private void btnNew_Click(object sender, EventArgs e) { if (Test == null) { //Test = new SimpleTCPIPClient("192.168.1.112", 8888, "ThomasPeng"); Test = new TCPIPClient("127.0.0.1", 2000, "ThomasPeng"); Test.Start(); } else { MessageBox.Show("You already opened the client station."); } }