@Override
    public boolean contains(U unit) {

        for (Item<?> item : this.getTotalLength()) {
            if (item.getUnit().equals(unit)) {
                return (item.getAmount() > 0);
            }
        }

        return false;

    }
@ Override public boolean contains ( U unit ) { for ( Item < ? > item : this . getTotalLength ( ) ) { if ( item . getUnit ( ) . equals ( unit ) ) { return ( item . getAmount ( ) > 0 ) ; } } return false ; }
~ Methoden ----------------------------------------------------------