Can we create public static abstract class in java?

Question

I was searching in google for something and I got a code like

public static abstract class LocationResult{
    public abstract void gotLocation(Location location);
}

It's a nested class but wondering how it could be accessible ?

You can check it out here http://stackoverflow.com/questions/4579305/can-we-instantiate-abstract-class — Shahzad Imam, Sep 13 '12 at 09:37

score 27 · Accepted Answer · edited Nov 29 '12 at 17:24

27

It must be a nested class: the static keyword on the class (not methods within it) is only used (and syntactically valid) for nested classes. Such static member classes (to use Java in a Nutshell's common nomenculture) hold no reference to the enclosing class, and thus can only access static fields and methods within it (unlike non-static ones; see any summary of nested classes in Java (also known as inner classes).

It can be accessible like this:

public class EnclosingClass {
  public static abstract class LocationResult{
    public abstract void gotLocation(Location location);
  }
}

EnclosingClass.LocationResult locationResult = ...

edited Nov 29 '12 at 17:24

Stuart Rossiter

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answered Sep 13 '12 at 09:30

David Rabinowitz

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Or it could be extended by other nested classes. – assylias Sep 13 '12 at 09:32
as a newbie i learn we can not create an instance of a abstract class.is there any documentation of material to learn this? – Yasir Khan Sep 13 '12 at 09:34
@YasirKhan You can in the form of an anonymous class. – assylias Sep 13 '12 at 09:35
1

@Yasir - like any other abstract class, you need to inherit and create a concrete subclass whom you can instantiate. A variable can be of the type of the superclass, and hold a reference to the subclass - this is called upcasting. – David Rabinowitz Sep 13 '12 at 09:37
@DavidRabinowitz why we are using static keyword here? – Yasir Khan Sep 13 '12 at 10:02
@YasirKhan I edited the answer to better explain why the static keyword is there. – Stuart Rossiter Nov 30 '12 at 12:26

score 4 · Answer 2 · answered Sep 13 '12 at 09:31

Only nested classes can be static. By doing so you can use the nested class without having an instance of the outer class.

So you could create a class extending it using extends Mainclass.LocationResult and use it with Mainclass.LocationResult instance = ...

Can we create public static abstract class in java?

2 Answers2