getting"java.net.ssl.SSLException:Not trusted server certificate"

[Pailin]

package p6.android;


import android.app.Activity;
import android.os.Bundle;
//import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import org.ksoap2.SoapEnvelope;
import org.ksoap2.serialization.SoapObject;
import org.ksoap2.serialization.SoapSerializationEnvelope;
import org.ksoap2.transport.HttpTransportSE;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;

public class p6 extends Activity {

private static final String NAMESPACE = "https://192.168.0.71/hello";
private static final String URL = "https://192.168.0.71/hello/
service.asmx";
private static final String SOAP_ACTION = "https://192.168.0.71/hello/
HelloWorld";
private static final String METHOD_NAME = "HelloWorld";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
EditText TV = (EditText) findViewById(R.id.data);
TV.setText(ReceiveData());
}
String ReceiveData()
{

SoapObject resultsRequestSOAP = null;
SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME);
SoapSerializationEnvelope envelope = new
SoapSerializationEnvelope(SoapEnvelope.VER11);
envelope.dotNet=true;
envelope.setOutputSoapObject(request);
HttpTransportSE androidHttpTransport = new
HttpTransportSE(URL);
try
{
//java.net.URL url = new java.net.URL("https://192.168.0.71/hello/
service.asmx");
androidHttpTransport.call(SOAP_ACTION, envelope);
resultsRequestSOAP = (SoapObject) envelope.getResponse();
return resultsRequestSOAP.toString();

}
catch (Exception e)
{
Toast.makeText(getBaseContext(),e.toString(),
Toast.LENGTH_SHORT).show();
return e.toString();
}

}
}