48

    DB:3.48:Interfaces And Abstract Classes 8x


    Whats the difference between an interface and an abstract class.

    DB:3.48:Interfaces And Abstract Classes 8x

    Another trait that is often overlooked is that the abstract methods and constants declared in an interface are always public; with abstract classes, you can declare them (package) and protected scope as well.

  • RELEVANCY SCORE 3.48

    DB:3.48:What Is The Difference Between Abstract And Concrete Wsdl? ap


    What is the difference between Abstract and concrete WSDL?

    DB:3.48:What Is The Difference Between Abstract And Concrete Wsdl? ap

    see : https://blogs.oracle.com/aia/entry/aia_11g_best_practices_for_dec
    for an example

    we use the abstract wsdl's so we're able to develop the process wether or not the environment (of the concrete endpoint) is up and running

  • RELEVANCY SCORE 3.45

    DB:3.45: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:3.45: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 3.42

    DB:3.42:Interface And Abstract Class Difference 18


    An interface can be used in such a way that we don't know the class of object assigned to a reference of that interface type until runtime. Can we use the abstract class in a similar way too?

    The difference between an abstract class and interface can be listed as
    1. Interface can not have implementation of any method
    2. The usage of interface and class is one other difference
    3. What other differences we have?

    DB:3.42:Interface And Abstract Class Difference 18

    941767 wrote:
    Here we have some more difference...Differences that mean nothing to an experience professional programmer.

  • RELEVANCY SCORE 3.41

    DB:3.41:Abstract Class Doubt ?? 7k


    what's the difference between the first abstract class and second abstract class .. when and where to use the first type and second type .. Please give me some info on it ...

    First Abstract Class
    public abstract class TestT where T : class
    {

    }

    Second Abstract Class

    public abstract class Test
    {

    }Regards, Gullu.

    DB:3.41:Abstract Class Doubt ?? 7k

    The second class is just a general abstract class - class that cannot be instantiated and is meant to provide common definition of a base class that multiple derived classes can share.
    More about abstract classes on MSDN.
    The first one is a generic abstract class that uses constraints to place requirements on the generic parameter (T). In your case the generic parameter can only be a type that match or inherit from specific base (you call this type 'class').
    e.g.

    public class Testable
    {

    public void Test()
    {
    //some logic here
    }

    }

    public abstract class TestT where T : Testable
    {
    public T t1;

    public void DoWork()
    {
    t1.Test(); //this will work because T must be of type Testable
    }
    }

    More about constraints on MSDN.

  • RELEVANCY SCORE 3.41

    DB:3.41:Abstract Class Or Interface ? 11


    can any one tell me the difference between an abstract class an an interface. which is more useful ?

    DB:3.41:Abstract Class Or Interface ? 11

    You could also try searching this site for your question. It has been discussed in other threads as well (I posted a simialar (how do you spell that?) question).

  • RELEVANCY SCORE 3.41

    DB:3.41:Super And This ff


    If I have an abstract class which contains a variable, say;

    protected int myInt ;

    what is the difference between calling super.myInt and this.myInt in the sub class ?

    DB:3.41:Super And This ff

    Depends. If you don't have a variable in the subclass with the same name, then it's just poor style. If you do, then they'll refer to different variables.

    Dave.

  • RELEVANCY SCORE 3.38

    DB:3.38: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:3.38: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 3.33

    DB:3.33:Java Programming 33


    what is the difference between 'abstract' class and 'interface'

    DB:3.33:Java Programming 33

    Hey, get back in line. Don't jump the queue :)Well I guess I haven't qualified myself for this
    year's hunt. Maybe I could get a free-card because I
    was always on the Most Arrogant List a few years ago.Ok. I'll be nice. You'll get a free pass.

    Kaj

  • RELEVANCY SCORE 3.33

    DB:3.33:Interface fd


    can any one tell me what is the actual difference between an abstarct class and interface.when do we use interface and when do we use abstract class in real time environment?

    DB:3.33:Interface fd

    don't encourage this nonsense

  • RELEVANCY SCORE 3.33

    DB:3.33:A C Sharp Basic Question! s9


     
    I wonder the difference between the abstract class and the interface!
    Someone help me!

    DB:3.33:A C Sharp Basic Question! s9

     xiaobin700 wrote:

     
    Thanks
    Can a method in an abstract  class be overload? And how about an interface?

  • RELEVANCY SCORE 3.33

    DB:3.33:Abstract Class 71


    Hi,
    can u tell me the exact difference between abstract class and interface.under which situations we should use this.

    DB:3.33:Abstract Class 71

    AmitChalwade123456 wrote:
    Anumanick wrote:
    Hi,
    can u tell me the exact difference between abstract class and interface.under which situations we should use this.A class implementing an interface must implement all of the methods defined in the interfacepublic abstract class ImNotImplementingThat implements Runnable {

    // public void run() {} I was going to implement this, but I can't be bothered

    }while a class extending an abstract class need not implement any of the methods defined in the abstract class. public class WhyAreYouMoaningAboutRead extends java.io.InputStream {

    // I won't compile, because I'm not implementing the abstract void method 'read'

    }Additionally, a class extending an abstract class can implement an infinite number of it's own methods.Erm

    An abstract class can contain non-abstract methods which do not have to be overridden in the subclass.Indeed

  • RELEVANCY SCORE 3.33

    DB:3.33: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:3.33: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 3.32

    DB:3.32: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:3.32: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 3.30

    DB:3.30:Re: Different Between Abstract Class And Interface 77


    any one can please tell me Difference between
    abstract class and interface. From a typing perspecitive there's no difference (you can declare variables of both). The only difference in principle is that an abstract class also can have concrete methods so it allows you ti inherit implementation along with the type. You can only inherit from one class but from as many interfaces you whish.

    Which one is best ?The short answer is that interface is best.

    DB:3.30:Re: Different Between Abstract Class And Interface 77

    Hi,please kindly help meWell, maybe if you'd post an actual question...

  • RELEVANCY SCORE 3.30

    DB:3.30:Need Help With Abstract Method ? 7p


    **************************************************
    public abstract void sleep()
    {
    ..........
    }
    **************************************************
    Could someone please tell me what is the difference of an abstract method in comparing to an instance or a class method? How should I do the invocation to an abstract method by other methods of its own class and of another class? Must I define abstract methods within abstract classes? Do I need to redefine abstract methods before using them? Thanx!

  • RELEVANCY SCORE 3.30

    DB:3.30:Difference j9


    difference between abstract class and interface

    DB:3.30: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 3.29

    DB:3.29: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:3.29: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 3.28

    DB:3.28:Difference Between Abstarct Class And Interface 7j


    HI,
    Here is a simple one for the gurus but quite important for me.

    What is the difference b/w an Interface and an abstract class?
    Why do we need each one of them?
    I would appreciate if you people can give examples of each so that I amy understand fully

    Thanks in advance...

    DB:3.28:Difference Between Abstarct Class And Interface 7j

    Sorry about the formatting, this was my first attempt at using [ code ] brackets...

  • RELEVANCY SCORE 3.27

    DB:3.27:Difference Between Abstract Interface And Normal Interface za


    Hello Friends,

    What is the Difference between abstract interface and normal interface?....

    DB:3.27:Difference Between Abstract Interface And Normal Interface za

    What is the Difference between abstract interface and
    normal interface?....The difference is that you didn't follow convention in the first case. All interfaces are implicitly abstract so you don't have to declare them as such.

  • RELEVANCY SCORE 3.27

    DB:3.27:Difference ???? xz


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

    DB:3.27: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 3.26

    DB:3.26:Interface And Abstract Class ac


    hi all,

    A method in an interface consists of access specifiers as public or abstract. what is the difference if the access specifiers for the method is public and abstract.

    regards,
    priya

    DB:3.26:Interface And Abstract Class ac

    That is correct. They must be because interface methods must be overridden when subclassed.

  • RELEVANCY SCORE 3.25

    DB:3.25:Abstract And Interface fa


    Dear Sir/Madam,

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

    DB:3.25: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 3.25

    DB:3.25:Please Suggest 7p


    public abstract MyClass
    {
    public abstract void method1();
    public abstract void method2();
    }

    public interface MyInterface
    {
    public abstract void method1();
    public abstract void method2();
    }

    What is the difference between these two ?

    DB:3.25:Please Suggest 7p

    What exactly is your question? Are you trying to understand the difference between an abstract class and interface?

  • RELEVANCY SCORE 3.25

    DB:3.25: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:3.25: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 3.25

    DB:3.25:C# Inherting An Abstract Function And Making It Virtual? dm



    Abstract methods are virtual anyway, so they can be overridden in any derived class.

    abstract class A {
    public abstract void Fire();
    }

    class B : A {
    public override void Fire() {
    }
    }

    class C : B {
    public sealed override void Fire() {
    }
    }



    However once sealed this becomes impossible:

    class D : C {
    // Nope, cannot override
    }



    The act of sealing a method (or class) simply means that it can no longer be overridden.

    DB:3.25:C# Inherting An Abstract Function And Making It Virtual? dm


    Abstract methods are virtual anyway, so they can be overridden in any derived class.

    abstract class A {
    public abstract void Fire();
    }

    class B : A {
    public override void Fire() {
    }
    }

    class C : B {
    public sealed override void Fire() {
    }
    }



    However once sealed this becomes impossible:

    class D : C {
    // Nope, cannot override
    }



    The act of sealing a method (or class) simply means that it can no longer be overridden.

  • RELEVANCY SCORE 3.25

    DB:3.25:Abstract Classes And Interfaces? dp


    Can someone tell me whats the difference between abstract classes and interfaces?

    DB:3.25:Abstract Classes And Interfaces? dp

    ...alhough an abstract class doesn't have to have any abstract methods, or any methods at all for that matter. If it has an abstract method (or doesn't implement something from an interface it claims to implement) then it must be declared abstract, but the reverse is not true--any class may be declared abstract.

  • RELEVANCY SCORE 3.23

    DB:3.23: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:3.23:Interfaces And Abstract Classes fk

    Abstarct class can never be instantiated. Same as interfaces.

    Can be
    subclassed.Same as interfaces.

  • RELEVANCY SCORE 3.21

    DB:3.21:.Net 4.0 Generic Invariance Cast Concrete Type To Base Generic Type 1x


    I am faced with the following problem:

    using System;

    using System.Collections.Generic;

    using System.Collections.ObjectModel;

    public abstract class Record { }

    public abstract class TableRecord : Record { }

    public abstract class LookupTableRecord : TableRecord { }

    public sealed class UserRecord : LookupTableRecord { }

    public abstract class DataAccessLayerTRecord : IDataAccessLayerTRecord

    where TRecord : Record, new() { }

    public abstract class TableDataAccessLayerTTableRecord : DataAccessLayerTTableRecord, ITableDataAccessLayerTTableRecord

    where TTableRecord : TableRecord, new()

    {

    #region ITableDataAccessLayerTTableRecord Members

    public void Add(TTableRecord tableRecord)

    {

    }

    public TTableRecord Get(Guid id)

    {

    return null;

    }

    public void Remove(ListTTableRecord tableRecords)

    {

    }

    #endregion

    }

    public abstract class LookupTableDataAccessLayerTLookupTableRecord : TableDataAccessLayerTLookupTableRecord, ILookupTableDataAccessLayerTLookupTableRecord

    where TLookupTableRecord : LookupTableRecord, new() { }

    public sealed class UserDataAccessLayer : LookupTableDataAccessLayerUserRecord { }

    public interface IDataAccessLayerTRecord

    where TRecord : Record { }

    public interface ITableDataAccessLayerTTableRecord : IDataAccessLayerTTableRecord

    where TTableRecord : TableRecord

    {

    void Add(TTableRecord tableRecord);

    TTableRecord Get(Guid id);

    void Remove(ListTTableRecord tableRecords);

    }

    public interface ILookupTableDataAccessLayerTLookupTableRecord : ITableDataAccessLayerTLookupTableRecord

    where TLookupTableRecord : LookupTableRecord { }

    DB:3.21:.Net 4.0 Generic Invariance Cast Concrete Type To Base Generic Type 1x

    Hi CSSS,
    I'm writing to check the issue status, does Steve's suggestion help? please feel free to let us know if you have any concern.Sincerely,
    Eric
    MSDN Subscriber Support in Forum
    If you have any feedback of our support, please contact
    msdnmg@microsoft.com.
    Please remember to mark the replies as answers if they help and unmark them if they provide no help.

    Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.

  • RELEVANCY SCORE 3.21

    DB:3.21:Concrete Class ff


    Hi

    Could someone tell me what the difference is between an abstract class, interface class and a concerte class. Cant figure it out.

    Thank you
    David

  • RELEVANCY SCORE 3.21

    DB:3.21:Difference Between Abstract Class And An Interface 3z


    Hi,
    Can any one pls define that what is exactly difference between an Abstract Class and an Interface? Also I'll appreciate if some one can tell me that what we should prefer to use and why.
    Waiting for reply,
    Pranav

    DB:3.21:Difference Between Abstract Class And An Interface 3z

    Hm, it shows some uses but it (and it's predecessor article) actually don't tell what an abstract class or an interface is (or I overlooked it :-)

    Abstract class
    An abstract class is a class which can be declared and used to derive from, but which is not possible to instantiate.

    Like Animal - there is no animal, but there are Goldfish or Cat. Thus you want no Animal objects roaming your heap but only Goldfish and Cat instances. Still it makes sense to bundle the common features in Animal, and distribute them per inheritance.

    Interface
    While a class allows to group functions and variables into a unit, an interface only allows to group functions.
    Otherwise it is the same, thus can be derived from.

    However it makes no sense to create different instances of this, because you can't seperate them, there is no variable which would hold different state information that could be used for a comparison with nonequal result.

    Java offers the multiple inheritance from interfaces only, not from classes.
    This is a simplification chosen by the language designers to keep the implementation algorithms for the tools, the VM, the memory layout of the VM and perhaps the semantics complexity simple.
    (Java was intended for remote controls and other embedded devices).

    Why is this simpler?
    If A inherits from B and A inherits from C as well.
    Plus B inherits from D, plus C inherits from D,
    then we have no longer a tree/directed acyclic graph,
    but the more general case of a directed graph.

    This makes algorithms more complicated (tree walk is easier than graph walk, where you have keep track of cycles).

    Further instantiation make more trouble.
    An instance of A would contain two instances of D, one along the path A-B-D, and one along the path A-C-D.
    Thus if B,C,D were classes with variables, B-D's variables might be different from C-D's.
    This makes access semantics and storage much more complex.

    Java simplified this problem by avoiding it by just allowing interfaces for B, C, D.
    Calling A-B-D-f() is the same as calling A-C-D-f().

    Regards,
    Marc

  • RELEVANCY SCORE 3.20

    DB:3.20: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 3.20

    DB:3.20:Difference Between Abstract Class And Interfaces 9a


    Hi,

    Any body can tell me In which scenarios we use abstract class and in which scenario we use interfaces.

    In real time applications.

    DB:3.20:Difference Between Abstract Class And Interfaces 9a

    [url http://www.javaworld.com/javaworld/jw-09-2001/jw-0921-interface.html] maximizing flexibility

  • RELEVANCY SCORE 3.20

    DB:3.20:Abstract Vs Interfaces sx


    hi i am looking for the difference between abstract classes and interfaces. i have refered a couple of books but nothing seems to satisfy me. and another thing when to use an abstract class and when to use an interface( other than multiple inheritence)

    thanks

    DB:3.20:Abstract Vs Interfaces sx

    In my opinion, Java sun programmers construct
    abstract classes in order to prevent some of the
    disadvantages of interfaces such that using only
    empty bodied method.It is a joke do not take it serious but it is really true that they construct abstract classes in order to prevent some of the disadvantages of interfaces

  • RELEVANCY SCORE 3.19

    DB:3.19: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:3.19: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 3.19

    DB:3.19:What Is The Main Difference Between Interface And Abstract Class 37


    Hi ,

    Please help on this ..

    Regards,
    vij

    DB:3.19:What Is The Main Difference Between Interface And Abstract Class 37

    All the methods declared inside interface should be abstract

    All the methods declared for an interface are abstract, by definition.

    but in case of abstract class at least one method should be abstract

    No. An abstract class is not required to have any abstract methods. It's not even a "should".

    Abstract class must be extended abstract ()
    methods generally contain only declaration part
    without definition part.
    No "generally" about it, as there are no exceptions. Abstract methods do not have a declared body, by definition.

    ~

  • RELEVANCY SCORE 3.19

    DB:3.19:Abstract Inteface 87


    What is the difference between Abstract interface and interface ?
    if there is no difference,why ServletRequest ,etc are abstract interface.
    Thanks
    Selva

    DB:3.19:Abstract Inteface 87

    SelvaBalaji wrote:
    in the eclipse have opened the interface.and where did eclipse get it from? Remember that it doesn't really matter at all and so we should probably spend our time learning more useful stuff.

  • RELEVANCY SCORE 3.18

    DB:3.18:Use Of An Abstract Keyword 37


    Hi all , I want to know about

    1.the usage of an abstract keyword.

    2.Difference between abstract and interface

    3.When to use abstract keyword.

    DB:3.18:Use Of An Abstract Keyword 37

    Hi all , I want to know about Give it a try yourself first, post it here and you get feedback.

  • RELEVANCY SCORE 3.18

    DB:3.18:Abstract Class And Interface mc


    From the design perspective what is the difference between Abstract class and Interface.
    If we are providing design, for a system. When should we use abstract class? and when should we use interface.

    DB:3.18:Abstract Class And Interface mc

    And,
    you can only "extends" one abstract class;
    but "implements" several interfaces.

  • RELEVANCY SCORE 3.18

    DB:3.18:Serialization And Generics : Problem With Xmlinclude xa


    Hello everyone.
    I've got a hierarchy of class like this:

    [Serializable]
    [xmlinclude(DiscreteDomain)]
    public abstract class Domain
    {
    }

    [Serializable]
    [xmlinclude(DiscreteDomain)]
    public abstract class DiscreteDomain : Domain
    {
    }

    [Serializable]
    public sealed class DiscreteDomainT : DiscreteDomain
    {
    }

    DB:3.18:Serialization And Generics : Problem With Xmlinclude xa

    Hello everyone.
    I've got a hierarchy of class like this:

    [Serializable]
    [xmlinclude(DiscreteDomain)]
    public abstract class Domain
    {
    }

    [Serializable]
    [xmlinclude(DiscreteDomain)]
    public abstract class DiscreteDomain : Domain
    {
    }

    [Serializable]
    public sealed class DiscreteDomainT : DiscreteDomain
    {
    }

  • RELEVANCY SCORE 3.17

    DB:3.17:Difference Between Inheritance And Abstract Class 9s


    difference between inheritance and abstract class

    DB:3.17: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 3.17

    DB:3.17:Re: What Is The Difference Between An Interface And An Abstract Class? 1a


    8000 views already wow.

    DB:3.17: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 3.17

    DB:3.17: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:3.17: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 3.15

    DB:3.15:Abstract Interface ss


    Hi All,
    What is abstract interface?What is the difference between Abstract interface and interface?
    If there is no difference why ServletRequest is abstract inteface.
    Thank You,
    Selvaraj

    DB:3.15:Abstract Interface ss

    Have a look at the JLS Chapter 9.1.1.1 abstract Interfaces
    Every interface is implicitly abstract. This modifier is obsolete and should not be used in new programs

  • RELEVANCY SCORE 3.14

    DB:3.14:Interface And Abstract Class dd


    what is the difference between interface and Abstract class?
    What are the situations we have to go for interface and Abstract class?

    DB:3.14:Interface And Abstract Class dd

    Neither an abstract class nor an interface can be instantiated (meaning you cannot create the object directly with the "new" keyword). They are both similar in that they have abstract methods. (Technically, you can create an abstract class with no abstract methods, but I would question the utility of making that class abstract in the first place).

    The two main differences are the following:

    Implementation: An abstract class can implement methods, since it is a class. An interface can never implement any methods, it only declares their signatures.Inheritance: A given class can implement an unlimited number of interfaces. A class can only extend one class. In general, I use the following rules of thumb when deciding (other developers may have differing opinions):

    Given the choice, use an interface. Since you can implement an unlimited number of interfaces, they are not as restricted, from a class hierarchy perspective. If you have several classes with the same instance (class) variables declared and several methods that all accomlplish the same thing (normally, they will even have segments of code copy-pasted between classes), then re-factor the common variables and code into an abstract class. When using interfaces, always consider delegation. Delegation is something like the following:interface IFoo {
    abstract public void bar();
    }

    public class FooDelegate {
    final public void bar() {
    // Default implementation goes here
    }
    }

    public class FooImpl implements IFoo {

    final public void bar() {
    new FooDelegate().bar();
    }
    }

    The advantage of delegation is that you can write a "helper" that contains the implementation, and then the classes that actually implement the interface can simply use the helper (e.g., delegate the implementation to another class).

    - Saish

    "My karma ran over your dogma." - Anon

  • RELEVANCY SCORE 3.13

    DB:3.13:Difference From Design Perspective 9f


    Hi,
    Can nybody tell me the difference between abstract class and interface from design point of view. This questions waz asked 2 me in an interview.

    Tx.

    Naseem Khan

    DB:3.13:Difference From Design Perspective 9f

    Well. if you really need to know the details check
    out page 118 of the Java Language Spec. The summary
    is:

    - more than one interface can be implemented by a
    class.
    - an abstract class can contain implementation.That is not the big difference, but one will see it if one contemplates on this a little.

  • RELEVANCY SCORE 3.12

    DB:3.12:Abstract Class Vs Interface And Importance Of Using xm



    Hi All,

    I want to know what is the difference between Abstract class and Interface.

    and what is the importance of using them.

    Moderator message: please search for available information/documentation.

    Edited by: Thomas Zloch on Sep 27, 2011 1:55 PM

    DB:3.12:Abstract Class Vs Interface And Importance Of Using xm


    Please refer to this thread, already this is discussed in forums

    [ABAP Objects.. Abastract Interface Class;

    Thanks

    Pavan

  • RELEVANCY SCORE 3.12

    DB:3.12:Difference Between Abstract Factory And Factory p3


    Hi,
    If anyone provide difference between abstract factory and Factory pattern with example it could be helpful
    Thanks,

    DB:3.12:Difference Between Abstract Factory And Factory p3

    Hi,
    i tried to answer differences betwen 3 factories pattern here:factory family

  • RELEVANCY SCORE 3.12

    DB:3.12:Looking For Help On Abstract Method f1


    how to use an abstract method? what is the difference between abstract and inheritance?

    DB:3.12:Looking For Help On Abstract Method f1

    An abstract method is a method that has not been implemented -- only its name, arguments, and return type have been given. This is useful from a design-by-contract viewpoint.

    You use them by overriding them, providing an implementation. (Or by not overriding them, and letting your class be abstract as a result.)

    They're so different from inheritance that it's not really meaningful to discuss the differences. It's like asking what's the difference between abstract methods and a bowl of onion soup. But they're related in that if you subclass a class with an abstract method, then your subclass has inherited the type information (i.e., the contract, the requirement to provide something that implements that method).

  • RELEVANCY SCORE 3.11

    DB:3.11:Re: Abstract Class Vs Interface Difference jc


    While this is by no means complete, the major
    differences between an interface and an abstract
    class with all abstract methods is that you don't
    have to create an implementation for the abstract
    methods in a class that extends the abstract class.Yes you do; unless the extending class is also abstract.

    You do have to implement all methods in an
    n interface. Also you can use access modifiers other
    than public in an abstract class, while interface
    methods must always be public. public or package-private?

    If you don't know why either of these things would be useful then you
    probably don't care, and could just use an interface.And seeings as people are answering here desipte the laziness; abstract classes can also have implemented methods, and member variables. Interfaces cannot.

    DB:3.11:Re: Abstract Class Vs Interface Difference jc

    While this is by no means complete, the major
    differences between an interface and an abstract
    class with all abstract methods is that you don't
    have to create an implementation for the abstract
    methods in a class that extends the abstract class.
    You do have to implement all methods in an
    n interface. No.

    The rules for what must be implemented are the same regardless of whether it's a class or an interface.

  • RELEVANCY SCORE 3.09

    DB:3.09:Static Vs Abstract Classes 17


    Just wondering if anyone knows the difference between static classes and abstract classes.

    How do static methods, static variables work?

    Is there such a thing as an abstract method?

    Thanks

    DB:3.09:Static Vs Abstract Classes 17

    Ok i think its easier to understand if u see some examples:

    abstract class X{
    protected int value;
    public abstract void setValue(int pValue);
    }
    class Y extends X{
    public void setValue(int pValue) {
    this.value=pValue;
    }//each class, which extends x has to implement this method, or the class has to be //declared abstract too
    }
    class Z extends X{
    public void setValue(int pValue) {
    this.value=2*pValue;
    }
    }

    You can use this inheritance-tree as follows:

    public class try {
    public static void main(String[] args) {
    X try=new X() //NOT possible!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    X try=new Y();
    try.setValue(10); //the value-field of try has the value 10
    try=new Z();
    try.setValue(10); //the value-field of try has the value 20
    }
    }

    The techinque i used above is called "dynamical linking" and is one of the advantages of an objectoriented language.

    The main difference of abstract and static is, that you can't instantiate an abstract class direct.

    A static class or a static method and variables has just one (and only one!!) represantation during runtime. And if you want to change the value of a static variable within a method this method has to be static too.

    Example:
    public class StaticTest {
    static int counter;
    public StaticTest() {
    counter++;
    }
    public static void print() {
    System.out.println(this.counter);
    }
    }
    public class TestClass {
    public static void main(String[] args) {
    StaticTest test;
    for (int i=0;i10;i++) {
    test=new StaticTest();
    }
    StaticTest.print(); //the output would be 10!!!!!!!!!!!!!!
    }

    }

    I hope this helps

  • RELEVANCY SCORE 3.09

    DB:3.09: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:3.09: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 3.09

    DB:3.09:Diffrence Between Abstract Class And Stack ca


    Can any one tell me the keydifferencebetween Abstract Class Stack ??

    Thanks.
    Rhythm

    DB:3.09:Diffrence Between Abstract Class And Stack ca

    They are entirely different concepts, so there isn'ta key difference I can think of. Maybe I'm missing something, care to elaborate?
    Thanks
    --mc

  • RELEVANCY SCORE 3.09

    DB:3.09:Do C++/Cli And Clr Really Support Abstract Value Types? 8x


    Hi,
    I was implementing a static class in C/CLI, something like
    public ref struct Thing sealed abstract
    {
    public:
    static void SomeFunction() {}
    };

    Then, I got a strange idea and changed the ref struct to value struct. To my surprise, Visual C 2010 SP1 compiled that just fine, and ildasm showed that Thing indeed was a sealed abstract value type:
    .class public abstract sequential ansi sealed beforefieldinit Thing extends [mscorlib]System.ValueType{ .pack 0 .size 1 .method public hidebysig static void SomeFunction() cil managed { // Code size 1 (0x1) .maxstack 0 IL_0000: ret } // end of method Thing::SomeFunction} // end of class Thing

    Visual C# 2010 SP1 decompiles this metadata to:
    public static struct Thing
    {

    public static void SomeFunction();
    }

    which is not valid C#. It causes error CS0106: The modifier 'static' is not valid for this item.
    As far as I can tell, a sealed abstract value type has no advantages over a sealed abstract reference type, so I don't think I'll be using them in practice. However, it makes me wonder: are C/CLI and the Common Language Runtime indeed intended
    to support sealed abstract value types? I couldn't find any restriction against them in ECMA-335 (Common Language Infrastructure) 6th Edition or ECMA-372 (C/CLI Language Specification) 1st Edition.

    DB:3.09:Do C++/Cli And Clr Really Support Abstract Value Types? 8x

    Thank you for the insightful reply.
    It is apparently possible to add an abstract method to Thing and make it implement an interface. The C/CLI compiler does not allow that, but ILASM and the CLR do. Then, one can cast the boxed-Thing reference (retrieved via your array hack)
    to the interface type and attempt to call the abstract method. Peverify.exe does not complain. This call does not crash the CLR; it just throws an EntryPointNotFoundException.

  • RELEVANCY SCORE 3.05

    DB:3.05:Whats The Difference Between These Types Of Classes? k8


    What's the difference between using a "private inner class", an "anonymous inner class", and a "class that implements on itself" to create a GUI?

    Also, what's the difference between regular classes, abstract classes, and interfaces?

    I ask because I'm an excellent coder, but have trouble understanding the terminology behind the code and also explaining the code.

    DB:3.05:Whats The Difference Between These Types Of Classes? k8

    You going to hand out the dukes if I bother to type a long-winded explanation? :)

  • RELEVANCY SCORE 3.03

    DB:3.03:Abstract Class And Interfaces s7


    I'm learning java on my own right now, but I still don't understand interfaces and abstract methods.What's the difference between an abstract class and interfaces? Why are interfaces important? Why can you not just create your own methods?

    Thanks

    DB:3.03:Abstract Class And Interfaces s7

    This question is asked and answered very often in this forum. Do a search.

  • RELEVANCY SCORE 3.03

    DB:3.03:Abstract Class Vs Interface sc


    can anyone pls help me in understanding difference between an interface and an abstract class which has no function with implementation

    which is better abstract cls or interface in term of speed, features..?
    Thanksbahushekh

    DB:3.03:Abstract Class Vs Interface sc

    To Mike Feng or any other moderator,
    Can you unmark
    as answer the previous post from myself please?
    Reason: It has no relevance to the original question, I was just replying to the post preceding it from RudeDog2
    which I also feel, does not really relate to the original question.
    I will leave it to Rudy to decide if He wants that post to be unmarked.

    Regards,

    John

    Click this link to see how to insert a picture into a forum post.

  • RELEVANCY SCORE 3.00

    DB:3.00:What's The Difference Between Abstract Class And Interface? 1z


    Dear all,
    Can anyone give me some hints about this topic?

    Thanks.

    Leo

    DB:3.00:What's The Difference Between Abstract Class And Interface? 1z

    Also, you can only extend one class, but can implement many interfaces. I extend a class for true is-a relationships, I use implements like mixins.

  • RELEVANCY SCORE 3.00

    DB:3.00:Normal Class Vs Abstract Class kj


    Hi I have a question, When should we use abstract class,Normal methods with virtual methods also provide similar functionality, Only
    difference is we cannot instantiate abstract class.What are differences between normal class and abstract class.

    Regards,
    Shijith

    DB:3.00:Normal Class Vs Abstract Class kj

    Hello Shijith,
    Just for the title, I would recommend you read this thread:
    http://social.msdn.microsoft.com/Forums/vstudio/en-US/71e0e521-b742-48ee-a8a8-c7fdda8a2bc4/why-do-we-need-to-use-abstract-classes-interfaces-?forum=csharpgeneral
    Why abstract is used:
    An abstract class is a special kind of class that cannot be instantiated. So the question is why we need a
    class that cannot be instantiated? An abstract class is only to be sub-classed (inherited from). In other words, it only allows other
    classes to inherit from it but cannot be instantiated. The advantage is that it enforces certain hierarchies for all the subclasses.
    In simple words, it is a kind of contract that forces all the subclasses to carry on the same hierarchies or standards.
    Then please read this:
    http://stackoverflow.com/questions/391483/what-is-the-difference-between-an-abstract-function-and-a-virtual-function

    An abstract function can have no functionality. You're basically saying, any
    child class MUST give their own version of this method, however it's too general
    to even try to implement in the parent class. A virtual function, is basically
    saying look, here's the functionality that may or may not be good enough for the
    child class. So if it is good enough, use this method, if not, then override me,
    and provide your own functionality.

    I do think their explanation is good enough for your issue.
    Regards,
    Barry Wang
    We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.

    Click
    HERE to participate the survey.

  • RELEVANCY SCORE 3.00

    DB:3.00:Why We Use Interface? c9


    I appeared one of my interviews.The Interviewee asked me a question that

    Suppose one is abstract class and one is interface.
    All the methods of abstract class are abstract.
    Then on this level what is the difference between abstract
    and interface and why we use interface. I could not answer properly.
    Please guide me the actual difference between Abstract class and Interface.
    Thanks

    DB:3.00:Why We Use Interface? c9

    google is your friend! Dear You are also my friend ;)

  • RELEVANCY SCORE 3.00

    DB:3.00:Difference Between Iserviceprovider And System.Iserviceprovider f8


    I'm a newbie to vs shell package development.

    public abstract class Package : IVsPackage, IServiceProvider, IOleCommandTarget,   

    IVsPersistSolutionOpts, IServiceContainer, System.IServiceProvider,   

    IVsUserSettings, IVsUserSettingsMigration, IVsToolWindowFactory{    ...} 

    DB:3.00:Difference Between Iserviceprovider And System.Iserviceprovider f8

    The System.IServiceProvder is an interface defined by .NET, and is analogous though not identical to the IServiceProvider interface from COM. Both of these interfaces are identified by different guids.Consequently, you will see a lot of code redefining the COM version of this interface as IOleServiceProvider.In the context of .NET constructs, System.IServiceProvider is typically used. In the context of COM interop (which the core VS IDE is based) it's the Win32/COM version that's typically used.Sincerely,Ed Dore

  • RELEVANCY SCORE 2.99

    DB:2.99:Java Language Basic Question? 8x


    1.Abstract class AbstractXMLReader implements interface XMLReader.
    2.Class SQLXMLReader extends AbstractXMLReader.
    Who can tell me what difference between the following code section?
    case 1: public class SQLXMLReader extends AbstractXMLReader implements XMLReader {}
    case 2: public class SQLXMLReader extends AbstractXMLReader {}
    Are they same?
    Many thanks
    Colin

    DB:2.99:Java Language Basic Question? 8x

    Sorry,
    i didn't try it.
    I've just try it, and Jesper is right.

    Maybe that could be useful with javaDoc (but i didn't try it).

  • RELEVANCY SCORE 2.98

    DB:2.98: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:2.98: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 2.98

    DB:2.98:Help With Interface And Abstract cs


    Hi all

    what is the difference between an interface and an abstract class??

  • RELEVANCY SCORE 2.98

    DB:2.98: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:2.98: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 2.97

    DB:2.97: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:2.97: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 2.97

    DB:2.97:What Is The Difference Between An Abstract And An Interface Class? pk


    can anyone enlighten me on this, what is the difference between an interface and an abstract class? When should i use an interface instead of a class and vice-versa? thanks!

    DB:2.97:What Is The Difference Between An Abstract And An Interface Class? pk

    public class Test extends MyClass implements MyInterface {
    public Test() {
    someAbstractMethod();
    someInterface();
    someMethodInAbstractClass();
    super.someMethodInAbstractClass();
    }
    public static void main(String[] args) {
    Test foo = new Test();
    }
    public void someAbstractMethod() {
    System.out.println("someAbstractMethod() in Test");
    }
    public void someInterface() {
    System.out.println("someInterFace() in Test");
    }
    // public void someMethodInAbstractClass() {
    // System.out.println("someMethodInAbstractClass() in Test");
    // }
    }

    abstract class MyClass {
    public void someMethodInAbstractClass() {
    System.out.println("someMethodInAbstractClass() in MyClass");
    }
    public abstract void someAbstractMethod();
    }
    interface MyInterface {
    public void someInterface();
    }Run once, uncomment code, run again, compare output

  • RELEVANCY SCORE 2.97

    DB:2.97:Simple Query ac


    Difference between Abstract class and interface with practical example

    DB:2.97:Simple Query ac

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

  • RELEVANCY SCORE 2.97

    DB:2.97: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:2.97: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 2.97

    DB:2.97:Sealed Classes, Abstract Classes And Partial Classes m1


    hello,
    What is the different between a sealed class and an abstract class?.... and also iwant to know what is the purpose of a partial class?

    DB:2.97:Sealed Classes, Abstract Classes And Partial Classes m1

    I'd also like to add that an abstract class HAS TO BE inherited. You cannot directly instantiate an abstract class.~~Bonnie DeWitt [C# MVP]
    http://geek-goddess-bonnie.blogspot.com

  • RELEVANCY SCORE 2.97

    DB:2.97: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:2.97: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.