forName括号内容报错的问题

Question

提示 Class<?> clz = Class.forName("A"); 报错，想咨询一下是什么原因呢，谢谢

Answer 1

package files;

public class file5 {

    public static void main(String[] args) throws Exception {
        Class clazz = Class.forName("files.file5$A");
        System.out.println(clazz.getMethods()[0]);
    }
    
    public static class A {
        public void hello() {
            System.out.println("hello world");
        }
    }

}