C＃变量问题

Question

Having problems with some c# variables. Can't figure out what i'm doing wrong. Probably something simple but i've been at it for a bit.

public class DataFileLoad
{
    //Public jagged array variables

    public string[][] aConfJag = null;
    public string[][] aPartJag = null;
    public string[][] aTypeJag = null;
    public string[][] aWkshpJag = null;
    public string[][] aWorkJag = null;

    public void loadFiles()
    {
        //The path of our exectuable
        string exePath = Application.StartupPath;

        //Set our working directory to our exe path for file reading
        Directory.SetCurrentDirectory(exePath);

        string[] aConferences = File.ReadAllLines(@"DATA\CONFERENCES.txt");
        string[] aParticipants = File.ReadAllLines(@"DATA\PARTICIPANTS.txt");
        string[] aType = File.ReadAllLines(@"DATA\TYPE.txt");
        string[] aWkshpReg = File.ReadAllLines(@"DATA\WKSHP_REGISTRATIONS.txt");
        string[] aWorkshops = File.ReadAllLines(@"DATA\WORKSHOPS.txt");

        //Make our arrays jagged for easier processing
        string[][] aConfJag  = aConferences.Select(line => line.Split(',').ToArray()).ToArray();
        string[][] aPartJag  = aParticipants.Select(line => line.Split(',').ToArray()).ToArray();
        string[][] aTypeJag  = aType.Select(line => line.Split(',').ToArray()).ToArray();
        string[][] aWkshpJag = aWkshpReg.Select(line => line.Split(',').ToArray()).ToArray();
        string[][] aWorkJag  = aWorkshops.Select(line => line.Split(',').ToArray()).ToArray();
    }
}

And when I try to access the variables from another class they come up as null and it throws an exception.

public void updateFormData()
{
    //Participant Type
    var data = new DataFileLoad();
    data.loadFiles();
    foreach(string[] e in data.aTypeJag)
    {
        MessageBox.Show(e[1]);
        comboConference.Items.Add(e[1]);
    }
}

 System.NullReferenceException was unhandled HResult=-2147467261 Message=Object reference not set to an instance of an object. Source=FBLA_App 

Is what I get. Thoughts? Not quite sure why i'm getting null variables.

Answer 1

The problem is that you are defining new variables inside the loadFiles method.

Do this instead:

public class DataFileLoad
{
    //Public jagged array variables
    public string[][] aConfJag = null;
    public string[][] aPartJag = null;
    public string[][] aTypeJag = null;
    public string[][] aWkshpJag = null;
    public string[][] aWorkJag = null;

    public void loadFiles()
    {
        //The path of our exectuable
        string exePath = Application.StartupPath;

        //Set our working directory to our exe path for file reading
        Directory.SetCurrentDirectory(exePath);

        string[] aConferences = File.ReadAllLines(@"DATA\CONFERENCES.txt");
        string[] aParticipants = File.ReadAllLines(@"DATA\PARTICIPANTS.txt");
        string[] aType = File.ReadAllLines(@"DATA\TYPE.txt");
        string[] aWkshpReg = File.ReadAllLines(@"DATA\WKSHP_REGISTRATIONS.txt");
        string[] aWorkshops = File.ReadAllLines(@"DATA\WORKSHOPS.txt");

        //Make our arrays jagged for easier processing
        aConfJag  = aConferences.Select(line => line.Split(',').ToArray()).ToArray();
        aPartJag  = aParticipants.Select(line => line.Split(',').ToArray()).ToArray();
        aTypeJag  = aType.Select(line => line.Split(',').ToArray()).ToArray();
        aWkshpJag = aWkshpReg.Select(line => line.Split(',').ToArray()).ToArray();
        aWorkJag  = aWorkshops.Select(line => line.Split(',').ToArray()).ToArray();
    }
}

I would also strongly recommend that you do NOT expose these variables as is. Encapsulate them in readonly properties instead so that their value cannot be changed from outside the DataFileLoad class.

Answer 2

you're "hiding" the class fields by re-declaring them. just take off the declaration:

    //Make our arrays jagged for easier processing
    aConfJag  = aConferences.Select(line => line.Split(',').ToArray()).ToArray();
    aPartJag  = aParticipants.Select(line => line.Split(',').ToArray()).ToArray();
    aTypeJag  = aType.Select(line => line.Split(',').ToArray()).ToArray();
    aWkshpJag = aWkshpReg.Select(line => line.Split(',').ToArray()).ToArray();
    aWorkJag  = aWorkshops.Select(line => line.Split(',').ToArray()).ToArray();

Answer 3

Change

        string[][] aConfJag  = aConferences.Select(line => line.Split(',').ToArray()).ToArray();
        string[][] aPartJag  = aParticipants.Select(line => line.Split(',').ToArray()).ToArray();
        string[][] aTypeJag  = aType.Select(line => line.Split(',').ToArray()).ToArray();
        string[][] aWkshpJag = aWkshpReg.Select(line => line.Split(',').ToArray()).ToArray();
        string[][] aWorkJag  = aWorkshops.Select(line => line.Split(',').ToArray()).ToArray();

to

       aConfJag  = aConferences.Select(line => line.Split(',').ToArray()).ToArray();
       aPartJag  = aParticipants.Select(line => line.Split(',').ToArray()).ToArray();
       aTypeJag  = aType.Select(line => line.Split(',').ToArray()).ToArray();
       aWkshpJag = aWkshpReg.Select(line => line.Split(',').ToArray()).ToArray();
       aWorkJag  = aWorkshops.Select(line => line.Split(',').ToArray()).ToArray();

You were creating new variable rather than assigning them to you class level variables