Android Question how to manage object activity into class?

Roberto P. · May 31, 2014

I ask for help to understand how to manage the need for a dialogue between a module with a class activity.
I mean, I've created a module-type activity to manage the interface and a class to implement its management (business logic).
I can not "pass" the object activity within the class to handle its members. as in C + +, I would like to pass a pointer \ reference class in generic class activity.
I hope I have explained clearly.
thanks

DonManfred · May 31, 2014

B4X:

Private Sub Class_Globals
  Private Callback As Object
  Private Event As String
end sub
Public Sub Initialize(CallbackModule As Object, EventName As String)
  Callback = CallbackModule
  Event = EventName

you now have a reference to the activity in which this class-instance is initialized... And you have the eventname which should be fired in class...

So later in your class you then can use this to call a event in the calling activity with

B4X:

  If SubExists(Callback,Event&"_UpdateComplete") Then
      CallSub(Callback,Event&"_UpdateComplete")
  End If

You can leave out the event-thing... and just use

B4X:

CallSub(Callback,"subname")

but it is probably always better to do a
SubExists-call first...

Roberto P. · May 31, 2014

hello DonManfred,
Thank you very much, now I try to follow your advice.
Can I access to the members of the Activity?

thanks again
rp

DonManfred · May 31, 2014

you can create a sub in activity and call this sub from your class.The sub has all permissions on using or changing members and properties
What exactly you want archieve?

Roberto P. · May 31, 2014

For example, I have two members in the class activity: number and date
the generic class I would like to access the members of the class activity and manage the data of these members (variables or other objects).

So here in practice

after creating

Private mCallback As Object

Public Sub Initialize (CallbackModule As Object ...)

mCallback = CallbackModule

end sub

sub Test()
mCallback.Numero = xxx
mCallback.Data = yy

end sub

I think you have to make do with my cast the generic object or activity here does not work like that?!

thanks

DonManfred · May 31, 2014

B4X:

If SubExists(Callback,"SetNumero") Then
  CallSub2(Callback,"SetNumero", 1)
End If

and in activity-code

B4X:

Sub SetNumero(value As Int)
    numero = value
End Sub

you can do same with data

DonManfred · May 31, 2014

Maybe you should move numero and data members to your class.... And if the activity needs this value it get it from the class...

Roberto P. · May 31, 2014

very well! if I want to read data from the parent class?
thank you very much, you've been to help

DonManfred · May 31, 2014

Roberto P. said:
very well! if I want to read data from the parent class?
thank you very much, you've been to help

You should provide more details. Actually i dont think i have understand what you want to archieve here

Roberto P. · May 31, 2014

I counter-example:

activity in class I create the function that returns me the number
Sub GetNumber ()
return mNumer
end Sub

how do I call the function and return me the value

CallSub2 (Callback, "getNumber"??)

I hope it is clear

DonManfred · May 31, 2014

No, it´s not clear... from where (activity or class) you want to get this returnvalue (activity or class)?

Roberto P. · May 31, 2014

I have read the data from the class in the activity. Basically I have to write and read data from the class the activity.

hope was clear
HI

Roberto P. · May 31, 2014

I tried to do it this way, but by mistake

in the activity
Sub GetNumero() As String
Return eNumeroFattura.Text
End Sub

in the class
If SubExists(mCallback,"GetNumero") Then
Dim ssss As String
CallSub2(mCallback,"GetNumero", ssss)

End If

DonManfred · May 31, 2014

activity:

B4X:

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    'These variables can only be accessed from this module.
    Dim myclass As mynewclass
End Sub

Sub Activity_Create(FirstTime As Boolean)
    'Do not forget to load the layout file created with the visual designer. For example:
    'Activity.LoadLayout("Layout1")
    myclass.Initialize(Me,"MNC")
End Sub

in mynewclass:

B4X:

Sub Class_Globals
    Dim numero As Int = 0 
  Private Callback As Object
  Private Event As String
End Sub

'Initializes the object. You can add parameters to this method if needed.
Public Sub Initialize(CallbackModule As Object, EventName As String)
  Callback = CallbackModule
  Event = EventName
End Sub

'Gets or sets the numero
Sub getNumero As Int
  Return numero
End Sub

Sub setNumero(i As Int)
  numero = i
End Sub

You now can use

B4X:

Log(myclass.numero)

or

B4X:

myclass.numero = 35

to get or set numero in activity from the class...

Please note the magic behind getters and setters in classes.

LucaMs · May 31, 2014

Am I wrong or someone is developing a "generator"? Green-White-Red?

Roberto P. · May 31, 2014

LucaMs said:
Am I wrong or someone is developing a "generator"? Green-White-Red?

hello LucaMS I did not understand the question?!

LucaMs · May 31, 2014

numero should be declaread as private.

Great answers, Manfred Speedy

Roberto P. · May 31, 2014

after try. thanks again

LucaMs · May 31, 2014

Roberto P. said:
hello LucaMS I did not understand the question?!

It was only to remember to you the GREEN-WHITE-RED forum

Roberto P. · May 31, 2014

Sai che non ho ancora capitouando usare il forum italiano e quello generico?
Grazie

Android Question how to manage object activity into class?

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