code: public static boolean isUnderDirectory(File child, File parent) {
          if (child == null || parent == null)
              return false;
  
          URI childUri = child.toURI();
          URI relativeUri = parent.toURI().relativize(childUri);
          return relativeUri.equals(childUri) ? false : true;
  
      }
docs: If child is under parent, will return true, otherwise, return false.
  
  @param child
  @param parent
  @return