Question

问题出在else的情况下，我已经对问题行进行了评论

    static void Main(string[] args)
    {
        XMLData xmldataExample = new XMLData();
        Usergaz usergazExample = new Usergaz();
        UsergazItem usergazitemExample = new UsergazItem();

        UsergazItem item = new UsergazItem();
        string filename = @"C:\Users\565133\Desktop\test.xml";
        Deserialize<XMLData> deserializeobj = new Deserialize<XMLData>();
        Console.WriteLine("Choose \n1.Serialization\n2.Deserialization\n3.Deserialize only a token");

        //It works when I give tknid input line here
        int inp = Console.Read();
        string tknid = Console.ReadLine();//It doesn't work if I get tknid input here

        if (inp == 1)
        {
            usergazitemExample.getusergazitem();

            usergazExample.getusergaz();
            usergazExample.gazitem.Add(usergazitemExample);

            xmldataExample.getxmldata();
            xmldataExample.gazset.Add(usergazExample);


            serial(xmldataExample, filename);
            Console.WriteLine("Its done");
            Console.ReadKey();

        }
        else if (inp == 2)
        {
            Console.WriteLine("Getting data from xml file");

           // Deserialize<XMLData> deserializeobj = new Deserialize<XMLData>();
            xmldataExample = deserializeobj.deserializefunction(filename);
            List<Usergaz> samplelist = new List<Usergaz>();
            samplelist = xmldataExample.gazset;

            MTable.initialize();
            MTable.usergazzetterset.Add(xmldataExample.updatedtime, samplelist);
            Console.WriteLine("Deserialization complete, check the object");
            Console.ReadKey();
        }

在其他情况下，我使用tknid进行过滤，但即使在我从用户输入tknid之前，我也会得到null引用异常，说'item'对象为null。我得到了指向Console.WriteLine Line的异常

        else
        {
            //Console.WriteLine("Getting only a specific token Enter the token id");
            //string tknid;
            //tknid = Console.ReadLine(); 
//I intended to give tknid input here, but I cannot do it...
            //Console.WriteLine(tknid);
            //Console.ReadKey();
            //string tknid = "3"; Initializing tknid with this statement works fine




            item = deserializeobj.deserializefunction(filename).gazset[0].gazitem.Where(X => X.id == tknid).FirstOrDefault();

            Console.WriteLine("The value for the token id {0} is {1}", tknid,item.val);

            Console.ReadKey();

        }
    }

Answer 1

我已经得到了解决方案，问题不在于if..else语句，它与Console.Read（）有关。

我将SELECT posts.id , posts.cat_id , posts.school_id , posts.campus_id , posts.status , posts.priority , posts.title , posts.content , posts.phone , posts.email , posts.tags , posts.zip , posts.price_new , posts.price_old , posts.reviewed_by , posts.reviewed_date , posts.updated_date , posts.posted_date , posts.expired_date , posts.ip_address , schools.school_name, campuses.campus_name , meta.meta_key , meta_value , images.img_name FROM posts LEFT JOIN meta ON posts.id = meta.post_id LEFT JOIN images ON posts.id = images.post_id LEFT JOIN schools ON posts.school_id = schools.id LEFT JOIN campuses ON posts.campus_id = campuses.id ORDER BY posts.updated_date DESC LIMIT 10替换为int inp = Console.Read()，但效果很好。

现在，我了解int inp = int.Parse(Console.ReadLine())如何在我在下面分享的答案的帮助下工作，但我永远不会尝试使用Console.Read()，并始终使用Console.Read()。

Console.ReadLine()如何运作：

https://stackoverflow.com/a/10318917/7114583

输入引起nullreferenceexception的字符串的错误是什么？

1 个答案: