Question

我有一个程序，在其中使用组合框导航嵌套的数据结构。这些组合框应使用数据结构中的属性作为其显示成员。

我将表单构造函数中所有组合框的成员绑定

    public frmWeatherManager()
    {
        InitializeComponent();

        cmbLocationSelect.DisplayMember = "NameCmbBoxInterface";
        cmbLocationSelect.ValueMember = "YearCmbBoxInterface";

        cmbYearSelect.DisplayMember = "NumCmbBoxInterface";
        cmbYearSelect.ValueMember = "this";

        cmbMonthSelect.DisplayMember = "IdCmbBoxInterface";
        cmbMonthSelect.ValueMember = "this";
    }

“ NameCmbBoxInterface”和其他类似的属性只是在这里充当私有成员的代理。

    private string Name;
    private string StreetName;
    private string County;
    private string PostCode;
    private double Latitude;
    private double Longitude;
    private Year[] Years;

    public string NameCmbBoxInterface
    {
        get
        {
            return Name;
        }
        set
        {
            Name = value;
        }
    }

由于老师的限制，我不得不这样做。我不允许使用任何“内置”功能。这意味着我必须自己编写getter和setter，并且不能使用.contains（）之类的列表或方法。

我通过两种方式填充数据结构：

第一种方法是生成随机数据的地方。

    private void btnPopulate_Click(object sender, EventArgs e)
    {
        Locations = new Location[3];

        Locations[0] = new Location("location1", "england", "street1", "postcode1", 0.55, 2.74, year_populate("Location1"));
        Locations[1] = new Location("location2", "england", "street2", "postcode2", 1.45, -0.70, year_populate("Location2"));
        Locations[2] = new Location("location3", "england", "street3", "postcode3", 7.37, -1.40, year_populate("Location3"));

        cmbLocationSelect.DataSource = Locations;
    }

这很好，并且位置选择器组合框正确显示了“ location1”，“ location2”，“ location3”。

我还有另一个功能可以从文件中读取数据：

    private void btnReadFile_Click(object sender, EventArgs e)
    {
        System.IO.StreamReader file = new System.IO.StreamReader(txtFilePath.Text);

        //establish the number of locations to be parsed.
        int locationcount = int.Parse(file.ReadLine());

        //initalize locations array to the required size
        Locations = new Location[locationcount + 1];

        for (int i=0; i < locationcount; i++)
        {
            //begin location parse
            //i is used to control access to location array

            //extract data and sort into containers ready for insertion into data structure.

            string locationName = file.ReadLine();
            string streetName = file.ReadLine();
            string county = file.ReadLine();
            string postCode = file.ReadLine();
            double latitude = double.Parse(file.ReadLine());
            double longitude = double.Parse(file.ReadLine());

            //establish number of years in location to be parsed
            //must be done first so that location object's year array knows how large it needs to be
            int yearcount = int.Parse(file.ReadLine());

            //create new location object inside array.
            Locations[i] = new Location(locationName, streetName, county, postCode, latitude, longitude, yearcount);

            for (int R=0; R < yearcount; R++)
            {
                //begin year parse

                string desc = file.ReadLine();
                int yearid = int.Parse(file.ReadLine());

                //create current year object
                Year thisyear = new Year(yearid, desc);

                for(int M=0; M < 12; M++)
                {
                    //begin month parse
                    int monthid = int.Parse(file.ReadLine());
                    double maxtemp = double.Parse(file.ReadLine());
                    double mintemp = double.Parse(file.ReadLine());
                    int frostdays = int.Parse(file.ReadLine());
                    double rainfall = double.Parse(file.ReadLine());
                    double sunshine = double.Parse(file.ReadLine());

                    //read out useless year id line unless we are on the last loop
                    if (M != 11)
                        file.ReadLine();

                    //create current month object
                    Month thismonth = new Month(monthid, frostdays, maxtemp, mintemp, rainfall, sunshine);

                    //add month in question to the correct place in the year object.
                    thisyear.SetMonth(thismonth, M);
                }

                //similarly add year to location.
                Locations[i].SetYear(thisyear, R);
            }
        }
        file.Close();

        //now that we are all done. Bind the data source of the combo box
        cmbLocationSelect.DataSource = Locations;
    }

在这种情况下，它将失败。位置选择器组合框显示Location对象的每个实例的.tostring评估。我已经知道，当找不到您想要绑定到显示值的成员时会发生这种情况。

我已经花了好几个小时了，但我看不到什么可能引起问题。我希望有人能分享一些见识。

c＃组合框在一种情况下无法绑定显示成员，但在另一种情况下成功

0 个答案: