Get hold of Foo[].class given Foo.class

Question

I have an object, c, of type Class (I get hold of the object in runtime so I can't tell in compile-time which class it represents.)

Suppose c represents the class Foo. I now want to get hold of a Class-instance which represents Foo[].

How is this done best using the standard Java API?

I think you're going to have to provide a simple example of your intention, it's not very clear from the question... — Nim, Mar 28 '12 at 13:27
http://stackoverflow.com/questions/77387/how-to-instantiate-a-java-array-given-an-array-type-at-runtime — Dave Newton, Mar 28 '12 at 13:28
yes the above will work - but if you need to do that - in majority of case you have a badly designed application (i.e. polymorphism usually handles everything you need the right way) — scibuff, Mar 28 '12 at 13:32
I'm developing something similar to a compiler and the particular use case is quite complicated. — aioobe, Mar 28 '12 at 13:38

Vlad · Accepted Answer · 2012-03-28T14:39:19.517

3

According to http://tutorials.jenkov.com/java-reflection/arrays.html, one of the ways is:

Class arrayClass = java.lang.reflect.Array.newInstance(c, 0).getClass();

This looks like a cheat, but it's definitely cleaner than playing with the class names.

edited Mar 28 '12 at 14:39

answered Mar 28 '12 at 13:32

Vlad

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score 1 · Answer 2 · answered Mar 28 '12 at 13:33

1

Here's an example of how to do this:

import java.lang.reflect.Array;
public class ReflectTest {
    public static void main(String[] args) {
        Foo c = new ReflectTest().new Foo();
        Foo[] foos = (Foo[]) Array.newInstance(c.getClass(), 5);
    }
    class Foo {
    }
}

answered Mar 28 '12 at 13:33

Paul Sanwald

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`c` is of type `Class` in my question... but I see what you're aiming at. – aioobe Mar 28 '12 at 13:35

score 0 · Answer 3 · answered Mar 28 '12 at 13:32

0

From what I can see in my test, this should work:

Class c = ...
Class cArr = java.lang.reflect.Array.newInstance(c, 1).getClass();

answered Mar 28 '12 at 13:32

Aleks G

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Get hold of Foo[].class given Foo.class

3 Answers3