JAVA question add code in ???

Determine whether a placement string is well-formed: 1.it consists of exactly N three-character piece placements (where N = 1 .. 8); 2.each piece placement is well-formed 3.no shape appears more than once in the placement   @param placement A string describing a placement of one or more pieces  @return True if the placement is well-formed  static boolean Placement(String placement) { ???  return false; }