Android Question B4A, B4XTree and List

[mike1967]

Hello, wen compiling this code is ok on emulator, and on real device give me an error and the app crash:

Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Root.LoadLayout("menuattrezzature")
    Dim pathdb As String
  
    pathdb=DBUtils.CopyDBFromAssets("rant.sqlite")
  
    rant.Initialize(pathdb,"rant.sqlite",False)
  
    Dim archivi As List
    archivi.Initialize
    archivi=DBUtils.ExecuteMemoryTable(rant,"SELECT id,tipologia,attrezzatura,descrizione,inventario,matricola,ubicazione FROM IMPIANTI ORDER BY TIPOLOGIA",Null,0)
    Main.tipologia=""
    B4XTree1.ItemHeight=100dip
    B4XTree1.TextSize=10
    If archivi.size > 0 Then
        ToastMessageShow("sono qui",True)
        Dim record() As String
        For i= 0 To archivi.size-1
            record=archivi.Get(i)
            If Main.tipologia<>record(1) Then
                Main.tipologia=record(1)
                logo=Chr(0xf055)
                B4XTree1.AddBranch(Main.tipologia,Main.tipologia,"",logo,Colors.Red)
            End If
            B4XTree1.BranchTextColor=Colors.White
            index=record(0)
            B4XTree1.AddLeaf(record(2) & CRLF & record(3) & "- " &record(6) & CRLF & "Inventario: " & record(4) & CRLF & "Matricola: " & record(5),"",index,Main.tipologia)
            Log(record(0))
            Log(record(1))
            Log(record(2))
            Log(record(3))
            Log(record(4))
            Log(record(5))
            Log(record(6))
        Next
    End If
End Sub

Error:

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 it.regant.app.menuattrezzature._b4xpage_created(menuattrezzature.java:109)
    at it.regant.app.menuattrezzature.callSub(menuattrezzature.java:236)
    at anywheresoftware.b4a.keywords.Common.CallSub4(Common.java:1066)
    at anywheresoftware.b4a.keywords.Common.CallSubNew2(Common.java:1037)
    at it.regant.app.b4xpagesmanager._createpageifneeded(b4xpagesmanager.java:500)
    at it.regant.app.b4xpagesmanager._showpage(b4xpagesmanager.java:802)
    at it.regant.app.b4xpages._showpage(b4xpages.java:123)
    at it.regant.app.b4xmainpage._btnattrezzature_click(b4xmainpage.java:70)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:213)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:193)
    at anywheresoftware.b4a.objects.ViewWrapper$1.onClick(ViewWrapper.java:80)
    at android.view.View.performClick(View.java:7184)
    at android.view.View.performClickInternal(View.java:7157)
    at android.view.View.access$3500(View.java:821)
    at android.view.View$PerformClick.run(View.java:27660)
    at android.os.Handler.handleCallback(Handler.java:883)
    at android.os.Handler.dispatchMessage(Handler.java:100)
    at android.os.Looper.loop(Looper.java:224)
    at android.app.ActivityThread.main(ActivityThread.java:7561)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:995)

Seems that the "if then" Is not executed. (The table Is empty).Can help me ?
thanks in advance.

 

[Erel]

The problem is that you are putting Nulls inside an array of strings.
You can convert the null values to empty strings in the query:

archivi=DBUtils.ExecuteMemoryTable(rant,"SELECT IfNull(id, ''), IfNull(tipologia, ''), ...

 

[mike1967]

The problem is that you are putting Nulls inside an array of strings.
You can convert the null values to empty strings in the query:

archivi=DBUtils.ExecuteMemoryTable(rant,"SELECT IfNull(id, ''), IfNull(tipologia, ''), ...

Thanks for your time spend for me.