Android Question Checking an object

[clooney48]

Hi!

How can I check if an object is empty (Uri)?? I am not able to do it. I tried it with this code but the if query doesn´t work and the "Cursor.Position = 0" returns an error for the cases that I pressed the return button and the Uri variable is empty.

Dim Uri As Object
  Uri = r.RunStaticMethod("android.net.Uri", "parse", _
      Array As Object(UriString), _
      Array As String("java.lang.String"))

If Uri <> Null Then '<< THIS DOESN´T WORK 
  Cursor.Position = 0
  Dim res As String
  res = Cursor.GetString("_data")
  Cursor.Close
  Return res
  End If

 

[Erel]

It doesn't work because Uri is not null. It cannot be null based in your code.

Note that you do not need to use reflection. You can instead use ContentResolver library.

 

[clooney48]

Yes I know.
Therefore i put the if statement afterwards to stop executing the rest of the procedure but the if statement doesn´t work and therefore I get an error.

 

[Erel]

In which way doesn't it work? Uri cannot be Null at that point. It will never be (based on the implementation of android.net.Uri.parse).

 

[clooney48]

When I press the Back button on the phone after the process started I get an error because Uri = ""

 

[Erel]

So you need to check:

If UriString <> "" Then

 

[clooney48]

So you need to check:

If UriString <> "" Then

Thanks, I will check it this evening ;-)

 

[clooney48]

Thanks, I will check it this evening ;-)

Great, this works fine. Thank you very much!

 

[eps]

When I press the Back button on the phone after the process started I get an error because Uri = ""

That is not the same as Null. Null means no value, an empty string assigned to a variable then means that it isn't Null, as it has a value, even if that string doesn't have a length.

So null means no value and hasn't had a value.

assigning "" to a string means it hasn't got a length, but it's not null either.

HTH

 

[clooney48]

That is not the same as Null. Null means no value, an empty string assigned to a variable then means that it isn't Null, as it has a value, even if that string doesn't have a length.

So null means no value and hasn't had a value.

assigning "" to a string means it hasn't got a length, but it's not null either.

HTH

Thanks for the detailed explanation! Now it is very clear!