public void add(Song song){
        int pos = song.hashCode() % this.length;
        ListElement node = new ListElement(song,null);
        if(this.entries[pos]==null){
            this.entries[pos] = node;
        }else {
            this.entries[pos].setNext(node);
        }

    }




  public Song lookupTitle(String titel) {

        int pos = titel.hashCode() % this.length;


        ListElement node = this.entries[pos];

        while(node != null) {

            if(node.getValue().getTitel().equals(titel)) {
                return node.getValue();
            }
            node = node.getNext();
        }
        return null;
    }