使用断点时出现此错误并进入捕获异常。
httpTransport.call(SOAP_ACTION, envelope);
是不是这种httpTransport联系不应该null?
    public class MainActivity extends Activity {
TextView tv;
SoapObject request;
SoapSerializationEnvelope envelope;
HttpTransportSE androidHttpTransport;
Object result;
public String METHOD_NAME = "sum";
public String NAMESPACE = "http://ws.calculatorJava.org";
// private String SOAP_ACTION = NAMESPACE + METHOD_NAME;
public String SOAP_ACTION = "http://ws.calculatorJava.org/sum";
public static final String URL = "http://172.168.1.2:8888/CalculatotJava/services
    /Calculate.wsdl";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tv = (TextView) findViewById(R.id.textView1);
    try {
        request = new SoapObject(NAMESPACE, METHOD_NAME);
        request.addProperty("i", 5);
        request.addProperty("j", 15);
        envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
        envelope.dotNet = true;
        envelope.setOutputSoapObject(request);
        androidHttpTransport = new HttpTransportSE(URL);
        Toast.makeText(getBaseContext(), "GET", Toast.LENGTH_LONG).show();
        androidHttpTransport.call(SOAP_ACTION, envelope);
        result = envelope.getResponse();
        Toast.makeText(getBaseContext(),
                "  Result " + "\n" + result.toString(), 
                        Toast.LENGTH_SHORT)
                .show();
        // System.out.println("Result : " + result.toString());
        tv.setText("Addition : " + result.toString());
    } catch (Exception E) {
        E.printStackTrace();
        tv.setText("ERROR  " + "\n" + E.getClass().getName() + ":"
                + E.getMessage());
    }
}
 }