public static String relPath(String parent,String child){
  return relPath(Paths.get(parent),Paths.get(child));
}

public static String relPath ( String parent , String child ) { return relPath ( Paths . get ( parent ) , Paths . get ( child ) ) ; }
returns the relative path of 2 absolute file paths < br > " / a / b & / a / b / c / d - > c / d
