B4J Code Snippet IsEmptyString() function

My first tip for B4J.

IsEmptyString(); Returns True if x parameter is empty string or null

Public Sub IsEmptyString(x As String) As Boolean
      
  
    Dim bEmpty As Boolean
  

    bEmpty = x = Null      ' Because pure Null
  
 
    If Not( bEmpty ) Then
      
        bEmpty = x.CompareTo(Null) = 0   ' Because origin is field of table bbdd
       
        If Not( bEmpty ) Then         

            Dim cTrim As String = x.Trim
           
            bEmpty = cTrim.Length < 1

        End If

    End If  

    Return bEmpty

End Sub

 

[Erel]

Another implementation:

Public Sub IsEmptyString (x As String) As Boolean
 Return x = Null Or x.Trim.Length = 0
End Sub

Note that nulls are normally not expected.

 

[amminf]

No.
Your implementation fails when x origin is a data field table from database.

See at https://www.b4x.com/android/forum/threads/testing-string-value-to-null.64005/#post-413542

My IsEmptyString() check totally without exceptions if string is empty and in correct (and neccesary to avoid runtime errors) order.

 

[Erel]

Can you post an example where it fails?

 

[amminf]

Erel,

From Phil Griffiths. See at https://www.b4x.com/android/forum/threads/testing-string-value-to-null.64005/#post-413542

Dim VisitCountStr As String
Dim VisitCount As Int
VisitCountStr = Datamap.Get("visitcount")
If VisitCountStr <> Null Then
VisitCount = VisitCountStr 'let b4a take care of conversion between string and integer
Else
VisitCount = 0
End If

Regards

 

[Erel]

I see. The string is not really empty in that case. It holds the value "null".

You can use this code:

Public Sub IsEmptyString (x As String) As Boolean
   Return x = Null or x = "null" Or x.Trim.Length = 0
End Sub

 

[amminf]

I think that not so.

From data field is value null (without quotation marks, it is not a string), but is a special null, different to b4j null constant

From Phill Griffiths sample: "My database table contains an integer field which has a value of null"

 

[Erel]

Try to create an example...

 

[amminf]

Same issue, same problem. For me there is no problem. I just pretended to provide a safe isEmptyString () function.
https://www.b4x.com/android/forum/threads/nullpointerexception-on-a-string-comparaison.7869/#content