Nested Class Properties

Question

I am fairly new to C# and I have having problems with adding an object to a class inside a class. It keeps telling me to "Use the 'new' keyword to create an object instance".

Here is my class:

public class Info
{
    public List<SourceInfo> sourceInfo { get; set; }
}

public class SourceInfo
{
    public short id { get; set; }
    public string name { get; set; }
    public string icon { get; set; }
    public short subpage { get; set; }
    public short xpoint { get; set; }
    public short mediaPlayerId { get; set; }

    public SourceInfo(short ID, string NAME, string ICON, short SUBPAGE, short XPOINT, short MEDIAPLAYERID)
    {
        id = ID;
        name = NAME;
        icon = ICON;
        subpage = SUBPAGE;
        xpoint = XPOINT;
        mediaPlayerId = MEDIAPLAYERID;
    }

Here is my code:

    Info configSelect = new Info();

    private void btnSave_Click(object sender, EventArgs e)
    {
        try
        {
            configSelect.sourceInfo.Add (new SourceInfo(Convert.ToInt16(txtSrcId.Text),
                txtSrcName.Text, txtSrcIcon.Text, Convert.ToInt16(txtSrcSubpage.Text),
                Convert.ToInt16(txtSrcXpoint.Text), Convert.ToInt16(txtSrcMPId.Text)));

            WriteFile(configSelect);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex);
            throw;
        }

Possible duplicate of [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Aleks Andreev, Mar 15 '19 at 14:38
`Info.sourceInfo` is an object and needs an instance created...use `new`, perhaps in a constructor, as VS says — Ňɏssa Pøngjǣrdenlarp, Mar 15 '19 at 14:39
You might want to define it like this `public List sourceInfo { get; } = new List();` — juharr, Mar 15 '19 at 14:43
This was exactly my problem. Thank you. I just needed to create an instance of the list object in the constructor — Lee Anthony, Mar 15 '19 at 14:58

score 1 · Answer 1 · answered Mar 15 '19 at 15:04

Your Info class needs to be structured something like this. The "new" it's looking for is for List sourceInfo in your Info class.

public class Info
{
    private List<SourceInfo> _sourceInfo = new List<SourceInfo>();

    public List<SourceInfo> sourceInfo
    {
        get { return this._sourceInfo; }
        set { this._sourceInfo = value; } 
    }
}

Nested Class Properties

1 Answers1