• RELEVANCY SCORE 6.35

    DB:6.35:Abstract Class 13




    Difference between abstract class and interface
    use of abstract class

    DB:6.35: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 5.25

    DB:5.25:Difference j9




    difference between abstract class and interface

    DB:5.25: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 5.25

    DB:5.25: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:5.25: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 5.19

    DB:5.19: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:5.19: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 5.18

    DB:5.18: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:5.18: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 5.18

    DB:5.18:Abstract Classes Interface ? kd


    Hello

    I wonder if anyone could help me to stright out my big questionmark regarding Abstract classes and Interfaces by answering following questions.

    1) When and why should I use Abstract classes, an real life example would be very appreciated. I have been programming for a while but I have never created an Abstract class.....

    2) Whats the difference in using Abstract classes and an interface when both of them explains whats are needed. Is an interface just an design pattern that points out which methods that are required so this particulare class should be working or correctly or?

    Thanks!

    Regards /D_S

    DB:5.18:Abstract Classes Interface ? kd

    Please search the forum or google. This has been asked, and answered about 8928911 times before.

    Kaj

  • RELEVANCY SCORE 5.13

    DB:5.13:Abstract Class Vs Interface 9d


    Hi

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

    DB:5.13:Abstract Class Vs Interface 9d

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

  • RELEVANCY SCORE 5.11

    DB:5.11:Abstract Class And Interface 97


    is it any differences between abstract class and interface?

    DB:5.11: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 5.03

    DB:5.03:Re: Does Abstract Class Really Faster Than Interfaces mm


    938864 wrote:
    Abstract class vs interface is common question and I have been hearing from time and time that abstract class are slightly faster than interfaces Please cite a reference to this.

    P.S. You will not notice any difference so who cares.

    DB:5.03:Re: Does Abstract Class Really Faster Than Interfaces mm

    In what respect have I not just answered exactly that question?

  • RELEVANCY SCORE 4.99

    DB:4.99:What Is The Difference Between Abstract Class And Interface jf


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

    Thanks and Regards
    Kranthi

    DB:4.99:What Is The Difference Between Abstract Class And Interface jf

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

  • RELEVANCY SCORE 4.98

    DB:4.98:Interface &Amp; Abstract Class d3


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

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

    DB:4.98:Interface &Amp; Abstract Class d3

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

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

  • RELEVANCY SCORE 4.98

    DB:4.98: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:4.98:Difference Between Interface And Abstract Class zk

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

  • RELEVANCY SCORE 4.96

    DB:4.96: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:4.96: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 4.94

    DB:4.94:Re: Difference Between Abstract Class And Interface. f3


    Thanks, jverd. I have got it.

    George

  • RELEVANCY SCORE 4.93

    DB:4.93:Abstract Class z3



    Hi to all,

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

    Thanks Regards

    Priya

    DB:4.93:Abstract Class z3


    Thanks Matthew .

    Thanks Regards

    Priya

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

  • RELEVANCY SCORE 4.92

    DB:4.92:Difference Between Abstract Interface And Normal Interface za


    Hello Friends,

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

    DB:4.92: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 4.86

    DB:4.86: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:4.86: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 4.74

    DB:4.74: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:4.74: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 4.72

    DB:4.72: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:4.72: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 4.68

    DB:4.68: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:4.68: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 4.64

    DB:4.64: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:4.64: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 4.64

    DB:4.64: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:4.64:Difference 7x

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

    db

  • RELEVANCY SCORE 4.63

    DB:4.63:What Is The Main Difference B/W Interface And Abstract Class 83


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

    DB:4.63:What Is The Main Difference B/W Interface And Abstract Class 83

    abstract class can be have methods with body

    interface cannot

    interface is 100% abstract class

  • RELEVANCY SCORE 4.63

    DB:4.63:Abstract Class Vs Interface ? 9d


    hi all,

    can anybody help me.

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

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

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

    DB:4.63:Abstract Class Vs Interface ? 9d

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

    Regards,
    Alok

  • RELEVANCY SCORE 4.63

    DB:4.63: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:4.63: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 4.61

    DB:4.61:Interfaces And Abstract Classes 8x


    Whats the difference between an interface and an abstract class.

    DB:4.61: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 4.61

    DB:4.61: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:4.61: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 4.58

    DB:4.58: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:4.58: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 4.53

    DB:4.53:What Is The Main Difference Between Interface And Abstract Class 37


    Hi ,

    Please help on this ..

    Regards,
    vij

    DB:4.53:What Is The Main Difference Between Interface And Abstract Class 37

    All the methods declared inside interface should be abstract

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

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

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

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

    ~

  • RELEVANCY SCORE 4.51

    DB:4.51: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 4.48

    DB:4.48:Interfaces And Abstract Classes 73


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

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

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

    DB:4.48:Interfaces And Abstract Classes 73

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

  • RELEVANCY SCORE 4.48

    DB:4.48:What Is The Difference Between Abstract And Interface? zd


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

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

    THanks.

    DB:4.48:What Is The Difference Between Abstract And Interface? zd

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

  • RELEVANCY SCORE 4.48

    DB:4.48: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:4.48: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 4.46

    DB:4.46:Re: What Is The Difference Between An Interface And An Abstract Class? 1a


    8000 views already wow.

    DB:4.46:Re: What Is The Difference Between An Interface And An Abstract Class? 1a

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

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

  • RELEVANCY SCORE 4.36

    DB:4.36: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:4.36:Re: Different Between Abstract Class And Interface 77

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

  • RELEVANCY SCORE 4.36

    DB:4.36:Difference B/W Abstract &Amp; Interface dx


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

    DB:4.36:Difference B/W Abstract &Amp; Interface dx

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

  • RELEVANCY SCORE 4.34

    DB:4.34: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:4.34: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 4.34

    DB:4.34:Abstract Class And Interface 3j


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

    With Regards,
    Stalin.G

    DB:4.34:Abstract Class And Interface 3j

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

  • RELEVANCY SCORE 4.34

    DB:4.34:What Is The Difference Between Abstract Class And Interface af


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

    DB:4.34:What Is The Difference Between Abstract Class And Interface af

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

  • RELEVANCY SCORE 4.34

    DB:4.34: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:4.34: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 4.34

    DB:4.34:Difference From Design Perspective 9f


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

    Tx.

    Naseem Khan

    DB:4.34:Difference From Design Perspective 9f

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

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

  • RELEVANCY SCORE 4.33

    DB:4.33:Re: Interface m8


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

    DB:4.33:Re: Interface m8

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

    :o)LOL!

    This kills me - just bcuz.

    %

  • RELEVANCY SCORE 4.33

    DB:4.33:Difference Between Pure Abstract Class And Interface? 89


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

    Thanks,

    DB:4.33:Difference Between Pure Abstract Class And Interface? 89

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

  • RELEVANCY SCORE 4.33

    DB:4.33:Java Programming 33


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

    DB:4.33:Java Programming 33

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

    Kaj

  • RELEVANCY SCORE 4.33

    DB:4.33: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 4.30

    DB:4.30: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:4.30: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 4.26

    DB:4.26:Abstract Class Or Inteface 89


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

    DB:4.26:Abstract Class Or Inteface 89

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

  • RELEVANCY SCORE 4.26

    DB:4.26: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 4.25

    DB:4.25:Mdb Abstract Base Class And Ejb3 Annotations 1k



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

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

    }
    }

    DB:4.25:Mdb Abstract Base Class And Ejb3 Annotations 1k


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

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

    }
    }

  • RELEVANCY SCORE 4.25

    DB:4.25:Interface Vs Abstract Class sz


    Let say that an abstract class has all abstract functions and someone use it instead of interface.
    What are the disadvantage and advantages?
    I know one that he cannot do multiple inheritance, hence he cannot extends abstract class and use any other parent Class. However, I wish to know more disadvantage/advantages.

    Looking forward for your input.

    --
    PS: I know interface cannot have code and abstract class could have code (non-abstract) methods.

    .

    DB:4.25:Interface Vs Abstract Class sz

    HowToDoIt wrote:
    Let say that an abstract class has all abstract functions and someone use it instead of interface.
    What are the disadvantage and advantages?
    I know one that he cannot do multiple inheritance, hence he cannot extends abstract class and use any other parent Class. However, I wish to know more disadvantage/advantages.

    Looking forward for your input.

    --
    PS: I know interface cannot have code and abstract class could have code (non-abstract) methods.

    .An Interface expresses a contract.
    A class implementing an interface is saying "I will supply implementations of all methods described in the interface, i.e. methods with those particular signatures"

    A class can of course implement multiple interfaces, i.e. it is capable of fulfilling multiple contracts.

    An Abstract class is used to provide a 'base' implementation of some specific functionality (whether it is described in an Interface or not).

    I cannot think of a useful purpose for an abstract class that contains only abstract methods (perhaps it inherits some behavior from its base class)

    Usually some methods in an abstract class WILL be implemented, either because they are unlikely to change in child classes, or they provide a guide/example of implementation, or the implemented methods may be defined in terms of some of the abstract methods, this allows classes which extend the abstract class to 'mix in' their behavior with that of the base abstract class.

    So Interface and Abstract Class have two distinct and separate purposes.

    I hope that is clear?

    Just to help with the details, you can put more than just method signatures in an interface, your could for example have in your interface

    public interface Face1
    {
    public static final int x = 3;
    }which you would access as:

    int fred = Face1.x;And you can place a public static class inside of your interface, the methods of which you would access in a similar way, but you should avoid this unless you really know what you are doing.

  • RELEVANCY SCORE 4.23

    DB:4.23:Use Of Abstract And Interface? k3


    when i use Abstract class or Interface.Which one is better?

    DB:4.23:Use Of Abstract And Interface? k3

    Depends on what you want to do. An interface is more general (in that it doesn't define any actual behavior) and allows you to mimic multiple inheritance (a class can implement any number of interfaces whereas it can only extend one class (abstract or otherwise)). Abstract is good if you have a common base of functionality that all of the implementers will be using.

    It's also fairly common to use both (i.e. the interface TableModel and the abstract class AbstractTableModel), so that someone who wants to completely write their own implementation is free to, while someone who wants to just extend or change the standard functionality could do that as well.

  • RELEVANCY SCORE 4.23

    DB:4.23: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:4.23: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 4.22

    DB:4.22: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:4.22:C#.Net Difference Between Abstract Class And Sealed Class df

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

  • RELEVANCY SCORE 4.22

    DB:4.22:Difference Between Abstract Class And Interface ? fz


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

    DB:4.22:Difference Between Abstract Class And Interface ? fz

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

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

  • RELEVANCY SCORE 4.22

    DB:4.22:Confusion Between Abstract And Interface a8


    Hi all,
    i'm new to java, can somebody help to explain on abstract and interface method. As i know that abstract or interface does not provide implementation in the superclass and interface class respectively. All the implementation are done in subclass.. why not we use the inheritances and abstract method to solve the problem instead of using the interface... i can't see the difference between the abstract and interface.. can somebody provide me a good example to understand the interface well..

    p/s: pls correct me if i wrong... ;)
    thanks

    DB:4.22:Confusion Between Abstract And Interface a8


    public class abstract Mainclass{
    abstract double area();
    abstract double meter();
    }

    public class Subclass1 extends Mainclass{
    double area(){
    return 5+1;
    }
    }

    public class Subclass2 extends Mainclass{
    double area(){
    return 8+10;
    }
    }Let's say you have
    public class abstract AreaClass {
    abstract double area();
    abstract double meter();
    }And then when you are working on your second iteration and you want to use Dimension class for this purpose for your new code but you want to leave the old code alone. If you have made AreaClass an abstract class, this is impossible.
    public class AreaDimension extends AreaClass, Dimension {
    }will not compile. However if you had defined AreaClass as and interface you can do this:
    public class AreaDimension extends Dimension implements AreaClass {
    double area() {
    return height * width;
    }
    }Then you can pass this to any method that accepts an AreaClass as a parameter and you can also pass it to any method that takes a Dimension.

  • RELEVANCY SCORE 4.22

    DB:4.22:Difference Between Abstract Class And Interface ca


    Hi everyone,

    CAn anyone explain why the following happen????

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

  • RELEVANCY SCORE 4.21

    DB:4.21: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:4.21: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 4.20

    DB:4.20:Difference Between Abstract Classes Vs Interface 77


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

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

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

    Please Reply me
    Thanks Regards
    Venkatesh

  • RELEVANCY SCORE 4.16

    DB:4.16:Interface And Abstract Class dc


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

    DB:4.16:Interface And Abstract Class dc

    Simpler reason: interfaces have no implementation. Period.

  • RELEVANCY SCORE 4.14

    DB:4.14:A C Sharp Basic Question! s9


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

    DB:4.14: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 4.14

    DB:4.14:Re: Difference Between Abstract Class And Interface 7k


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

    DB:4.14: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 4.12

    DB:4.12:Abstract And Interface? cm


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

    DB:4.12:Abstract And Interface? cm

    Oh please, do some research of your own.

  • RELEVANCY SCORE 4.11

    DB:4.11: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:4.11: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:When To Use Abstract Class And Interface? jp


    hi,

    When to use Abstract class and Interface?

    DB:4.11:When To Use Abstract Class And Interface? jp

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

  • RELEVANCY SCORE 4.11

    DB:4.11: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:4.11: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 4.08

    DB:4.08:Abstract Class And Interface 17



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

    DB:4.08:Abstract Class And Interface 17


    hi

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

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

    Abstract Class

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

    and that class is defined as Abstract class

    Interface :

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

    Diff. b/w Abstract Class and Interface :

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

    Interface will have all method with out definition .

    hpoe this help u .

    reward if helpful.

  • RELEVANCY SCORE 4.07

    DB:4.07:Interface Vs Abstract Class d8


    when do we need interface and when abstract class?

    DB:4.07:Interface Vs Abstract Class d8

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

    3.Real Examples:

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

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

  • RELEVANCY SCORE 4.04

    DB:4.04: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:4.04:Abstract Class Vs Interface 9a

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

  • RELEVANCY SCORE 4.04

    DB:4.04:Use Of An Abstract Keyword 37


    Hi all , I want to know about

    1.the usage of an abstract keyword.

    2.Difference between abstract and interface

    3.When to use abstract keyword.

    DB:4.04:Use Of An Abstract Keyword 37

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

  • RELEVANCY SCORE 4.03

    DB:4.03: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:4.03: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 4.02

    DB:4.02: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:4.02: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 4.02

    DB:4.02:Difference ???? xz


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

    DB:4.02:Difference ???? xz

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

  • RELEVANCY SCORE 4.00

    DB:4.00: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:4.00: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 4.00

    DB:4.00: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:4.00:Difference Between Abstarct Class And Interface 7j

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

  • RELEVANCY SCORE 3.98

    DB:3.98:Who Can Tell The Difference Of The Abstract Interface Class? 79


    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:3.98:Who Can Tell The Difference Of The Abstract Interface Class? 79

    http://java.sun.com/docs/books/tutorial/java/interpack/interfaceDef.html

    Scroll down to the bottom.

    Drake

  • RELEVANCY SCORE 3.98

    DB:3.98:Difference % Abstract Class And Interface? d3


    Hi,

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

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

    Thanks for explanation.

  • RELEVANCY SCORE 3.98

    DB:3.98: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:3.98: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:Static Methods In Interfaces 3z


    Java cognoscenti,

    Anyone know why I can't declare a method as static in an interface, but I can in an abstract class. Surely, semantically it's the same - defering the implementation of a static method, not an abstract class and an interface. By the way, I'm using JDK 1.2.2 if that makes a difference

  • RELEVANCY SCORE 3.95

    DB:3.95: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:3.95:Java Interfaces 1a

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

  • RELEVANCY SCORE 3.95

    DB:3.95: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:3.95:Differance Between Abstract Class And Interface 7s

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

  • RELEVANCY SCORE 3.95

    DB:3.95: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:3.95: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 3.95

    DB:3.95:About Interface In Java 7z


    what is basic idea behind the interface and abstract class

    DB:3.95:About Interface In Java 7z

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

  • RELEVANCY SCORE 3.94

    DB:3.94: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:3.94:Interfaces And Abstract Classes fk

    Abstarct class can never be instantiated. Same as interfaces.

    Can be
    subclassed.Same as interfaces.

  • RELEVANCY SCORE 3.93

    DB:3.93:What Is An Interface &Amp; Abstract Class ? zm


    hi ,
    i am new to java,
    pls give the answer for this question,

    what is an interface abstract class ?
    why we go for interfaces and abstract classes?

  • RELEVANCY SCORE 3.92

    DB:3.92:What Is The Exact Difference Between Abstract Classes And Interface 7m


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

    Plz could you give a practical example???

    Thanks

    DB:3.92:What Is The Exact Difference Between Abstract Classes And Interface 7m

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

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

    Drake

  • RELEVANCY SCORE 3.88

    DB:3.88:Core Java 83


    what is differernce between abstract class and interface?

    DB:3.88: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 3.87

    DB:3.87:Abstract Class And Interface 7x


    Hi,
    This is ramana, I got a doubt
    1. I have one interface
    interface Intabs {
    abstract void method1();
    abstract void method2();
    abstract void method();

    }
    2. Iam trying to convert that interface into abstract class like below
    interface Intabs {
    abstract void method1();
    abstract void method2();
    abstract void method();

    }
    3. Again iam trying to extend that abstract class into class like below
    interface Intabs {
    abstract void method1();
    abstract void method2();
    abstract void method();

    }

    Iam getting errors

    Can i do it in multiple steps: Interface------abstract class----- class

    DB:3.87:Abstract Class And Interface 7x

    Cannot reduce the visibility of the inherited method
    from IntabsDerabst1.java
    Right. As mentioned, you can't assign weaker access priveleges to inherited methods. If you define a method as "public void foo() {}", the "foo()" method must have at least public access in all subtypes. In your example, your interface methods are public, but you're trying to give them "package-private" (default) access in the abstract and concrete implementation classes.

    ~

  • RELEVANCY SCORE 3.86

    DB:3.86:What's The Difference Between Abstract Class And Interface? 1z


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

    Thanks.

    Leo

    DB:3.86: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 3.84

    DB:3.84:Abstract Class Or Interface ? 11


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

    DB:3.84:Abstract Class Or Interface ? 11

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

  • RELEVANCY SCORE 3.84

    DB:3.84:Abstract Inteface 87


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

    DB:3.84:Abstract Inteface 87

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

  • RELEVANCY SCORE 3.84

    DB:3.84:Abstract Class And Interface z1


    What is most important thing about abstract class and interface.

    When to use abstract class and interface.

    DB:3.84: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 3.83

    DB:3.83: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:3.83: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 3.83

    DB:3.83:Make Abstract Class With Interface. 39


    I want to make an abstract class with methods that need interfacing, but I don't want to make an entire other class for the abstract class to implement. Is there any way to make an abstract class and interface combined into one class with no implementations on that class?

    DB:3.83:Make Abstract Class With Interface. 39

    if you want a class with no implementations that what you need is an Interface

  • RELEVANCY SCORE 3.82

    DB:3.82:Interface fd


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

    DB:3.82:Interface fd

    don't encourage this nonsense

  • RELEVANCY SCORE 3.81

    DB:3.81: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:3.81:Interface And Abstract Class ac

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

  • RELEVANCY SCORE 3.80

    DB:3.80: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 3.79

    DB:3.79:Interface And Abstract Class ad


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

    DB:3.79:Interface And Abstract Class ad

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

  • RELEVANCY SCORE 3.77

    DB:3.77: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:3.77: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 3.76

    DB:3.76: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:3.76:Abstract Class And Interface???? ja

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

  • RELEVANCY SCORE 3.75

    DB:3.75:Abstract Class Vs Interface sc


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

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

    DB:3.75:Abstract Class Vs Interface sc

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

    Regards,

    John

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

  • RELEVANCY SCORE 3.74

    DB:3.74:Interface And Abstract Class dd


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

    DB:3.74:Interface And Abstract Class dd

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

    The two main differences are the following:

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

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

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

    public class FooImpl implements IFoo {

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

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

    - Saish

    "My karma ran over your dogma." - Anon

  • RELEVANCY SCORE 3.73

    DB:3.73: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:3.73: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]