Java实现两个有序的链表合并

实现两个有序链表的和并，就是将两个链表按照一定的顺序合并成一个链表即可

目标：
单向链表1：SingleLinkedList:[0, 2, 4, 6, 8]
单向链表2：SingleLinkedList:[1, 3, 5, 7, 9, 11]
合并后链表mergedNode:[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11]

代码实现：

        SingleLinkedList sll1 = new SingleLinkedList();
        for (int i = 0; i < 10; i += 2) {
            SingleNode node = new SingleNode(i, null);
            sll1.add(node);
        }
        System.out.println("单向链表1：" + sll1.toString());

        SingleLinkedList sll2 = new SingleLinkedList();
        for (int i = 1; i < 12; i += 2) {
            SingleNode node = new SingleNode(i, null);
            sll2.add(node);
        }
        System.out.println("单向链表2：" + sll2.toString());

    public SingleNode mergeTwoLists(SingleNode l1, SingleNode l2) {
        if (l1 == null) {
            return l2;
        }
        if (l2 == null) {
            return l1;
        }
        SingleNode mergedNode;
        if (l1.getItem() < l2.getItem()) {
            mergedNode = l1;
            mergedNode.next = mergeTwoLists(l1.next, l2);
        } else {
            mergedNode = l2;
            mergedNode.next = mergeTwoLists(l2.next, l1);
        }
        return mergedNode;
    }