use the id for hash code . concode_field_sep GUID id concode_elem_sep String layer concode_field_sep boolean imageUpdate concode_elem_sep void setLayer concode_elem_sep void drawBackground concode_elem_sep Zone.Layer getLayer concode_elem_sep boolean equals concode_elem_sep GUID getId concode_elem_sep void draw concode_elem_sep void draw
int function ( ) { return id . hashCode ( ) ; }