Android Question map to List and reverse

[FrankDev]

Probably a beginner problem. But I'm just not clear. When I write data into a map and then add it to a list Why do not I get it out the other way around?!? regards

 dim liste as list

 'put some data into a list

 Dim m As Map
 m.Initialize
 m.Put("id_user", From)
 m.Put("message",Message)
 m.Put("dtime", Zeit)
 liste.Add(m)


 
 'back from list to variable

 Dim m As Map = liste.Get(1)
 Dim msg As String = m.Get("message")

 

[udg]

Dim m AsMap = liste.Get(1)

Index should be zero since you add just one item

 

[FrankDev]

no.. the List contains hundred of items

is this realy the right syntax ?

 

[Derek Johnson]

Apart from the index to the list (which starts at zero) your code should work:

    Dim From,Message,Zeit As String
       
    Zeit=DateTime.Now
    From= "[email protected]"
    Message="This is a message.More ...    "

    Dim liste As List
     liste.Initialize
    'put some data into a list

    Dim m As Map
   
    m.Initialize
    m.Put("id_user",From)
    m.Put("message",Message)
    m.Put("dtime", Zeit)
    Log("Map: " & m)
    liste.Add(m)
   
    Log(liste)
    'back from list to variable
    Dim m As Map = liste.Get(0) 'List index starts at zero
    Log("Retrieved message"  & m)
    Dim msg As String = m.Get("message")
   
    Log("Msg: " & msg)

This gives:

Map: (MyMap) {id_user=[email protected], message=This is a message.More ... , dtime=1496741186827}
(ArrayList) [{id_user=[email protected], message=This is a message.More ... , dtime=1496741186827}]
Retrieved message(MyMap) {id_user=[email protected], message=This is a message.More ... , dtime=1496741186827}
Msg: This is a message.More ...
** Activity (main) Pause, UserClosed = false **
** Activity (main) Resume **

 

[ronell]

no.. the List contains hundred of items

is this realy the right syntax ?

liste.Add(m) '<-- 1 item

you just add 1 item on the list ..

 

[FrankDev]

hi Derek,

thanks for help.. i found MY mistake.
Thought that the list is already initialized. but it wasn't


A small mistake that cost me many hours.
I thought I had a wrong syntax

much thanks.

 

[Derek Johnson]

hi Derek,

thanks for help.. i found MY mistake.
Thought that the list is already initialized. but it wasn't


A small mistake that cost me many hours.
I thought I had a wrong syntax

much thanks.

I am surprised that you did not spot the lack of initialisation of the list object. If you were running in Debug mode, your first statement to add an item to the list would have shown up this error in the Debug log:

Error occurred on line: 65 (Main)
java.lang.RuntimeException: Object should first be initialized (List).
at anywheresoftware.b4a.AbsObjectWrapper.getObject(AbsObjectWrapper.java:50)
...etc

Anyway the moral is, always use debug mode to start with and always look at the log!

B4A is a great development environment and also has a great support community!

Good luck!

Derek

 

[FrankDev]

have never tried to use the debugmode because I always test on the smartphone.

I did not know that worked there.

Well that we talked about it

From mistakes one becomes wise

Frank

 

[Derek Johnson]

have never tried to use the debugmode because I always test on the smartphone.

I did not know that worked there.

Frank

You should read this introduction to debugging. https://www.b4x.com/android/forum/threads/b4a-bridge-a-new-way-to-connect-to-your-device.7978/

It's very easy to use either the B4a-Bridge App or to connect to the USB port on your phone (Once you have set your phone into Developer Mode.)

Derek

 

[Erel]

have never tried to use the debugmode because I always test on the smartphone.

We all do.