• RELEVANCY SCORE 6.46

    DB:6.46:Abstract Class 13




    Difference between abstract class and interface
    use of abstract class

    DB:6.46: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 5.42

    DB:5.42:Difference j9




    difference between abstract class and interface

    DB:5.42: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 5.42

    DB:5.42:Difference Between Inheritance And Abstract Class 9s




    difference between inheritance and abstract class

    DB:5.42: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 5.38

    DB:5.38: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 5.38

    DB:5.38:Interface Vs Abstract Class d8


    when do we need interface and when abstract class?

    DB:5.38:Interface Vs Abstract Class d8

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

    3.Real Examples:

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

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

  • RELEVANCY SCORE 5.25

    DB:5.25:Diff. Between Interface And Abstract Class 8j


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

    DB:5.25:Diff. Between Interface And Abstract Class 8j

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

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

  • RELEVANCY SCORE 5.25

    DB:5.25:A C Sharp Basic Question! s9


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

    DB:5.25: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 5.25

    DB:5.25: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:5.25:Abstract Class And Interface mc

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

  • RELEVANCY SCORE 5.18

    DB:5.18:Core Java 83


    what is differernce between abstract class and interface?

    DB:5.18: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 5.07

    DB:5.07: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 5.07

    DB:5.07: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:5.07: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 5.07

    DB:5.07: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:5.07: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 5.07

    DB:5.07:Re: What Is The Difference Between An Interface And An Abstract Class? 1a


    8000 views already wow.

    DB:5.07: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 5.06

    DB:5.06: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:5.06: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 5.01

    DB:5.01:Abstract And An Interface ak


    Hi there,
    Can anybody please help me.I need to know the difference between the abstract and an Interface.Please explain me with a simple example.Thanks in advance.

    DB:5.01:Abstract And An Interface ak

    NJSun wrote:
    An abstract class is a class which may have the usual flavors of class members (private, protected, etc.), but has some abstract methods.Minor correction: An abstract class usually has abstract methods, but is not required to.

  • RELEVANCY SCORE 4.99

    DB:4.99:What's The Difference Between Abstract Class And Interface? 1z


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

    Thanks.

    Leo

    DB:4.99: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 4.99

    DB:4.99:Re: Difference Between Abstract Class And Interface. f3


    Thanks, jverd. I have got it.

    George

  • RELEVANCY SCORE 4.92

    DB:4.92: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:4.92: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 4.90

    DB:4.90: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:4.90:Please Suggest 7p

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

  • RELEVANCY SCORE 4.84

    DB:4.84:Abstract Class Vs Interface 9a


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

    DB:4.84:Abstract Class Vs Interface 9a

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

  • RELEVANCY SCORE 4.80

    DB:4.80:Diffrence Between A Interface And A Abstract Class? f7



    Hi OO ABAP Gurus

    Please clear below point to me.

    Diffrence between a Interface and a abstract class?

    Many thanks

    Sandeep Sharma..

    DB:4.80:Diffrence Between A Interface And A Abstract Class? f7


    Interface:

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

    Abstract Class:

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

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

  • RELEVANCY SCORE 4.80

    DB:4.80:Diference Between Abstract Class And Interface cp



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

    DB:4.80:Diference Between Abstract Class And Interface cp

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

  • RELEVANCY SCORE 4.80

    DB:4.80:Difference Between Abstract Class And Interface j3


    What is the difference between anabstract class and aninterface ?

    DB:4.80:Difference Between Abstract Class And Interface j3

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

  • RELEVANCY SCORE 4.77

    DB:4.77:Public Abstract Interface Filterconfig pf


    public abstract interface FilterConfig

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

    DB:4.77:Public Abstract Interface Filterconfig pf

    interfaces are abstract because you cannot
    instantiate them.

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

  • RELEVANCY SCORE 4.77

    DB:4.77:Difference Between Interface And Abstract Class 71


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

    DB:4.77:Difference Between Interface And Abstract Class 71

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

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

    Thanks.

  • RELEVANCY SCORE 4.74

    DB:4.74:Java Interfaces And Abstract Classed fc


    what is the difference between interface and abstract class?

    DB:4.74:Java Interfaces And Abstract Classed fc

    I suggest you try writing some code and see.

  • RELEVANCY SCORE 4.66

    DB:4.66: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 4.64

    DB:4.64:Abstact Class And Interface s9


    Hi,

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

    With
    BAbu

  • RELEVANCY SCORE 4.58

    DB:4.58: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:4.58: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 4.54

    DB:4.54: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:4.54: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 4.54

    DB:4.54: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:4.54: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 4.51

    DB:4.51:Interfaces And Abstract Classes 8x


    Whats the difference between an interface and an abstract class.

    DB:4.51: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 4.51

    DB:4.51: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:4.51:C#.Net Difference Between Abstract Class And Sealed Class df

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

  • RELEVANCY SCORE 4.45

    DB:4.45: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:4.45:Why We Use Interface? c9

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

  • RELEVANCY SCORE 4.40

    DB:4.40:Diff. Between Interface And Abstract Class 3s


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

    DB:4.40:Diff. Between Interface And Abstract Class 3s

    This question gets asked all the time. I found lots of hits by searching this forum with the words: interface abstract class difference

    I'm sure google will return even more. Searching existing posts should always be done before posting.

  • RELEVANCY SCORE 4.40

    DB:4.40:Simple Query ac


    Difference between Abstract class and interface with practical example

    DB:4.40:Simple Query ac

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

  • RELEVANCY SCORE 4.38

    DB:4.38: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:4.38: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 4.38

    DB:4.38:Who Can Tell The Difference Of The Abstract Interface Class? xf


    someone ask me that he had a abstarct interface class, such as :
    public abstract interface Book{
    }
    I was comfused, who can tell me why use it?

    DB:4.38:Who Can Tell The Difference Of The Abstract Interface Class? xf

    Cross post - http://forum.java.sun.com/thread.jspa?threadID=694601tstart=0

  • RELEVANCY SCORE 4.37

    DB:4.37: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:4.37:Interface fd

    don't encourage this nonsense

  • RELEVANCY SCORE 4.36

    DB:4.36:Concept Of Abstract Class &Amp; Interface fc


    Hi friends,

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

  • RELEVANCY SCORE 4.31

    DB:4.31:What Is The Difference B/W Abstract Class And Interface j9


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

    DB:4.31:What Is The Difference B/W Abstract Class And Interface j9

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

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

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

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

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

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

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

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

  • RELEVANCY SCORE 4.29

    DB:4.29:Java Interfaces 1a


    Java allows to put 'abstract' keyword while declaring an interface, but by definition interfaces are support to be abstract, so whether there is any specific meaning of declaring an interface abstract. I mean whats the difference between an interface and an abstract interface?

    DB:4.29:Java Interfaces 1a

    No difference whatsoever. I believe the "abstarct" keyword in interfaces is an ingheritance from previous versions

  • RELEVANCY SCORE 4.29

    DB:4.29:Regarding The Abstract And Interface km


    hai,
    I am new to java programming

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

    public abstract interface Test{}

    public interface Test{}

    public abstract class Test{}

    which kind of situations use the above interfaces and abstract classes

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

    Thanks

    DB:4.29:Regarding The Abstract And Interface km

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

    db

  • RELEVANCY SCORE 4.27

    DB:4.27:Abstract Class And Interface 18


    what is the difference between abstract class and interface

  • RELEVANCY SCORE 4.26

    DB:4.26: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:4.26: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 4.23

    DB:4.23:Difference Between Abstract Classes And Interfaces And When To Use Each a1


    Hi,
    I want to know the exact implementation differences between an abstract classes and Interfaces.
    When would we use each of them..
    Its seems that each does the same kind of functionality...but we need to just extend an abstract class in one and implement an Interface in another.

    Do let me know.

    Thanks,
    Ravi

    DB:4.23:Difference Between Abstract Classes And Interfaces And When To Use Each a1

    Hi,
    I want to know the exact implementation differences
    between an abstract classes and Interfaces.
    When would we use each of them..
    Its seems that each does the same kind of
    functionality...but we need to just extend an abstract
    class in one and implement an Interface in another.

    Do let me know.

    Thanks,
    RaviHi Ravi,
    A class must be declared abstract if one or more of its method is abstract. In case of an Interface, ALL the methods MUST be abstract. As java does not support multiple inheritence, Interface comes handy. In java, a class cannot extend from more than one class. To incorporate multiple inheritance, one can extend a class from another class and implement interface.

    public TestClass extends AbsClass implements Inter {
    }

    Thanks,
    Hope this helps,
    Karthick

  • RELEVANCY SCORE 4.23

    DB:4.23:Abstract Class And Interface z1


    What is most important thing about abstract class and interface.

    When to use abstract class and interface.

    DB:4.23: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 4.22

    DB:4.22:Difference Between Interface And Abstract Class mj


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

    Thanx

  • RELEVANCY SCORE 4.21

    DB:4.21:Abstract Class Or Interface. Which One Is Better 77


    hai everybody,

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

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

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

    DB:4.21:Abstract Class Or Interface. Which One Is Better 77

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

  • RELEVANCY SCORE 4.21

    DB:4.21:Help Pls! 87


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

    Thanx!

    DB:4.21: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 4.21

    DB:4.21:Abstract Class 71


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

    DB:4.21: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 4.20

    DB:4.20:Difference Between An Interface And An Abstract Class 9f


    Hey:

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

    DB:4.20:Difference Between An Interface And An Abstract Class 9f

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

    That's what I was looking for. Thanks.

  • RELEVANCY SCORE 4.20

    DB:4.20:Re: Difference Between Abstract Class Ans Interface 39


    Abstract classes have atleast one method abstract and interfaces have all abstract methods.

    If you are developing some application in which any entity can have more than one implementation, it is good practice to use an interface and implement the classes using interfaces.

    If some of the functionality of an entity is already known and other methods can have different implementations, then creating an abstract class is better.

    It's all a part of having a good design. Look around in the API docs and you'd find lots of abstract classes and interfaces. Try to figure out why they are so... I hope I didn't confuse you.

    Read the URL for better View

    http://java.sys-con.com/read/36250.htm

  • RELEVANCY SCORE 4.20

    DB:4.20: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:4.20: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 4.18

    DB:4.18:Difference % Abstract Class And Interface? d3


    Hi,

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

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

    Thanks for explanation.

  • RELEVANCY SCORE 4.17

    DB:4.17:Difference Between A Abstract Class With 4 Abstract Methods And A Interface With 4 Abstract Methods. 8c


    what is the difference between Difference between a Abstract class with 4 abstract methods and a Interface with 4 abstract methods.

    DB:4.17:Difference Between A Abstract Class With 4 Abstract Methods And A Interface With 4 Abstract Methods. 8c

    Your question is better rephrased as: What is the difference between an abstract class and a interfase?
    This has been discused here
    http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/67451957-f0bd-4b9b-a2c0-16f604ce8643
    Regards

  • RELEVANCY SCORE 4.15

    DB:4.15: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:4.15: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 4.15

    DB:4.15: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:4.15: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 4.12

    DB:4.12: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:4.12: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 4.08

    DB:4.08:Regarding Dynamic Binding And Abstract Class pp


    Hello Java Community,

    In dynamic biniding consept, it binds the appropriate method at run time... can any one please give me the reason how it identifes that perticular method is nearst one.....( i know that it first check sub class and then goes to super class ....... i just want how it identifys this process).....

    As per java soft new release JDK1.5 we can also write abstract class with out implimenting methods(even partially also) ... in this case if i declare all methods in abstract class were "public abstract " (like in interface methods return type) it will be similar as interface ......... and i just want in this case what is the difference between interface and abstrace class

    DB:4.08:Regarding Dynamic Binding And Abstract Class pp

    hello Sumit.Tyagi

    Thanks Q for responding...... and thanks for clearing my doubt....

    Regards
    sricharan

  • RELEVANCY SCORE 4.05

    DB:4.05:C#: What Is Difference Between Abstract Class And Interface? How To Decide To Use Which One? 18


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

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

    JaneC

    DB:4.05:C#: What Is Difference Between Abstract Class And Interface? How To Decide To Use Which One? 18

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

  • RELEVANCY SCORE 4.04

    DB:4.04:Interface Vrs Abstract Class ps


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

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

    Can people clarify why Interface and why abstract.

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

    Looking for ur inputs

    DB:4.04:Interface Vrs Abstract Class ps

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

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

  • RELEVANCY SCORE 4.03

    DB:4.03: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:4.03: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 4.02

    DB:4.02: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:4.02: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 4.02

    DB:4.02: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:4.02: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 4.00

    DB:4.00:Difference Between Abstract Interface And Normal Interface za


    Hello Friends,

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

    DB:4.00: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 4.00

    DB:4.00: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:4.00: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 3.99

    DB:3.99: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:3.99: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 3.99

    DB:3.99: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:3.99: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 3.97

    DB:3.97:Difference B/W Abstract &Amp; Interface dx


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

    DB:3.97:Difference B/W Abstract &Amp; Interface dx

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

  • RELEVANCY SCORE 3.95

    DB:3.95:Abstract? Interface? dm


    Hello! Can anybody explain me the difference between abstract classes and interface? when should i use them? Can you please give me examples?

    Thank you in advance!

    DB:3.95:Abstract? Interface? dm

    *** Abstract:

    Abstract classes are classes which are not designed to be used by the programmer. They simply enforce the declaration of certain methods on any class which subclasses them. Abstract classes can contain method declarations and instance variables.

    An example would be a very simple driving game, which offers a choice of different cars. Each car moves in the same manner, acceleration, etc. The only difference is the graphic which is used to display each car on screen. For this implementation, it would make sense to have an abstract class 'Car' which defines all the methods such as getSpeed, getDirection, setSpeed, setDirection, and so on. Its one abstract method would be getGraphic. The Car class cannot define this method since it models the 'general case' car, and so does not know what graphic is appropriate for each car.

    abstract class Car {

    /**
    * Define all the methods which are appropriate for each Car object
    */
    public int getSpeed() {
    return speed;
    }

    public void setSpeed(int i) {
    speed=i;
    }

    //etc

    //declare the abstract method
    public abstract Icon getGraphic();
    }Now you could subclass the Car class for a particular Car object:
    public class Mini extends Car {
    public Icon getGraphic() {
    return new ImageIcon("Mini.gif");
    }
    }To summarise, abstract classes are useful if you have a set of similar objects which have most of the same properties, but some method(s) are only appropriate for each individual object.

    *** Interface:

    Interfaces are useful when you need to disguise your object(s) as another type of object. By implementing the interface, the VM can recognise this.

    Interfaces differ from abstract classes in that you must write all the functions yourself. They provide no properties or methods in the base class, whereas abstract classes do.

    I hope this helps, but you would probably be best to scour the java tutorial for this topic for better examples.

  • RELEVANCY SCORE 3.93

    DB:3.93:Difference ???? xz


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

    DB:3.93: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 3.93

    DB:3.93: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:3.93: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 3.90

    DB:3.90: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:3.90:Difference Between Abstract Class And Interfaces 9a

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

  • RELEVANCY SCORE 3.87

    DB:3.87: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:3.87: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 3.86

    DB:3.86: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:3.86:Difference Between Pure Abstract Class And Interface? 89

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

  • RELEVANCY SCORE 3.84

    DB:3.84: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:3.84: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 3.80

    DB:3.80:Difference Between The Interface And Abstarct Class ss


    HI all,I have a doubt over Difference between the Interface and Abstarct classi.e interface came into play for these reasons1. pure abstartc class (this can be done using abstartc class tooo)2. multiple inheritanceif i declare a abstartc class with only abstract methods does that ressembles interface i mean them interface adn abstartc class are same ? (except inheritance case)or is any difference in case of memmory allocation etc.,Regards

    Manoj Mathe

    DB:3.80:Difference Between The Interface And Abstarct Class ss

    In interface, you can only have Public access modifier.In abstract class, all acces modifiers are allowed.For example, if you need to declare abstract methods that are internal, private, etc... and that there is no multi inheritance,you need an abstract class.There are other differences.Check this :http://www.codeproject.com/KB/cs/abstractsvsinterfaces.aspxIn terms of memory allocation, I would say it's the same, both are Reference Types, and are so managed in the same way.Hope this helps,Tom

    Thomas Aimonetti - C# - Sharplog Engineering

  • RELEVANCY SCORE 3.80

    DB:3.80:What Is The Difference Between Abstract And Interface? d8



    and pls tell me how to know tat

    wen to use static and instance

    DB:3.80:What Is The Difference Between Abstract And Interface? d8


    Abstract class can have single inheritance and Interface can have multiple inheritance.

    Class can have abstract method, which implementation not done itself and subclasses can do. it means class can partial abstract but not in case of interface.

    Kind Rgds

    Ravi Lanjewar

  • RELEVANCY SCORE 3.80

    DB:3.80: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:3.80: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 3.80

    DB:3.80: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:3.80:Difference Between Abstarct Class And Interface 7j

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

  • RELEVANCY SCORE 3.79

    DB:3.79: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:3.79: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 3.76

    DB:3.76: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:3.76: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 3.76

    DB:3.76: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:3.76: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 3.75

    DB:3.75: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:3.75: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 3.74

    DB:3.74: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:3.74: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 3.72

    DB:3.72:Differance Between Abstract Class And Interface 7s


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

    DB:3.72:Differance Between Abstract Class And Interface 7s

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

  • RELEVANCY SCORE 3.69

    DB:3.69: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:3.69: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 3.68

    DB:3.68: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:3.68:Interfaces And Abstract Classes fk

    Abstarct class can never be instantiated. Same as interfaces.

    Can be
    subclassed.Same as interfaces.

  • RELEVANCY SCORE 3.66

    DB:3.66: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:3.66: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 3.65

    DB:3.65:Abstract Class And Interface 97


    is it any differences between abstract class and interface?

    DB:3.65: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 3.65

    DB:3.65:Abstract Class Vs Interface ? 9d


    hi all,

    can anybody help me.

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

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

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

    DB:3.65:Abstract Class Vs Interface ? 9d

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

    Regards,
    Alok

  • RELEVANCY SCORE 3.65

    DB:3.65:Diff Between Abstract Class And Interface - Is This A Difference 7m


    This is quite a common topic thats discussed in any java forums . I would like to confirm if asked about the differences , can I say the following?.

    Abstract class can (or not ) have methods in it and it has no use in instantiating it since it has no meaning in instantiation.
    It has to be inherited for use .
    You need to INHERIT to use an abstract class.
    You can have a variable in Abstract class. ( a silly difference )
    Basically u use an abstract class when you want to provide a generalized form of abstraction and leave the implementation task with the inheriting subclass.

    Interface - group of related methods with empty bodies .
    You need to IMPLEMENT to use an interface.
    I dont think you can have a variable in a interface.
    When you want a few classes to use a few methods which you dont want to be included in the class ,then you go for the interface, which makes it easy to just implement and make use of the methods defined in the interface. But the problem with the interface is that, u have to implement all the methods defined in the interface , even if you dont need some of them.

    PLEASE LET ME KNOW IF THE VARIABLE THING IS A REAL DIFFERENCE. .
    I CANNOT HAVE A VARIABLE DECLARED IN MY INTERFACE RIGHT?

  • RELEVANCY SCORE 3.65

    DB:3.65: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:3.65:Re: Different Between Abstract Class And Interface 77

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

  • RELEVANCY SCORE 3.64

    DB:3.64:Difference Between Abstract Class And Interface ? fz


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

    DB:3.64: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 3.64

    DB:3.64: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:3.64: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 3.63

    DB:3.63:What Is The Different Between Abstract An Interface Class? jf


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

    DB:3.63:What Is The Different Between Abstract An Interface Class? jf

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

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

  • RELEVANCY SCORE 3.63

    DB:3.63: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 3.62

    DB:3.62:Abstract Class And Interface???? ja


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

    DB:3.62:Abstract Class And Interface???? ja

    search the forums, lot's of times answered this one has been.

  • RELEVANCY SCORE 3.62

    DB:3.62:What Is Difference Between Abstraction And Abstract Class ? j3


    What is difference between abstraction and abstract class ?

  • RELEVANCY SCORE 3.61

    DB:3.61: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:3.61: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 3.60

    DB:3.60: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:3.60:Difference 7x

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

    db