How to dismiss automatic ?

i want to simulate a loading with this dialog.. i call a function inside pre execute asynctask and in post execute the same dialog dismiss .. how can i do that ?

im trying but no sucess.. someone can help me ?

public class Helper_Functions_Dialogs
{
public static WeakReference ProgressDialogGeral;

//region Loading
public static void LoadingScreen(boolean show, String Titulo,String Mensagem, Activity activity) {

if(ProgressDialogGeral == null)
ProgressDialogGeral = new WeakReference(new
MaterialStyledDialog.Builder(activity).build());

if(show)
{
ProgressDialogGeral.get().getBuilder()
.setHeaderDrawable(R.drawable.header_dialog)
.setTitle(Titulo)
.setCancelable(false)
.withDialogAnimation(true)
.setPositiveText("Load...")
.setDescription(Mensagem);

ProgressDialogGeral.get().show();
}
else
{
ProgressDialogGeral.get().dismiss();
ProgressDialogGeral = null;
}
}
}

The dialog not dismissing

Start with the Java Helper_Functions_Dialogs snippet in the issue and reproduce the loading flow around the AsyncTask pre-execute and post-execute callbacks. Confirm the expected dialog lifecycle and verify that the dialog is dismissed reliably after the asynchronous work completes.

Written by the indexing model from the issue text.