static « interface « Java Class Q&A

Java Class Q&A
1.abstract class
2.Base class
3.class hierarchy
4.class name
5.class version
14.equal method
15.extend Class
19.inner class
21.main class
26.object reference
28.parent class
31.Private Field
35.Static Class
39.Wrapper Class
Java Class Q&A » interface » static 

1. Why would a static inner interface be used in Java?

I have just found a static inner interface in our code-base.

class Foo {
    public static interface Bar {
        /* snip */

2. Why can't I declare static methods in an interface?

The topic says the most of it - what is the reason for the fact that static methods can't be declared in an interface?

public interface ITest {
    public ...

3. Alternatives to static methods in Java

I'm making a mini ORM for a Java program I'm writing... there is a class for each table in my db, all inheriting from ModelBase. ModelBase is abstract & provides a bunch ...

4. Why can't I define a static method in a Java interface?

Here's the example:

public interface IXMLizable<T>
  static T newInstanceFromXML(Element e);
  Element toXMLElement();
Of course this won't work. But why not? One of the possible issues would be, what happens when you ...

5. Java - Why all fields in an interface are implicitly static and final?

I am just trying to understand why all fields defined in an Interface are implicitly static and final. The idea of keeping fields static makes sense to me as you can't ...

6. Java interfaces... Dynamic or static memory?

Where do java interfaces reside in memory? Do they reside in the heap or the stack, or maybe global memory? I am thinking the are in the stack since they are ...

7. Interfaces, static classes problem

I am currently moving all my Game code to another package so that I can simply reuse it when I create another similar game. I am having some problems with this though.

public ...

8. Why are interface variables static and final by default?

Why are interface variables static and final by default in Java?

9. interface variables are final and static by default and methods are public and abstract

The question is why it's been decided to have variable as final and static and methods as public and abstract by default. Is there any particular reason for making them implicit,variable as ...

10. Is there a way to make sure classes implementing an Interface implement static methods?

First of all, I read erickson's useful reply to "Why can’t I define a static method in a Java interface?". This question is not about the "why" but about the ...

11. Java: implementation of simple commands

I have created a pkg for my regular simple commands. They are non-static, to be more extensible, but somewhat more time-consuming to use because of creating object to use one. My ...

12. How to find a static String in a Interface

I have the folowing interface;

public static interface Attributes
        public final static String InterestDeterminationDate = "InterestDeterminationDate";
        public final ...

13. why interface doesn't support static method?

Possible Duplicate:
Why can’t I declare static methods in an interface?
Inside the interface body we aren't able to declare or define any static method. What ...

14. Static member class cannot implement an interface

Can anyone explain why a static member class cannot implement an interface, unless the interface is a marker?

15. Should I nest static or not static interfaces within a parent interface

To create conditionally validated groups with jsr 303 validation, an interface class is passed to the annotation like this:

@NotEmpty (groups={UpdateValue.class})
I have quite a few different interface types that I want to ...

16. need of Static variables and their overhead on jvm

As per the concept about static members, they are created/loaded into the memory when there is first call made to its class. And they are common among all instances of that ...

17. Advice needed: static methods in JAVA interface

I have a class that is handling printing the various messages into the console, lets call this class This class is public and abstract and all its methods are public ...

18. Initializing static field in interface with exception handling

Well, in fact I would like to do the following in an interface:

public interface ObjectMethods
    static Method getModulus = RSAPublicKey.class.getMethod("setModulus", byte[].class, short.class, short.class);
This of course leads to a ...

19. Techniques to expose multiple Interfaces (via static creation methods)

I am currently working on a project where I am attempting to hide as much detail about a hierarchy I have created as possible. I want to do this to minimize ...

20. Non-static variable referenced in static context error with interface

I am fairly new to Java (especially interfaces) and I have this simple comparison interface set up and am wishing to create an integer implementation for it. When I compile, the ...

21. Can a top-level class or interface have the "static" modifier?

I have a doubt: Can a top-level class or interface be declared as static? Example:

// File
static Class A

22. Iterating through classes with static functions

I have Model class like this

class ModelName {
    public static void createTable(SQLiteDatabase db){
        // code to create Table in DB

24. Nested interfaces implicitly static?

My code below appears to demonstrate that nested interfaces are implicitly static. First, note that the compiler treats the nested interface as a static context; and second, the nested interface can be implemented without an instance of the enclosing class (even outside of that class). Is this documented anywhere? The Java Language Specifications state that interfaces can be a members of ...

25. Interfaces and Static and design advice request

Hi there. Why can one not do the following? public interface AllFruit{ public static void makeFruit(); } This is not a homework question - here is the whole story... For the app, there is Module1 and Module2. Now M1 exists on it's own but M2 must have M1. That is, M2 will never exist on it's own. In M2 there are ...

26. static interfaces

27. Interfaces and Static Methods

I have an app that consist of a core application and an application instance. The db connection, queries, etc. All reside in the application instance so the system can work with any db they want. Recently, I tried to connect to 'new' MS SQL Server 2005 and found I had to tweak my DAO class a little to work with it. ...

28. Why can't interfaces define a static method

The simple answer to all such questions is "because the Java Language Specification says so". In many such questions, it would be possible to imagine how the feature under discussion might have been allowed. The language designers had to make judgements about what features would be useful, understandable, easy to implement in compilers/JVMs, and encourage good programming. Static methods in interfaces ...

29. (Design Perspective)Static method in interface

In an interface you cannot provide an implementation of a method and static methods are not polymorphic (they cannot be overridden), so it would make no sense to be able to have a static method in an interface: there would be no way to provide an implementation for the method. [ July 12, 2007: Message edited by: Jesper Young ]

30. static Methods @ Interface

Hi Jeanne, Yes i do agree with your comments. Because the static methods will live in the class objects not in the instance object.... However can't we implement polymorphisms at Class level ???... class ParentClass{ public static void sleep(){System.out.println("Calling parent ");} } class ChildClass extends ParentClass{ public static void sleep(){System.out.println("Calling Child");} } public class StaticPolymorphisam { public static void main(String[] args) ...

31. can i have a static interface

33. static interface??

The only place where you can have a static interface is when you declare an interface as a class member; in that case, the interface *must* be static. This effectively makes it a top-level interface, but means that when you use it outside the enclosing class, you must qualify the interface's name with the name of the enclosing class. i.e, public ...

34. Question - Static class vs. interface

Agreed, Satya. Given that anyone studying for the SCWCD developer can be assumed to be a SCJP, this does not appear to be the best forum for this question. Hold steady while we beam you over... Very funny, Scotty. Now beam their clothes too please - Peter PS. The specification uses interfaces almost everywhere for the same reasons that they are ...

35. Interfaces Cannot have static methods??

36. Can you have static metthods in Interfaces??

The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - ...

37. Static classes and Static interfaces

38. Static Interfaces

The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - ...

39. static variables in instantiable classes (vs abstract vs interface)

Given the following which way is the best in terms of "best practice" and speed? All of the calls work fine, but is one better than the other? The only things in any non-implementing class are static variables. Eclipse complains about instantiating a class to call a static variable and I can see why it would, but is there some benefit ...

41. Static Methods in an Interface

The implementation of a static method goes with the class, so you would have to implement it inside the interface, but as Arulk Pillai has told you, you mustn't implement methods in an interface. The whole idea of an interface is to provide functionality which is implemented differently. A static method would be implemented the same in all instances.

42. Interface static method

an interface is nothing more than a contract. For example (from the Sun tutorial web page : interface Bicycle { void changeCadence(int newValue); void changeGear(int newValue); void speedUp(int increment); void applyBrakes(int decrement); } This does nothing more that says "Hey, when people talk about a Bicycle, you can be GUARANTEED that these four methods will bet here and will look like ...

46. Can an interface define required static functions?

Since you're asking for "collective wisdom", I'll confirm that Ireneusz is completely correct here - interfaces can never declare static methods. There's no way to do this in Java. The closest options I can think of are to either refactor to make the methods non-static, or add some reflection-based code that checks at runtime to see if a given class implements ...

47. Static methods in Java Interfaces?

Simplest explanation is that methods in interfaces are by default "abstract". And we cannot have abstract static methods. But, I tried this code and it worked!!! (Can we really have static methods in interface!) public interface CoolInterface { public static final Runnable coolName = new java.lang.Runnable(){public void run(){System.out.println("static interface method alive!");}}; } public class CoolClass implements CoolInterface { public static void ...

49. Static Interface within an Inteface

51. static import only from classes and interfaces

I am a java newbie I am trying to execute a simple java program package mynack; public class FileA { public static int i=100; } import static mynack.FileA; public class FileABC { public static void main (String [] arg) { FileA S = new FileA (); System.out.println(S.i); } } Below is the Error File: C:\DR JAVA\mynack\ [line: 1] Error: ...

53. Static final in (Class or Interface)

shyamnambiar wrote: But I'm not clear . you mean to say its all the same .It does not make any difference ? The only difference that it makes (and that might be an important difference) is what you communicate with your design an intention. Constants should usually be placed within their context since that's where they are going to be used, ...

54. Static interfaces

55. No static methods for Interfaces ?

Defining a static method in a interface would be useless, since static methods can't be executed with dynamic binding. You'd have to know the name of the implementing class of the interface at compile time to call it, which would negate the need for an interface. For more details google it, that question has been asked thousands of times.

56. What is the impact if interface variables are not static finl

As you know Java has two kinds of "classes" that can be inherited; the class and the interface. Why two? The reason is the Java inheritance model. It stipulates that implementation can only be inherited from one source. So it makes sense to have on one hand the class which can carry implementation and thus can be inherited once only, and ...

58. why not static methods in an Interface

kogose, The whole concept looks pretty hackish to me. You're mixing "content" in with your actual-code. It sounds like a job for a properties file, or even a database table. I can't think of a valid reason why any String constant shouldn't be "externalised". Once externalised all the code surrounding it is "generic"... No need for verbose, hackish subclasses just to ...

59. interface type reference variable and assignment of static method

GodefridusD wrote: Arrays.asList returns a list, List, yes, which extends Collection and hence IS-A Collection. I believe I begin to understand but it does not explain my second problem... You mean "where do the implementations for the methods that I can use for variable b come from?" (I assume you meant "variable d".) The implementation comes from somewhere in the asList ...

60. static interfaces

62. Interface Vs Static Class

In my application I am keeping all the constant variable in a interface and I am implementing the interface in class and using the constant variable. In some java article I have seen that keeping all the constant variable in static class instead of interface. I am just curious to know what is the advantage here? Regards Kenny G

63. Why interface variables are public static and final

sowmya wrote: Its public coz any class can acess it. That's like saying that a car drives so it can burn fuel. static coz no need of object to call it.U can directly call . And that answers the "why" how? final coz when this variable is accessed by some class they should nt be able to change its value.Ex:PI value ...

64. why interface varaibles are static final

65. Why are the variables in an interface static and final?

What use is a blank final anyway? It's not just interfaces that don't allow it. Think about it: if a variable is final, but you leave it "blank" (whatever that means - I'm guessing you mean "without a right-hand-side assignment") what use is it? It's final, so you can't assign a value to it later. Nothing to do with interfaces, and ...

66. implement interface with static variable

Hello all I want to create a class that has a static variable. In this class I also want to create a static function to change this static value. So I donot have to create any object when change the static variable. My problem is that this class should implement an interface (using facade pattern). As it implements an interface, it ...

67. use of static refrence of interface

Hi friends, One of my program i have got a doubt. I just want to know that what is the use of static refernce of interface. I am just giving sample code. any body could tell me how is it possible? public interface X{ public void m1(); public void m2(); } I don't know where this interface has been implemented. I ...

69. Static interface Vs Static nested interface declaration

Hi, I have observed that static interface declaration is not allowed in Java. However static nested interface declaration is allowed. I could not understood reason behind this behavior. e.g. interface A{ void AA(); public static abstract interface Aa{ } } ........... this is allowed in Java. static interface d{ } ...... This is not allowed in Java... I already know that ...

70. why all fields defined in an Interface are implicitly static and final

An interface defines a contract a caller can use to use an implementation. It doesn't define how that contract should be implemented. Which member fields an implementation uses is considered an implementation detail. If you really believe that defining member fields makes sense, use an abstract class which allows you to do this.  | Contact Us | Privacy Policy
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