XSelection(XAtom atom){
  if (atom == null) {
    throw new NullPointerException("Null atom");
  }
  selectionAtom=atom;
  table.put(selectionAtom,this);
}

XSelection ( XAtom atom ) { if ( atom == null ) { throw new NullPointerException ( "Null atom" ) ; } selectionAtom = atom ; table . put ( selectionAtom , this ) ; }
creates a selection object .
