import class file in java

I have a main directory (contains main.java) and a subdirectory( contains child.java).

My problem is how to instantiate child.java in main.java

1. I have made the child class public. & added the line#1 as package mypackage
2. I have compiled child.class with javac -d . child.java which creates a new mypackage directory.
3. I tried to import child class in main as follows: import subdirectory.mypackage.* (note -d option places the child.class inside mypackage folder)
4. I compiled the main.java file with "javac main.java"

I get the following error:

mainAESE.java:9: cannot access subdirectory.child
bad class file: RegularFileObject[./subdirectory/child
class file contains wrong class: mypackage.child
Please remove or make sure it appears in the correct subdirectory of the class
child childInstance= new child();
^
1 error

please help me!!