private void btUpdate_Click(object sender, EventArgs e) { int i = lbTopic.SelectedIndex; if (i == -1) { MessageBox.Show("Select a topic to change"); return; } else { string oldTopicID = topicList[i].TopicID; BOTopic bot = new BOTopic(); Topic t = new Topic(txtTopicID.Text, txtTopicName.Text); bool success =bot.Update(t, oldTopicID); if (success) { MessageBox.Show("Update topic success!"); loadTopicList(); } else MessageBox.Show("Failed to update a topic!"); txtTopicID.Clear(); txtTopicName.Clear(); btUpdate.Enabled = false; btDelete.Enabled = false; loadTopicList(); } }