I am getting the following unhandled exception
NullReferenceException was unhandled. Object reference not set to an instance of an object.
and something like warning
Field 'Project3_MineSweeper.Form3.form2' is never assigned to, and will always have its default value null
Here is the code on my DB.cs
public class DB
{
...
public DataTable GetData()
{
string spName = "GetTime";
Connection.Open();
SqlCommand command = new SqlCommand(spName, Connection);
command.CommandType = CommandType.StoredProcedure;
SqlDataReader reader = command.ExecuteReader();
DataTable dt = new DataTable();
dt.Columns.Add("Name");
dt.Columns.Add("Score");
while (reader.Read())
{
DataRow dr = dt.NewRow();
dr["name"] = Convert.ToString(reader["name"]);
dr["timeScore"] = Convert.ToInt32(reader["timeScore"]);
dt.Rows.Add(dr);
}
Connection.Close();
return dt;
}
}
And here's the code for Form3.cs
public partial class Form3 : Form
{
//THE WARNING
private Form2 form2;
public Form3()
{
InitializeComponent();
loadData();
}
public void loadData()
{
//UNHANDLED EXCEPTION HERE
DataTable dt2 = form2.db.GetData();
dgvScore.DataSource = dt2;
}
}
Lastly Form2.cs
public partial class Form2 : Form
{
public DB db;
private Form3 form3;
public Form2()
{
db = new DB();
InitializeComponent();
}
...
}
What's wrong? And what should I do to fix this problem?
you never initialize form2, which makes it cause a nullreference on this line:
DataTable dt2 = form2.db.GetData();
You should do something like
form2 = new Form2();
Depending on where you need it.
public partial class Form3 : Form
{
private Form2 form2; // <--- you never initialize form2
public Form3()
{
InitializeComponent();
loadData();
}
public void loadData()
{
//UNHANDLED EXCEPTION HERE
DataTable dt2 = form2.db.GetData();
dgvScore.DataSource = dt2;
}
}
public void loadData()
{
form2 = new Form2(); // add this line to init form2 before using
DataTable dt2 = form2.db.GetData();
dgvScore.DataSource = dt2;
}
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