各位帮忙,谢谢了
之前,我定义了一个class A{
private string E;
private string F;
private string G
pulic A(string e, string f, string g){
...
...
...}
getE(){}
...
...
}
然后这个class结束了
在下一个class中
class B{
private static readonly A Invalid = new A("?","?","?")
public B()
{
}
public A Search(string temp)
{
A a1;
DataTable table = new DataTable();
DataRow row = table.NewRow();
OleDbConnection conn=new OleDbConnection(@"Provider=Microsoft.Jet.OleDb.4.0;Data Source=..\..\..\test.MDB;");
string strsql="SELECT * FROM PostcodeData WHERE (Postcode=@PostCodep)";
conn.Open();
OleDbCommand mycom=conn.CreateCommand();
mycom.CommandText=strsql;
OleDbDataReader dr;
dr = mycom.ExecuteReader();
while(dr.Read())
{
row[0] = dr[0];
row[1] = dr[1];
row[2] = dr[2];
row[3] = dr[3];
row[4] = dr[4];
table.Rows.Add(row);
}
if (table.Rows != null)
{
return a1 = new A((string)row[0],(string)row[1],(string)row[2])
}
else
{
return Invalid;
}
}
然后再form中调用这个method
就是
private void textBox1_TextChanged(object sender, System.EventArgs e)
{
A a2;
B b1 = new B();
try
{
a2 = b1.Search(textBox1.Text);
this.x1.Text = ad.getE();
this.x2.Text = ad.getF();
this.x3.Text = ad.getG();
}
catch(Exception exception1)
{
MessageBox.Show(exception1.Message,"Error",MessageBoxButtons.OK,MessageBoxIcon.Error);
}
}
但是,当我在运行时,textbox改动之后,却出现了至少有一个参数没有指定值。。
请问,只是为什么?
我没有办法了