Android Question Date stuck on 25-10-2020.

AHilberink · Oct 24, 2020

Hi,

I have a strange behaviour, I cannot explain. I use a button Up and a button Down to increase/decrease the date with one day:

B4X:

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    Dim DisplayDatum As String
    Private edtDate As EditText
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Activity.LoadLayout("Layout")
    DateTime.DateFormat="dd-MM-yyyy"
    DisplayDatum=DateTime.Date(DateTime.Now)
    edtDate.Text=DisplayDatum
End Sub

Sub Activity_Resume

End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

Sub btnDDmin_Click
    DisplayDatum=DateTime.Date(DateTime.DateParse(DisplayDatum)-DateTime.TicksPerDay*1)
    edtDate.Text=DisplayDatum
End Sub

Sub btnDDplus_Click
    DisplayDatum=DateTime.Date(DateTime.DateParse(DisplayDatum)+DateTime.TicksPerDay*1)
    edtDate.Text=DisplayDatum
End Sub

Suddenly it seems stuck on 25-10-2020. I can decrease, but not increase. Starting on 26-10-2020 I can increase. Decrease before 25-10-2020, it still get stuck on 25-10-2020.

Does this somethingto do with winter/summer time?
I am in the Netherlands (+2).

Attached you will find a small example.

Is there somthing I do wrong? Can someone have look and tell me what to do?

Thanks,
BR, André

DonManfred · Oct 24, 2020

B4X:

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    Dim DisplayDatum As String
    Dim DiplayDateL As Long
    Private edtDate As EditText
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Activity.LoadLayout("Layout")
    DateTime.DateFormat="dd-MM-yyyy"
    DiplayDateL = DateTime.Now
    DisplayDatum=DateTime.Date(DateTime.Now)
    edtDate.Text=DisplayDatum
End Sub

Sub Activity_Resume

End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

Sub btnDDmin_Click
    DiplayDateL = DateTime.Add(DiplayDateL,0,0,-1)
    edtDate.Text=DateTime.Date(DiplayDateL)

End Sub

Sub btnDDplus_Click
    DiplayDateL = DateTime.Add(DiplayDateL,0,0,1)
    edtDate.Text=DateTime.Date(DiplayDateL)
End Sub

AHilberink · Oct 24, 2020

DonManfred said:

B4X:

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    Dim DisplayDatum As String
    Dim DiplayDateL As Long
    Private edtDate As EditText
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Activity.LoadLayout("Layout")
    DateTime.DateFormat="dd-MM-yyyy"
    DiplayDateL = DateTime.Now
    DisplayDatum=DateTime.Date(DateTime.Now)
    edtDate.Text=DisplayDatum
End Sub

Sub Activity_Resume

End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

Sub btnDDmin_Click
    DiplayDateL = DateTime.Add(DiplayDateL,0,0,-1)
    edtDate.Text=DateTime.Date(DiplayDateL)

End Sub

Sub btnDDplus_Click
    DiplayDateL = DateTime.Add(DiplayDateL,0,0,1)
    edtDate.Text=DateTime.Date(DiplayDateL)
End Sub

Thanks DonManfred. I changed it in my project and it works fine. This is a perfect solution.
Still wondering why my solution get stuck suddenly.

BR, André

Erel · Oct 25, 2020

Whenever you see date arithmetics code you should immediately know that the code is wrong. Dates are more complicated than it might seem.

You should use DateTime.Add and/or DateUtils.

Worth watching the date video tutorial: https://www.b4x.com/etp.html

AHilberink · Oct 25, 2020

Erel said:
Whenever you see date arithmetics code you should immediately know that the code is wrong. Dates are more complicated than it might seem.

You should use DateTime.Add and/or DateUtils.

Worth watching the date video tutorial: https://www.b4x.com/etp.html

Thanks for your reply and tutorial, Erel.

Android Question Date stuck on 25-10-2020.

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