调用数据库的查询方法在button按钮事件里调用正常,在combox的indexchange事件里调用时就报错,未将对象引用设置到对象的实例
public void SelectClassInfo()
{
Entity.ClassInfo[] myClassInfo = new Entity.ClassInfo[3];
// 在cmbClassno_SelectedIndexChanged中调用时会报错,未将对象引用设置到对象的实例
myClassInfo = myclass.GetClassInfo(StrCmb );
if (myClassInfo != null)
{
for (int i = 0; i < myClassInfo.Length; i++)
{
this.txtCollegeId.Text = myClassInfo[i].CollegeId.ToString();
this.txtClassName.Text = myClassInfo[i].ClassName.ToString();
}
}
}
-------------------------
//正常
private void btnSelect_Click(object sender, EventArgs e) //获取信息
{
//this.SelectClassInfo();
}
// 会报错,
private void cmbClassno_SelectedIndexChanged(object sender, EventArgs e)
{
this.SelectClassInfo();
}
public void SelectClassInfo()
{
Entity.ClassInfo[] myClassInfo = new Entity.ClassInfo[3];
// 在cmbClassno_SelectedIndexChanged中调用时会报错,未将对象引用设置到对象的实例
myClassInfo = myclass.GetClassInfo(StrCmb );
if (myClassInfo != null)
{
for (int i = 0; i < myClassInfo.Length; i++)
{
this.txtCollegeId.Text = myClassInfo[i].CollegeId.ToString();
this.txtClassName.Text = myClassInfo[i].ClassName.ToString();
}
}
}
-------------------------
//正常
private void btnSelect_Click(object sender, EventArgs e) //获取信息
{
//this.SelectClassInfo();
}
// 会报错,
private void cmbClassno_SelectedIndexChanged(object sender, EventArgs e)
{
this.SelectClassInfo();
}
Entity.ClassInfo[] myClassInfo = new Entity.ClassInfo[3];
// 到下面这行就报错,未将对象引用设置到对象的实例
myClassInfo = myclass.GetClassInfo(StrCmb );
是调用BULayer里的方法