Java reflection get constructor from class name failed

Troskyvs :

I've this code snippet:

class You{
    public You(String s){}
}

public static void main(String[] args)  throws NoSuchMethodException {
    Constructor[] constructors = You.class.getConstructors();
    for(Constructor constructor: constructors){
        Class[] parameterTypes = constructor.getParameterTypes();
        for(Class c: parameterTypes){
            System.out.println(c.getName());//print java.lang.String
        }
    }
    Constructor constructor =
            You.class.getConstructor(String.class);//NoSuchMethodException?
}

This is quite old, when I print the constructors, it has one constructor with java.lang.String as parameter. But when I tried to You.class.getConstructor it says no constructor with String.class as parameter.

I'm using java1.8 on mac. Would you help to explain and how to fix?

Thanks a lot.

Jacob G. :

I'll delete this answer if it's not the case, but it looks like You is an inner class, and I suspect your actual code looks something like this:

public class Foo {

    class You {
        public You(String s){}
    }

    public static void main(String[] args)  throws NoSuchMethodException {
        Constructor[] constructors = You.class.getConstructors();

        for (Constructor constructor: constructors) {
            Class[] parameterTypes = constructor.getParameterTypes();

            for (Class c: parameterTypes){
                System.out.println(c.getName());//print java.lang.String
            }
        }

        Constructor constructor =
            You.class.getConstructor(String.class);//NoSuchMethodException?
    }
}

From the documentation of Class#getConstructor:

If this Class object represents an inner class declared in a non-static context, the formal parameter types include the explicit enclosing instance as the first parameter.

For this reason, you'll have to use the following instead:

Constructor constructor = You.class.getConstructor(Foo.class, String.class);

But obviously replace Foo with the name of your enclosing class.