如何在java中实现二维链表？

public class Node {
    int data;
    Node right;
    Node down;

    public Node(int data) {
        this.data = data;
        this.right = null;
        this.down = null;
    }
}

public class TwoDLinkedList {
    Node head;

    public void insertRow(int[] rowData) {
        Node newRow = null;
        Node temp = null;

        for (int i = 0; i < rowData.length; i++) {
            Node newNode = new Node(rowData[i]);

            if (newRow == null) {
                newRow = newNode;
            } else {
                temp.right = newNode;
            }

            temp = newNode;
        }

        if (head == null) {
            head = newRow;
        } else {
            Node lastRow = head;
            while (lastRow.down != null) {
                lastRow = lastRow.down;
            }
            lastRow.down = newRow;
        }
    }

    public void display() {
        Node row = head;
        while (row != null) {
            Node node = row;
            while (node != null) {
                System.out.print(node.data + " ");
                node = node.right;
            }
            System.out.println();
            row = row.down;
        }
    }
}

public class Main {
    public static void main(String[] args) {
        TwoDLinkedList list = new TwoDLinkedList();
        list.insertRow(new int[]{1, 2, 3});
        list.insertRow(new int[]{4, 5, 6});
        list.insertRow(new int[]{7, 8, 9});

        list.display();
    }
}