Android Question "true","false",True, False How do they work?

[jtare]

I noticed that for some reason a boolean stored in a map that was read from a file no longer is a boolean but a string maybe?

I ran some tests where mymap.get("a") is False and mymap.get("b") is False and got this:

    Dim mymap As map = File.ReadMap(File.DirInternal,"mymap.txt")
    Log(Not(mymap.Get("a") Or mymap.Get("b"))) 'True
    Log("false"=False) 'True
    Log("false"=True) 'False
    Log("true"=True) 'True
    Log(mymap.Get("a") = False And mymap.Get("b") = False) 'False
    Log(mymap.Get("a") = False) 'False
    Log(mymap.Get("b") = False) 'False
    Log(mymap.Get("a") = "false" And mymap.Get("b") = "false") 'True
    Log(mymap.Get("a") = "false") 'True
    Log(mymap.Get("b") = "false") 'True

Both "a" and "b" value are set with a boolean variable, not string. Like this:

mymap.put("a",False)

I used to store the map in the keyvaluestore database and worked as expected. This weird behavior started when I moved to save it and read it from a file.

If the mymap is no longer holding a boolean but a string, shouldn't

log(mymap.Get("a") = False ) 'False

and

log("false"=False) 'True

Be the same? Both True? But instead I get False in the first one and True in the second one.

 

[DonManfred]

File. WriteMap (Dir As String, FileName As String, Map As Map)
Creates a new file and writes the given map. Each key value pair is written as a single line.
All values are converted to strings. <--- !!!

You should use B4ASerialisator or Randomaccessfile WriteB4XObject/ReadB4XObject

 

[jtare]

You should use B4ASerialisator or Randomaccessfile WriteB4XObject/ReadB4XObject

Thanks, I'll give it a try.

But still shoudn't

log(mymap.Get("a") = False ) 'False

and

log("false"=False) 'True

Be the same?

 

[DonManfred]

Cast the string to a Boolean and compare the two booleans.

 

[Computersmith64]

I use ReadMap & WriteMap a lot in my apps to save settings, so for Booleans I just use this utility function:

Private Sub CBool(sVal As String) As Boolean
    If sVal = "true" Then Return True Else Return False
End Sub

- Colin.

 

[jtare]

I use ReadMap & WriteMap a lot in my apps to save settings, so for Booleans I just use this utility function:

Private Sub CBool(sVal As String) As Boolean
    If sVal = "true" Then Return True Else Return False
End Sub

- Colin.

Thanks for the suggestion. I think I will go with this solution for now.

 

[RB Smissaert]

I use ReadMap & WriteMap a lot in my apps to save settings, so for Booleans I just use this utility function:

Private Sub CBool(sVal As String) As Boolean
    If sVal = "true" Then Return True Else Return False
End Sub

- Colin.

Not sure it is any better, but I would do:

Return sVal = "true"

or maybe better

Return sVal.ToLowerCase = "true"

RBS

 

[klaus]

Private Mapa, Mapb As Boolean
Mapa = MyMap.Get("a")
Mapb = MyMap.Get("b")

This works.
The problem is that MyMap.Get("a") is a String.
But, if you set MyMap.Get("a") to a Boolean variable, like Mapa = MyMap.Get("a"), B4A sets the value correctly.

 

[Cableguy]

Why not "simplify" things and set True=1 and false = 0, the IDE would then convert the string to the correct type, would it not?

 

[jtare]

Private Mapa, Mapb As Boolean
Mapa = MyMap.Get("a")
Mapb = MyMap.Get("b")

This works.
The problem is that MyMap.Get("a") is a String.
But, if you set MyMap.Get("a") to a Boolean variable, like Mapa = MyMap.Get("a"), B4A sets the value correctly.

Thanks.

Why not "simplify" things and set True=1 and false = 0, the IDE would then convert the string to the correct type, would it not?

Will have to check if "0"=0 is the same to mymap.get("a")=0, if not it kind of leave me in the same situation.