Android Question StartActivity doesn't pause current activity

[DrAlex]

Hello,

I have a strange phenomenon.

In my program Main activity needs to download a file from a site protected by a username and a password. It starts LogIn activity, which opens a login window and asks the user for a username and a password. After the user enters his username and password, he clicks btnLogin button. Then btnLogin_Click subroutine starts, copies the username and the password into global variables, set the global Boolean variable blnLoginClicked to True and finishes the activity.

Here is the relevant segment of Main activity:

.....................................
Sub ShowLoginScreen

Log("In ShowLoginScreen")
StartActivity("LogIn")
' If "Log In" button was clicked, attempt to download the file.
Log ("In ShowLoginScreen: LogIn.blnLoginClicked = " & LogIn.blnLoginClicked)
If LogIn.blnLoginClicked = True Then

GetFile(strFileName, LogIn.strUsername, LogIn.strPassword)​

End If​

End Sub
...........................................

Here is the relevant segment of LogIn activity:

..............................................
Sub btnLogin_Click

Log ("In btnLogin_Click: edtUsername.Text = " & edtUsername.Text & ", edtPassword.Text = " & edtPassword.Text)
If edtUsername.Text = "" Then

Msgbox("Please enter your username", "Username, please")​

Else If edtPassword.Text = "" Then

Msgbox("Please enter your password", "Password, please")​

Else

strUsername = edtUsername.Text
strPassword = edtPassword.Text
blnLoginClicked = True
Activity.Finish​

End If​

End Sub
...................................................


I was expecting that after StartActivity("LogIn") the Main activity would pause and wait until LogIn activity finishes. Instead it continues and the log message "In ShowLoginScreen: LogIn.blnLoginClicked = False" appears in the log window even before the login window is displayed.

 

[EnriqueGonzalez]

You are using the second activity as a modal, (may be you should use a modal dialog for that) but it does not work like that, effectively some code will be paused (animations for example) but and this is a teory: between the startactivity and the activity_create some time elapses and between that time your code within showloginscreen will run.

even if that teory of mine is false, when you go back to the main activity, this one will go to the activity_Resume and not to showloginscreen.

 

[EnriqueGonzalez]

Check this library it may help you with your problem:
https://www.b4x.com/android/forum/threads/lib-betterdialogs.30739/

this one, actually stop the code within the sub and resume when receive a response.

 

[Guardian17]

In Post #9 of this thread:
https://www.b4x.com/android/forum/t...and-object-initializations.55287/#post-350256

I proved that the entire Sub in which StartActivity is used will run to completion as far as the logic of that Sub allows (to End Sub), AND THEN the First Activity runs its Activity_Pause. Only THEN does Activity_Create in the Second Activity and subsequent running of the Second Activity occur.

 

[EnriqueGonzalez]

Many thanks for clarifying that! because activity create (of the second activity) runs on the main thread it is now obvious that it holds for the sub where it was called to end.

 

[RandomCoder]

Many thanks for clarifying that! because activity create (of the second activity) runs on the main thread it is now obvious that it holds for the sub where it was called to end.

It's easy enough to fix, just remove the rest of the code after the call to StartActivity("LogIn") and move it into a different sub routine still in the Main Activity. Then on clicking the LogIn button you can call the new sub with CallSubDelayed and continue.

 

[DrAlex]

Thank you all very much for clarifying the issue. I have solved my problem by using the CustomDialog from the Dialogs library.

 

[DrAlex]

Check this library it may help you with your problem:
https://www.b4x.com/android/forum/threads/lib-betterdialogs.30739/

this one, actually stop the code within the sub and resume when receive a response.

Just switched to BetterDialogs' CustomDialog. It's much better!