题解 | #合并两个排序的链表#

获取节点的值，进行排序，之后重新构建链表，注意构建链表时，引入第三变量。

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
import java.util.ArrayList;
import java.util.Collections;
public class Solution {
    public ListNode Merge(ListNode list1,ListNode list2) {
      if (list1 == null && list2 == null) {return  null;}
        if (list1 == null && list2 != null) {return  list2;}
        if (list1 != null && list2 == null) {return  list1;}
        ArrayList<Integer> list = new ArrayList<>();

        while (list1 != null) {
            list.add(list1.val);
            list1 = list1.next;
        }
        while (list2 != null) {
            list.add(list2.val);
            list2 = list2.next;
        }
        Collections.sort(list);



//        ListNode result = null;
        ListNode result = new ListNode(list.get(0));
        ListNode re = result;

        for (int i = 1; i < list.size(); i++) {
            ListNode node = new ListNode(list.get(i));
            result.next = node;
            result = result.next;
        }


//        for (Integer integer : list) {
//            ListNode node = new ListNode(integer);
//            result = node;
//            result = result.next;
//        }

        return re;

    }
}