Android Question [Solved] read the events from a specific google calendar - error

[AnandGupta]

I need to read the events from a specific google calendar (I have a few on my phone) and list them date wise.

Searching our Forum I found Don's very good library and explanation,

Working with Calendars using ContentResolver (Query, Insert, Update, Delete)

Hello, i´m playing around with the Calendars on my Device and want to Query them. I found out how it works using ContentResolver querying the ContentProvider available in Android. You can find it documented here. I started using java code and a java-librarywrapper for this but then i realized...

www.b4x.com

I assume this is the way to go in current version.

I got error in B4XPages, may be I made some mistake somewhere, so I tried Activity logic, as the explanation is based on it.
I copy pasted the codes as explained but still got error.

Sub Activity_Create(FirstTime As Boolean)
    canAccessCal = False
    Activity.LoadLayout("Layout")

    Starter.rp.CheckAndRequest("android.permission.READ_CALENDAR")
    wait for Activity_PermissionResult (Permission As String, Result As Boolean)
    If Result = False Then
        Log("NO Permission READ Calendar")
    Else
        Starter.rp.CheckAndRequest("android.permission.WRITE_CALENDAR")
        wait for Activity_PermissionResult (Permission As String, Result As Boolean)
        If Result Then
            canAccessCal = True
            cr.Initialize("CR")
        End If
    End If
    If canAccessCal Then
        ' We are working from here now...
        Log("can read write calendar")
        
        Dim projection() As String = Array As String(ccon.ID,ccon.NAME,ccon.CALENDAR_DISPLAY_NAME,ccon.ACCOUNT_NAME,ccon.ACCOUNT_TYPE,ccon.OWNER_ACCOUNT)
        
        cr.QueryAsync(ccon.CONTENT_URI,projection, ccon.VISIBLE&"=1",Null,ccon.ID&" ASC")
        wait for CR_QueryCompleted(Success As Boolean, Crsr As Cursor)
        Log($"QueryCompleted(${Success})"$)
        If Crsr.IsInitialized Then
            If Crsr.RowCount > 0 Then
                Dim Cursor As Cursor
                Cursor = Crsr
                For i = 0 To Cursor.RowCount - 1
                    Cursor.Position = i
                    'calcon.ACCOUNT_TYPE,calcon.OWNER_ACCOUNT)
                    Log($"CR --------------------------------------"$)
                    Log(Cursor.GetString(ccon.ID)) ' You can use the constants you used for the projection. But remember: only the ones you defined in the projection are available in the Result.
                    Log(Cursor.GetString(ccon.NAME))
                    Log(Cursor.GetString(ccon.CALENDAR_DISPLAY_NAME))
                    Log(Cursor.GetString(ccon.ACCOUNT_NAME))
                    Log(Cursor.GetString(ccon.ACCOUNT_TYPE))
                    Log(Cursor.GetString(ccon.OWNER_ACCOUNT))
                Next
                Cursor.Close
            Else
                ' No rows
            End If
        Else
            '
        End If
    End If
End Sub

Error log

Logger connected to:  Xiaomi Redmi 4
--------- beginning of main
*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
** Activity (main) Resume **
can read write calendar
QueryCompleted(true)
CR --------------------------------------
1
main$ResumableSub_Activity_Createresume (java line: 556)
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
    at anywheresoftware.b4a.BA.addLogPrefix(BA.java:604)
    at anywheresoftware.b4a.keywords.Common.LogImpl(Common.java:191)
    at b4a.GCalenadar.main$ResumableSub_Activity_Create.resume(main.java:556)
    at anywheresoftware.b4a.BA.checkAndRunWaitForEvent(BA.java:267)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:207)
    at anywheresoftware.b4a.BA$2.run(BA.java:387)
    at android.os.Handler.handleCallback(Handler.java:754)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:163)
    at android.app.ActivityThread.main(ActivityThread.java:6238)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:933)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)

I think I need to change some string value but do not know which one.
Please help.

Regards,

Anand

 

[Erel]

The error happens because you are trying to log a Null string.

 

[AnandGupta]

The error happens because you are trying to log a Null string.

Ok.

Checked in Android 5 phone, gives proper log as expected and no error.

Checked in Android 7 and 9 phone, gives same error.
So there must be something more to set like permission or manifest etc. for higher Android versions. Since the original code of Don is old, so I could not get from there any hint or may be I am missing something.

Any guide on it or search result will help. Attached the project zip. It is just showing calendar names, if not error.

Regards,

Anand

 

[Erel]

One of the Cursor.GetString calls returns a Null value and it causes an error. This issue will not happen in the next update of B4A.

Change the Log lines like this:

Log("id: " & Cursor.GetString(ccon.ID))

 

[AnandGupta]

One of the Cursor.GetString calls returns a Null value and it causes an error. This issue will not happen in the next update of B4A.

Change the Log lines like this:

Log("id: " & Cursor.GetString(ccon.ID))

Sorry for late reply, was busy with bread and butter.

Yes this works perfectly and shows all my calendar names. Thank you.

Regards,

Anand