Question

I have a nested static class like:

package a.b
public class TopClass {

    public static class InnerClass {
    }
}

I want to instantiate with Class.forName() but it raises a ClassNotFoundException .

Class.forName("a.b.TopClass"); // Works fine.
Class.forName("a.b.TopClass.InnerClass"); // raises exception

TopClass.InnerClass instance = new TopClass.InnerClass(); // works fine

What is wrong in my code?

Udo.

Answer 1

Nested classes use “$” as the separator:

Class.forName("a.b.TopClass$InnerClass");

That way the JRE can use dots to determine packages, without worrying about nested classes. You’ll spot this if you look at the generated class file, which will be TopClass$InnerClass.class.

(EDIT: Apologies for the original inaccuracy. Head was stuck in .NET land until I thought about the filenames…)