• RELEVANCY SCORE 5.33

    DB:5.33:Abstract Class 13




    Difference between abstract class and interface
    use of abstract class

    DB:5.33: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 5.21

    DB:5.21:Difference Between Inheritance And Abstract Class 9s




    difference between inheritance and abstract class

    DB:5.21: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 5.16

    DB:5.16:Difference ???? xz




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

    DB:5.16: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 5.11

    DB:5.11:Difference Between Interface And Abstract Class zm


    What is the differrence between an abstract class and an interace? and when would you use one over the other?

    DB:5.11:Difference Between Interface And Abstract Class zm

    What is the differrence between an abstract class and
    an interace? and when would you use one over the
    other?To (over-)summarise:
    An interface defines what you want to do, but doesn't tell you how to do any of it.
    An abstract class may define some of how to do it, but not necessarily all.

    RObin

  • RELEVANCY SCORE 4.99

    DB:4.99:What Are Real Roles And Abstract Roles In The Albpm 6.0? jc


    Hi All,

    what is the difference between the Real role and abstract role? Can we assign a Real role to Abstract role and vice versa?

    Edited by: user10436555 on Dec 17, 2009 2:55 AM

    DB:4.99:What Are Real Roles And Abstract Roles In The Albpm 6.0? jc

    As you are adding roles in Oracle BPM's development environment called Studio, you are adding abstract roles. Each process with Interactive activies can have one or more abstract roles. If you're using Studio for testing, abstract roles are the only thing you need to be aware of. The participants you create in Studio are assigned the roles you added in the processes. When you log into Studio's testing environment, the participant can only perform the Interactive activities in the abstract role(s) you assigned to them in Studio.

    If you're using Oracle BPM's production environment called Enterprise, real roles are mapped (matched) to the abstract roles when you deploy the processes in your project. These real roles are created inside of Enterprise's web based Process Administration application or are automatically created and mapped if you click "Smart publish" when deploying.

  • RELEVANCY SCORE 4.98

    DB:4.98: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:4.98: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 4.79

    DB:4.79: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:4.79:Difference Between Abstarct Class And Interface 7j

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

  • RELEVANCY SCORE 4.79

    DB:4.79:Difference Between Interface And Abstract Class zk


    hai

    please tell me what is the difference between interface and abstract class?

    when i want use inteface? when i want use abstrct class?

    give me the simple example for that?......

    DB:4.79:Difference Between Interface And Abstract Class zk

    This thread is moved from "JavaServer Pages (JSP) and JSTL" to here.

  • RELEVANCY SCORE 4.79

    DB:4.79:Inter Face And Abstract Class c3


    hi
    can u please tell me the difference between interface and an abstract class? In which situations they will be usefull.
    thank u
    shyam

  • RELEVANCY SCORE 4.72

    DB:4.72:Abstract Class Or Interface ? 11


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

    DB:4.72: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 4.59

    DB:4.59:Interface And Abstract Class c8


    Hi,

    Could you please let me know what is the exact difference between interface and abstract class.Which one is better to use .Could you please give me indepth answer.

    DB:4.59:Interface And Abstract Class c8

    Stop. Stop. Stop. I beg you...You're behaving like a Chinese gentleman with sand in his boots. Stop.

    Do we save the execution time by using interface.This is a compiler/byte code related question. Please post it in the proper place.

    What might be the behaviour inside the memory
    location by using interface and abstract class.Same answer.

    /Morten

  • RELEVANCY SCORE 4.58

    DB:4.58: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:4.58: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 4.51

    DB:4.51:Difference B/W Abstract Class And Interface mf


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

    Thanks in advance!

    DB:4.51: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 4.45

    DB:4.45: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:4.45: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 4.45

    DB:4.45:Re: Some Doubts z8


    1. what is the max size that a linked list can holdDepends on the heap size available to your JVM.

    2. clear difference between abstract class and
    interface.Interfaces are pure role specifications (cannot hold any implementations).
    Abstract classes usually consist of default implementations and role specifications.

    3. what is the difference of java.awt package classes
    and javax.swing package classes. why we need of swing.
    also why we need JApplet , rather than Applet ClassSwing is newer and (arguably) better and easier to use.

    DB:4.45:Re: Some Doubts z8

    i am not new....i am working with java for an year...

  • RELEVANCY SCORE 4.42

    DB:4.42: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:4.42:Please Suggest 7p

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

  • RELEVANCY SCORE 4.42

    DB:4.42: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 4.37

    DB:4.37: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:4.37: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 4.36

    DB:4.36: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:4.36: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 4.35

    DB:4.35:What Is The Main Diffrence Between Abstractclass And Interface? 87


    Hi Could anyone please explain me about main difference of abstractClass and Interface.And please give me one real Time scenario Ex:like I have requirement like Library module---Can I take the Library as an interface. I know the basic differences of interface and abstract class.

    DB:4.35:What Is The Main Diffrence Between Abstractclass And Interface? 87

    If there is a easier relation ship between the class then we can go for abstract class.Let take the example..Abstract Class:abstract class Mammals (It may be a HumanBeing or Animal){Eye(){Can set with two eyes;}abstract legs(); // we cant define the method. So it should be a abstract. Because human has two legs where as animals have four legs.}Interface:Completely different class has a same behaviours.Flyer (behavior)Bird Airplane SupermanHere three class have a same behaviour (flyer) but different implementation .

  • RELEVANCY SCORE 4.35

    DB:4.35:Difference Between Inteerface And Abstract 11


    Hi,Please Anyone can tell me What is the difference between Abstract and Interface?Where we can use interface and where we can use abstract?What is the uses of both?

    DB:4.35:Difference Between Inteerface And Abstract 11

    I agree with the all of the above, just adding one more thing:
    An interface is a pure abstract

  • RELEVANCY SCORE 4.33

    DB:4.33:Abstract And Interface fa


    Dear Sir/Madam,

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

    DB:4.33: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 4.31

    DB:4.31:Help Pls! 87


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

    Thanx!

    DB:4.31: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 4.31

    DB:4.31: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:4.31:Re: Different Between Abstract Class And Interface 77

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

  • RELEVANCY SCORE 4.28

    DB:4.28:Java Programming 33


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

    DB:4.28: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 4.26

    DB:4.26:Abstract Class And Interface 18


    what is the difference between abstract class and interface

  • RELEVANCY SCORE 4.24

    DB:4.24: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:4.24: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 4.21

    DB:4.21:Abstract Class And Interface 97


    is it any differences between abstract class and interface?

    DB:4.21: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 4.19

    DB:4.19:Good Simple Example Of Difference Between Interface And Abstract Class 83


    Hi All,

    I am new to java...

    I am confused lot about the difference between interface and abstract class....

    Can anybody tell me the difference between interface and abstract class with some good and simple exmple...

    Kindly help me...

    Thanks in advance...

    DB:4.19:Good Simple Example Of Difference Between Interface And Abstract Class 83

    phdk wrote:
    georgemc wrote:
    public class AbstractClassThatIsntAnInterface {

    public abstract void doSomething();
    public abstract void doSomethingElse();

    }Nice naming for a nonabstract class! ;-)

    @OP: read this: [http://java.sun.com/docs/books/tutorial/java/IandI/abstract.html]Er, you, um, spotted my deliberate mistake.....

  • RELEVANCY SCORE 4.19

    DB:4.19: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:4.19: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 4.15

    DB:4.15: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:4.15:Difference 7x

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

    db

  • RELEVANCY SCORE 4.15

    DB:4.15:Concept Of Abstract Class &Amp; Interface fc


    Hi friends,

    My question is what is the main difference between Abstract class Interface?

  • RELEVANCY SCORE 4.14

    DB:4.14: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:4.14: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 4.14

    DB:4.14:Simple Query ac


    Difference between Abstract class and interface with practical example

    DB:4.14:Simple Query ac

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

  • RELEVANCY SCORE 4.12

    DB:4.12: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:4.12:Abstract Class And Interfaces s7

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

  • RELEVANCY SCORE 4.12

    DB:4.12: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:4.12: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 4.12

    DB:4.12: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:4.12: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 4.11

    DB:4.11:What Is Difference Between Interface And Abstract? 3s


    Many time, I just confuse the purpose of interface and abstract.
    When should use interface or abstract in real world?
    Please give me the difference point alike point of both interface and abstract.

    Thank you.

    DB:4.11:What Is Difference Between Interface And Abstract? 3s

    Hi
    Take a look on this
    http://www.c-sharpcorner.com/UploadFile/yougerthen/104232008193919PM/1.aspx
    Reguards

    The complexity resides in the simplicity Follow me at: http://smartssolutions.blogspot.com

  • RELEVANCY SCORE 4.10

    DB:4.10: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:4.10:Interface fd

    don't encourage this nonsense

  • RELEVANCY SCORE 4.09

    DB:4.09: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:4.09: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 4.08

    DB:4.08:Re: Difference Between Abstract Class And Interface 7k


    See reply #44 and then please find something more useful to do.

    DB:4.08:Re: Difference Between Abstract Class And Interface 7k

    Passionate_Java_Lover_Vijay wrote:
    hi tigers,
    i am very new to java.
    i have a doublt iin collection.
    at wht situation what interface wil be best than other.

    where should i use List Set, Map and all.
    Advance thanks 2 guys who help me.

    Thanks
    ThinkGodJebus. Are you for real? Get a grip will you

  • RELEVANCY SCORE 4.06

    DB:4.06:Inherit Abstract Classe fc


    Can anyone show me how to make a class inherit all functionalitied from two difference abstract classes in my progam. thanks

    Jadebui.

    class a extends b ??????????
    {}

    abstract class b
    {}

    abstract class c
    {}

    DB:4.06:Inherit Abstract Classe fc

    if you want to declare both classes(b and c) as abstract you can not do multiple inheritances, try this way

    class a extends b{

    }

    abstract class b extends c{

    }

    abstract class c{

    }or you have to decide to declare one of the abstract classes as an interface

  • RELEVANCY SCORE 4.05

    DB:4.05:Difference Between Abstract Class And An Interface c3


    hi all,

    what is the difference between an ABSTRACT CLASS with full of METHOD DEFINITIONS and no implemented methods. AND an interface having the same definitions.

    In which situation we use abstract class and in which situation we use interface.

    what are the benefits.

    Can anybody explain it clearly.

    bye
    -hari

    DB:4.05:Difference Between Abstract Class And An Interface c3

    http://www.google.com/search?q=java+difference+abstract+interfaceTrying to teach a man to fish, are you?

  • RELEVANCY SCORE 4.02

    DB:4.02: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:4.02: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 4.01

    DB:4.01: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:4.01:Difference Between Abstract Class And Interfaces 9a

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

  • RELEVANCY SCORE 3.99

    DB:3.99:Abstract Class 8s


    What does it mean to declare a class as abstract?

    DB:3.99:Abstract Class 8s

    If you have at least one abstract method in your
    class, that class must be abstract.

    If you implement any interface and you dont override
    all methods of that interface, your class must be
    declared abstract.

    If you extend an abstract class and you dont override
    all abstract methods of the parent class, your class
    must be declared abstract.

    Abstract generally is used to create an specific
    behavior available to all subclasses. And each
    subclass must override that abstract method in such a
    specific behavior.

    I think thats it.There's one more situation. It's when you declare a fully concrete class to be abstract. It's useful when you want a class to act as superclass but you want to supply a default implementation to all methods. Subclasses only have to override what they want to change.

  • RELEVANCY SCORE 3.97

    DB:3.97:Difference Between Abstact Class And Interface fk


    hi

    i am new in java.

    plz tell me abstract class support which type of polymorphisam and
    interface support which type of polymorphisam
    plz explain

    bye
    siva

    DB:3.97:Difference Between Abstact Class And Interface fk

    There's only one type of polymorphism.

    Does that make it mono-polymorphism? ;)

    Indeed - do a search for the forums.

    The short answer is that both abstract classes and interfaces define required method signatures for subclasses that extend/implement them, but abstract classes can have implementation for some or all methods that are not abstract; interfaces have no implementation whatsoever for any methods.

    %

  • RELEVANCY SCORE 3.97

    DB:3.97:Java Interfaces And Abstract Classed fc


    what is the difference between interface and abstract class?

    DB:3.97:Java Interfaces And Abstract Classed fc

    I suggest you try writing some code and see.

  • RELEVANCY SCORE 3.97

    DB:3.97:Abstract Class And Interface z1


    What is most important thing about abstract class and interface.

    When to use abstract class and interface.

    DB:3.97: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 3.95

    DB:3.95:Various Data Storage Classes In Cmdb! c9



    Hi folks,

    I was going through Atrium Core Concepts planning guide to understand how various classes store data in CMDB. As per guide we have four classes namely, Regular, Categorization, Abstract and Abstract with data replication. I could not understand the difference between last two.

    It is mentioned that BMC_Memory is a categorization class. What difference would it make had it been a regular class?

    Also how would creating each of these classes impact the underlying DB structure. Can someone please explain with example?

    Regards,

    Vicky

  • RELEVANCY SCORE 3.95

    DB:3.95:Difference Between Singleton Class&Amp; Static Class kz


    What is the difference between Singleton Class Static Class

    DB:3.95:Difference Between Singleton Class&Amp; Static Class kz

    A singleton class is a class from which only one and the same instance can be obtained. This instance can have non-static variables and methods. A static class is like an utility class with only static variables and methods.

    The use of singletons is discouraged, because this almost always indicates a design flaw in the application.

  • RELEVANCY SCORE 3.94

    DB:3.94: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:3.94: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 3.94

    DB:3.94: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:3.94: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 3.93

    DB:3.93: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:3.93: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 3.89

    DB:3.89: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:3.89: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 3.86

    DB:3.86:Difference j9


    difference between abstract class and interface

    DB:3.86: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 3.86

    DB:3.86: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:3.86: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 3.86

    DB:3.86: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 3.83

    DB:3.83:Looking For Help On Abstract Method f1


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

    DB:3.83: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 3.76

    DB:3.76:J2ee Questions jj


    1. In EJB 2.0 , if Bean class has all settor and gettor method abstract
    then where it's implementation is done?

    2.What is the difference between Local and Remote Interfaces in EJB 2.0?

    3.How DSN less connection is done for EJB 2.0 ?

    DB:3.76:J2ee Questions jj

    I would confirm this answer from another PRO in J2EE,

    A Local interface will be used to fetch the skeleton code without doing a RMI call, meaning, when the EJB client is local the cleint can locate the EJB locally without making a RMI-IIOP call.

    IF you hvae more information regarding this, please update me, bthirnrayan@hotmail.com

  • RELEVANCY SCORE 3.75

    DB:3.75: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 3.75

    DB:3.75: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:3.75: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 3.75

    DB:3.75: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:3.75:Why We Use Interface? c9

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

  • RELEVANCY SCORE 3.74

    DB:3.74: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 3.74

    DB:3.74: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:3.74: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 3.74

    DB:3.74: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:3.74: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 3.73

    DB:3.73: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:3.73: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 3.72

    DB:3.72:Re: Difference Between Abstract Class And Interface. f3


    Thanks, jverd. I have got it.

    George

  • RELEVANCY SCORE 3.68

    DB:3.68:I Dont See Any Difference Between Abstract Method And Abstract Factory -Have You Find Any Difference ( Both Of Them Decouples The Client From Object Creation) 87


    I dont see any difference between Abstract method and Abstract factory - both of them decouples the client from object creation.
    If anybody knows the actual difference please explain me with differences
    Also i dont understand families of related or dependent object ..why we need to create families of related objects instead we can simply go for factory method rite ?

    Abstract method:- http://www.c-sharpcorner.com/uploadfile/kalisk/factory-method-design-pattern-using-C-Sharp/
    Abstract factory :http://lasithsameera.blogspot.com/2010/07/abstract-factory-pattern-with-c-code.html

    look at the above code...both samples are looks similar except in the Abstract factory delegates the object creation to another class..thats the only difference i can see.....Any thoughts?

    ilikemicrosoft

    DB:3.68:I Dont See Any Difference Between Abstract Method And Abstract Factory -Have You Find Any Difference ( Both Of Them Decouples The Client From Object Creation) 87

    I dont see any difference between Abstract method and Abstract factory - both of them decouples the client from object creation.
    If anybody knows the actual difference please explain me with differences
    Also i dont understand families of related or dependent object ..why we need to create families of related objects instead we can simply go for factory method rite ?

    Abstract method:- http://www.c-sharpcorner.com/uploadfile/kalisk/factory-method-design-pattern-using-C-Sharp/
    Abstract factory :http://lasithsameera.blogspot.com/2010/07/abstract-factory-pattern-with-c-code.html

    look at the above code...both samples are looks similar except in the Abstract factory delegates the object creation to another class..thats the only difference i can see.....Any thoughts?

    ilikemicrosoft

  • RELEVANCY SCORE 3.67

    DB:3.67: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:3.67: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 3.66

    DB:3.66: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:3.66: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 3.66

    DB:3.66:What Is Difference Between Abstraction And Abstract Class ? j3


    What is difference between abstraction and abstract class ?

  • RELEVANCY SCORE 3.66

    DB:3.66: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:3.66:What Is The Difference Between Abstract Class And Interface jf

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

  • RELEVANCY SCORE 3.62

    DB:3.62:Why Are We Using Abstract Class? pp


    Why are we using Abstract class? What is specify use of Abstract class?

    DB:3.62:Why Are We Using Abstract Class? pp

    Thx for the lessons....that may help with an upcoming homework assignment.

  • RELEVANCY SCORE 3.60

    DB:3.60:What's The Difference Between Abstract Class And Interface? 1z


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

    Thanks.

    Leo

    DB:3.60: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 3.59

    DB:3.59:Interfaces And Abstract Classes 8x


    Whats the difference between an interface and an abstract class.

    DB:3.59: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 3.58

    DB:3.58:Swing And Awt ax


    What is the difference between Swing and the Abstract Window Toolkit?

    DB:3.58:Swing And Awt ax

    Ok thank you. Sorry you double posting :).

  • RELEVANCY SCORE 3.57

    DB:3.57:What Is The Difference Between....... zf


    Hi, all,

    I am new to this java technology.

    I want to know, what are the differences between

    1) Interface and Abstract classes

    2) Implementing and extending a class

    Please help
    Regards
    Ash

    DB:3.57:What Is The Difference Between....... zf

    Hi,

    I am not an expert on Java, but what I know is that if a class is declared as an interface then it means it only provides a set of methods that have no implementations. So another class will implement that interface class by providing implementations to all those methods that are defined in the interface class. And a class can implement many interfaces. On the other hand if a class is declared as an abstract class then it provides methods that may or may not have implementation and another class will extend this abstract class and can override either all or some methods based on its needs. And a class can extend only one class at a time!

    I hope if my explanation is wrong, someone will correct me.

  • RELEVANCY SCORE 3.56

    DB:3.56:Difference B/W Abstract &Amp; Interface dx


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

    DB:3.56:Difference B/W Abstract &Amp; Interface dx

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

  • RELEVANCY SCORE 3.56

    DB:3.56:Assigning Object To Interface Type And Abstract Class Type. pm


    Can any one please tell me what is the difference between assigning the object to Interface type and abstractclass type instead of assigning to class type except that, if we assign an object to interface or abstractclass type, then we can access only the methods available in interface or abstract class.
    Code:
    Class cls = new Class();

    // Need Difference between the following

    Interface inf = new Class();
    AbstractClass abscls = new Class();Thankyou,
    Ram

    DB:3.56:Assigning Object To Interface Type And Abstract Class Type. pm

    Note: This thread was originally posted in the [Reflections Reference Objects|http://forums.sun.com/forum.jspa?forumID=4] forum, but moved to this forum for closer topic alignment.

  • RELEVANCY SCORE 3.56

    DB:3.56:Difference Between Discoveryproxy And Discoveryservice? mz


    Hi,
    So I'm looking at the
    WCF samples and in particular the WCF\Basic\Discovery\DiscoveryRouter and the WCF\Basic\Discovery\DiscoveryProxy.
    The DiscoveryRouter is implementing the abstract class
    DiscoveryServiceand the DiscoveryProxy is implementing the abstract class

    DiscoveryProxy. But what is the difference between those two classes - in terms of functionality? As I see it, the only difference in those two projects are that the CalculatorService in the DiscoveryProxy project contacts the Proxy using unicast, while
    the CalulatorService in the DiscoveryRouter project sends out a multicast (udp).
    Or?
    --
    Werner

    DB:3.56:Difference Between Discoveryproxy And Discoveryservice? mz

    Hi,
    Yes, you are right.
    Without using discoveryproxy, the client will send amulticast message .
    If the discoveryproxy is present in the network, then the communication takes place with the same messages, but modes change from multicast to unicast towards the discovery proxy.
    For more information, please try to refer to the following article:
    #WS-Discovery for WCF:
    http://www.codeproject.com/Articles/31285/WS-Discovery-for-WCF .
    Best Regards,
    Amy PengWe 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 3.54

    DB:3.54: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:3.54: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 3.53

    DB:3.53: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:3.53:Difference Between Pure Abstract Class And Interface? 89

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

  • RELEVANCY SCORE 3.52

    DB:3.52:Abstract/Virtual Events a3


    If you have an abstract base class which has an event that children may
    implement, and none of the base class methods connect or raise the
    event, then what's the difference between declaring that event as
    either abstract or virtual?  I can't find much of anything in the
    docs about abstract or virtual events.  

    DB:3.52:Abstract/Virtual Events a3

    IIRC (and bear with me, since I'm not near any docs), an event is effectively a field of type delegate, along with three hidden methods: raise, add and remove. Fields cannot be virtual, so one would assume that the virtual refers to the methods associated with the field.
    The base implementation of add, simply adds the delegate to the InvocationList of the delegate field, the remove reverses this operation, and the raise invokes the delegate.
    When you say MyEvent(this, EventArgs.Empty) for example, you are effectively calling the raise method. Now the interesting thing is that AFAIK you cannot override the add, remove raise methods. I can't remember why, but I'm fairly confident I'm right on this one. This sorta makes the virtual superfluous.
    If you want child classes to fire the event, the pattern is to provide a protected virtual OnEventName method which fires the method. This allows the child class to stop the event being fired if neccessary, and also to invoke it itself:
    class Parent {

    public event EventHandler MyEvent;
    protected virtual OnMyEvent() {

    if(MyEvent != null) {

    MyEvent(this, EventArgs.Empty);
    }
    }
    }
    class Child : Parent {

    public void MyMethod() {

    // Some code
    OnMyEvent(); // Fire MyEvent
    }
    // Optional, if you want to do stuff even if the event handler is not hooked up, or
    // want to modify when MyEvent is fired:
    protected void override OnMyEvent() {

    base.OnMyEvent(); // Fire MyEvent, if you want to.
    // Do some stuff.

    }

  • RELEVANCY SCORE 3.52

    DB:3.52: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:3.52: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 3.51

    DB:3.51:Abstract Class Vs Interface ak


    hi,
    i know this is a very simple question but pliz answer it with implementation details.

    What is the difference beteen ABSTRACT CLASS INTERFACE?
    Just answer me when can a programmer use ABSTRACT CLASS when can he use INTERFACE.

    i need the situation not the theory,that are available in all java books.

    keep smiling...
    Deb

    DB:3.51:Abstract Class Vs Interface ak

    Interfaces are used to allow a class to have multiple personalities. A class can implement any number of interfaces and this will allow it to be any of those types of objects. (It's almost like multiple inheratence)

    An abstract class has to be extended and you can only extend one abstract class.

    An abstract class defines a general idea of what the object is. You extend it to fill in the details.

    An interface provides a framework for expected behaviour you provide the details of that behaviour.

  • RELEVANCY SCORE 3.49

    DB:3.49:Core Java 83


    what is differernce between abstract class and interface?

    DB:3.49: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 3.49

    DB:3.49:Abstract Class And Interfaces xz


    Hi Recently

    I attended a Interview ,Interviewer asked me what is difference b/w abstract and interface.

    I cud give answer ,,he said what if abstract class has all abstract methods.in this situation is ther any difference between abstract class and interface..

    i said there will be no difference in making all methods abstract and it is similar to interface.the only difference is at one point of time u can have a class can inherit only one abstarct class whereas interface u can have more than one interface....

    I want to know is my answer is right r not..please suggest is it correct and if any other ans please do reply

    With Regards
    Mahender
    Mahender

    DB:3.49:Abstract Class And Interfaces xz

    Stepping away from purely technical differences, there are some more fundamental ones.First there is a semantic difference. A base class says that any derived classes have an is a relationship with the base. For example you could have a base class such as Stream because derived classes are streams, but you wouldn't have a base class such as Serializable because you couldn't say that a derived type is a Serializable.Secondly there is the versioning problem. With an abstract base class you can add non-abstract members in future versions without breaking any existing functionality (save for possibly name collisions) because the base class provides the implementation. With an interface you can never add members because you will break any existing implementors. http://gregbeech.com/blogs/tech

  • RELEVANCY SCORE 3.46

    DB:3.46: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:3.46: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 3.45

    DB:3.45: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:3.45: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 3.44

    DB:3.44: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:3.44: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 3.44

    DB:3.44:Interface Vs Abstract Class 97


    Hi All,
    Here I have a doubt.
    What is the difference between an bInterface/b and bAbstract class/b(Design Point of View)??.
    In which scenario which is useful.
    Can anybody kindly reply me.

    Thanks and Regards,
    Krishna Mattam
    Team Member - CDF Toolset
    Contact:044-22548575
    Email: mkrish17@ford.com

    DB:3.44:Interface Vs Abstract Class 97

    can you pls send the link to that chapter 4.6I haven't seen it online. You probably will have to buy a paper copy. It's published by Sun. It's the authorative reference on Java so it's worth having.

  • RELEVANCY SCORE 3.44

    DB:3.44:Situation That Describes Difference Between Usage Of Inetrface And Abstract Class x8


    Hi,
    Can anybody please tell me the best example or situation where we can chosse between interface and abstract class?Thanks, Smiley:)

    DB:3.44:Situation That Describes Difference Between Usage Of Inetrface And Abstract Class x8

    Hi Smiley3,
    I am marking this issue as Answered. If you have any new questions or concerns about this issue, please feel free to let me know.
    Thank you and have a nice day!Min Zhu [MSFT]
    MSDN Community Support | Feedback to us
    Get or Request Code Sample from Microsoft
    Please remember to mark the replies as answers if they help and unmark them if they provide no help.

  • RELEVANCY SCORE 3.44

    DB:3.44: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:3.44:Interface And Abstract Class ac

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

  • RELEVANCY SCORE 3.43

    DB:3.43: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:3.43: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 3.43

    DB:3.43: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:3.43: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 3.42

    DB:3.42:Regarding Abstract Interface sa


    Hello,What makes the difference between the Normal Interfaces and Abstract Interfaces. Is there any technical differences between these two interfaces.Thank you

    DB:3.42:Regarding Abstract Interface sa

    HIAbstract message interface donu2019t have a direction and arenu2019t implemented in an application system. We use them to define the process signature of an integration process.These are also called as hidden Interfaces.The Message interface is the highest level representation of XML meta data. It has two important attributes: mode (Synchronous or Asynchronous) and direction (inbound or outbound). For Business processes, Abstract interfaces are used; these have a mode, but no direction. oReferences fault message types for exception handlingoContext objects can be assigned.oWSDL representation available for exportoStarting point for Proxy generation (ABAP and Java).cheers

  • RELEVANCY SCORE 3.42

    DB:3.42: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:3.42: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:Re: What Is The Difference Between An Interface And An Abstract Class? 1a


    8000 views already wow.

    DB:3.42: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 3.41

    DB:3.41:Difference Between Abstract Class And Interface ? fz


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

    DB:3.41: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 3.40

    DB:3.40: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:3.40: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 3.39

    DB:3.39: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:3.39: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.