Please wait screen appearing after the login button - blackberry

Question

I am trying to implement a "Wait Screen" in my BlackBerry app. The screen is to appear when the user clicks "Login" and it should go away after login has successfully been made. I am calling the screen in the "Login" listener after which I call a methd to fetch data from webs ervice. When the data is fetched, and the new screen is shown, the "Wait Screen" should disappear. However, on clicking login I get Uncaught - RuntimeException after which new screen is displayed with the "Waiting Screen" on top of it. Can somebody help me with this?
public class MessageScreen extends PopupScreen
{
private String message;
public MessageScreen (String message)
{
super( new HorizontalFieldManager(), Field.NON_FOCUSABLE);
this.message = message;
final BitmapField logo = new BitmapField(Bitmap.getBitmapResource( "cycle.gif"));
logo.setSpace( 5, 5 );
add(logo);
RichTextField rtf = new RichTextField(message, Field.FIELD_VCENTER | Field.NON_FOCUSABLE | Field.FIELD_HCENTER);
rtf.setEditable( false );
add(rtf);
}
}
I am calling this in the "Login" click event - button listener.
public void fieldChanged(Field field, int context)
{
// Push appropriate screen depending on which button was clicked
String uname = username.getText();
String pwd = passwd.getText();
if (uname.length() == 0 || pwd.length()==0) {
Dialog.alert("One of the textfield is empty!");
} else {
C0NNECTION_EXTENSION=checkInternetConnection();
if(C0NNECTION_EXTENSION==null)
{
Dialog.alert("Check internet connection and try again");
}
else
{
UiApplication.getUiApplication().invokeLater( new Runnable()
{
public void run ()
{
UiApplication.getUiApplication().pushScreen( new MessageScreen("Signing in...") );
}
} );
doLogin(uname, pwd);
}
}
}
private String doLogin(String user_id, String password)
{
String URL ="";
String METHOD_NAME = "ValidateCredentials";
String NAMESPACE = "http://tempuri.org/";
String SOAP_ACTION = NAMESPACE+METHOD_NAME;
SoapObject resultRequestSOAP = null;
HttpConnection httpConn = null;
HttpTransport httpt;
SoapPrimitive response = null;
SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME);
request.addProperty("username", user_id);
request.addProperty("password", password);
System.out.println("The request is=======" + request.toString());
SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
envelope.dotNet = true;
envelope.setOutputSoapObject(request);
httpt = new HttpTransport(URL+C0NNECTION_EXTENSION);
httpt.debug = true;
try
{
httpt.call(SOAP_ACTION, envelope);
response = (SoapPrimitive) envelope.getResponse();
String result = response.toString();
resultRequestSOAP = (SoapObject) envelope.bodyIn;
String[] listResult = split(result, sep);
strResult = listResult[0].toString();
strsessionFirstName = listResult[1].toString();
strsessionLastName = listResult[2].toString();
strsessionPictureUrl = MAINURL + listResult[3].substring(2);
strsessionStatusId = listResult[4].toString();
strsessionStatusMessage = listResult[5].toString();
strsessionLastUpdateTst = listResult[6].toString();
if(strResult.equals("credentialaccepted"))
{
if(checkBox1.getChecked() == true)
{
persistentHashtable.put("username", user_id);
persistentHashtable.put("password", password);
}
Bitmap bitmap = getLiveImage(strsessionPictureUrl, 140, 140);
StatusActivity nextScreen = new StatusActivity();
nextScreen.getUsername(user_id);
nextScreen.getPassword(password);
nextScreen.setPictureUrl(bitmap);
nextScreen.setImage(strsessionPictureUrl);
nextScreen.setFirstName(strsessionFirstName, strsessionLastName, strsessionLastUpdateTst, strsessionStatusMessage);
UiApplication.getUiApplication().pushScreen(nextScreen);
UiApplication.getUiApplication().invokeLater( new Runnable()
{
public void run ()
{
UiApplication.getUiApplication().pushScreen( UiApplication.getUiApplication().getActiveScreen() );
}
} );
}
if(strResult.equals("credentialdenied"))
{
Dialog.alert("Invalid login details.");
UiApplication.getUiApplication().pushScreen(new LoginTestScreen() );
}
} catch (IOException e) {
// TODO Auto-generated catch block
System.out.println("The exception is IO==" + e.getMessage());
} catch (XmlPullParserException e) {
// TODO Auto-generated catch block
System.out.println("The exception xml parser example==="
+ e.getMessage());
}
System.out.println( resultRequestSOAP);
//UiApplication.getUiApplication().pushScreen( UiApplication.getUiApplication().getActiveScreen() );
return response + "";
//UiApplication.getUiApplication().pushScreen(new InfoScreen());
//Open a new Screen
}

Answer 1

Like Eugen said, you should run doLogin() on a background Thread:
final String uname = username.getText();
final String pwd = passwd.getText();
Thread backgroundWorker = new Thread(new Runnable() {
public void run() {
doLogin(uname, pwd);
}
});
backgroundWorker.start();
If you do that, you'll need to use UiApplication.invokeLater() (or another similar technique) to show your screens (back on the main/UI thread). You can't leave the doLogin() method exactly as it originally was, because it makes calls to change the UI. For example, you have a couple calls to directly use pushScreen(), which should not be called (directly) from the background.
This is not ok (from the background):
UiApplication.getUiApplication().pushScreen(nextScreen);
But, this is:
UiApplication.getUiApplication().invokeLater( new Runnable()
{
public void run ()
{
UiApplication.getUiApplication().pushScreen(nextScreen);
}
} );
But, also, what is this code supposed to do? :
UiApplication.getUiApplication().pushScreen(nextScreen);
UiApplication.getUiApplication().invokeLater( new Runnable()
{
public void run ()
{
UiApplication.getUiApplication().pushScreen( UiApplication.getUiApplication().getActiveScreen() );
}
} );
This doesn't make sense to me. What are you trying to do with those lines of code?

Answer 2

I see only one issue so far - networking in the UI thread. Please put all your networ operations into another Thread.run().
You could also get more detailed error description by:
1) Navigate to home screen
2) Hold alt button and press LGLG on the keyboard
3) Explore showed event log for specific error

Answer 3

try this -
public void fieldChanged(Field field, int context)
{
// Push appropriate screen depending on which button was clicked
String uname = username.getText();
String pwd = passwd.getText();
if (uname.length() == 0 || pwd.length()==0) {
Dialog.alert("One of the textfield is empty!");
} else {
C0NNECTION_EXTENSION=checkInternetConnection();
if(C0NNECTION_EXTENSION==null)
{
Dialog.alert("Check internet connection and try again");
}
else
{
Dialog busyDialog = new Dialog("Signing in...", null, null, 0, Bitmap.getPredefinedBitmap(Bitmap.HOURGLASS));
busyDialog.setEscapeEnabled(false);
synchronized (Application.getEventLock()) {
busyDialog.show();
}
doLogin(uname, pwd);
}
}
}