Static array with inheriting classes in Java

Question

I have a litte problem with a static, direct filled array of class files, which inheriting from a superclass

 public static Class<SuperClass> classes= new Class<SuperClass>[]{
    ChildClass.class
}

seems to be impossible. Intellij says, it requires the Superclass.class, instead of ChildClass.class.

Why is this not possible? Thank you

You are assigning an array to a non-array variable.

Jeffrey
– Jeffrey

2013-06-28 14:16:50 +00:00
Commented Jun 28, 2013 at 14:16 — Jeffrey
– Jeffrey, Commented Jun 28, 2013 at 14:16

Tom Hawtin - tackline · Accepted Answer · 2013-06-28 14:24:24Z

1

Arrays and generics don't mix.

Also a type Xx<Derived> is not assignable to Xx<Base> (see bazillions of questions on this site).

You may want:

private static final Class<? extends SuperClass> clazz = ChildClass.class;

The other way around:

private static final Class<? super ChildClass> clazz = SuperClass.class;

Or use an appropriate collection:

private static final Set<? extends SuperClass> classes =
    unmodifiableSet(singleton(
        ChildClass.class
    ));

Mutable statics, even if not public, are a really bad idea.

edited Jun 28, 2013 at 14:24

answered Jun 28, 2013 at 14:18

Tom Hawtin - tackline

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Comments

Ruchira Gayan Ranaweera · Accepted Answer · 2013-06-28 14:20:43Z

0

It is not possible because we use =(equal) to say left and right hand sides are same.. here you are assigning an array to a non-array variable.

answered Jun 28, 2013 at 14:20

Ruchira Gayan Ranaweera

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Comments

gustavohenke · Accepted Answer · 2013-06-28 14:42:18Z

0

There are no generic arrays. You cannot create an array of Class
Class is not a subclass of Class

edited Jun 28, 2013 at 14:42

gustavohenke

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answered Jun 28, 2013 at 14:24

avidD

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1 Comment

Marian Klühspies Over a year ago

Thank you. The reason why i need this is the following: I have several filters and I need to define, which filter classes my program is allowed to use. maybe I should just put them as objects into an array on startup or something...

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