public Selection(final T item){
  if (item == null) {
    this.elements=Collections.emptyList();
    this.head=null;
  }
 else {
    this.elements=Collections.singletonList(item);
    this.head=item;
  }
}

public Selection ( final T item ) { if ( item == null ) { this . elements = Collections . emptyList ( ) ; this . head = null ; } else { this . elements = Collections . singletonList ( item ) ; this . head = item ; } }
creates singleselection , with only one item in it .
