Serialize and DeSerialize of N-Array Tree

NArrayTreeSerDe

//Class Represent NArrayTreeNode
public class NArrayTreeNode<E> {
    private E data;
    private List<NArrayTreeNode<E>> childs = new ArrayList<>();

    public NArrayTreeNode(E data) {
        this.data = data;
    }

    public NArrayTreeNode<E> addChild(NArrayTreeNode<E> child){
        this.childs.add(child);
        return this;
    }


    public List<NArrayTreeNode<E>> getChilds() {
        return childs;
    }

    public E getData() {
        return data;
    }

    @Override
    public String toString() {
        StringBuilder builder=new StringBuilder();
        builder.append(data.toString());
        for(NArrayTreeNode child:childs){
            builder.append(child.toString());
        }
        return builder.toString();
    }
}
//TreeDeSerializer Interface
public interface TreeDeSerialize<E> {
    E deserialize(String value);
}
//TreeSerializer Interface
public interface TreeSerialize<E> {
    String serialize(E e);
}

public class NArrayTreeSerDe<E> {
    private TreeDeSerialize<E> deSerialize;
    private TreeSerialize<E> serialize;
    private static final String MARKER= "#";

    public NArrayTreeSerDe(TreeDeSerialize<E> deSerialize, TreeSerialize<E> serialize) {
        this.deSerialize = deSerialize;
        this.serialize = serialize;
    }


    public String serialize(NArrayTreeNode<E> root) {
        StringBuilder sb = new StringBuilder();
        String seperator="";
        buildString(root,sb,seperator);
        return sb.toString();
    }


    private void buildString(NArrayTreeNode<E> node, StringBuilder sb, String seperator) {
        if (node == null) {
            return;
        }
        String str = serialize.serialize(node.getData());
        sb.append(seperator).append(str);
        for(NArrayTreeNode<E> child:node.getChilds()){
            buildString(child,sb,",");
        }
        sb.append(",").append(MARKER);
    }


    public NArrayTreeNode<E> deserialize(String data, String seperator) {
        Deque<String> nodes = new LinkedList<>();
        nodes.addAll(Arrays.asList(data.split(seperator)));
        return buildTree(nodes);
    }

    private NArrayTreeNode<E> buildTree(Deque<String> nodes) {
        String val = nodes.remove();
        if (val.equals(MARKER)) return null;
        NArrayTreeNode<E> node = new NArrayTreeNode<>(deSerialize.deserialize(val));
        while (!nodes.isEmpty()){
            NArrayTreeNode<E> child = buildTree(nodes);
            if(child!=null)
                node.addChild(child);
            else
                break;
        }
        return node;
    }
}