Android Question Gmap issue

H

Hirogens

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Longtime User
Hello I ask again for some help with GPS map tracking.
My app log all the GPS points like this (.txt)
When I want to trace all the point I use this:
B4X: 
If gmap.IsInitialized Then
        If File.ExternalWritable = False Then
            Msgbox("No rights to write"," ")
            Return
        Else
            shared = Starter.rp.GetSafeDirDefaultExternal("GPS_Location")
            Starter.rp.CheckAndRequest(Starter.rp.PERMISSION_READ_EXTERNAL_STORAGE)
            Starter.rp.CheckAndRequest(Starter.rp.PERMISSION_WRITE_EXTERNAL_STORAGE)
            Wait For Activity_PermissionResult(Permission As String, Result As Boolean)
            If Result Then SaveStringExample
        End If

        Dim pl As Polyline = gmap.AddPolyline

        pl.Points = File.ReadList(shared, "PositionsGPScycling.txt")
        pl.Color=Colors.Blue
        pl.ZIndex=3
    Else
        Log("Gmap not initialize llll")
    End If
The SaveStringExample check if the file already exist, and if it exist I try to parse this file to get the position.
I have an error with the parsing : " pl.Points = File.ReadList(shared, "PositionsGPScycling.txt")"
This is the error:
B4X: 
Map is not ready yet.
** Activity (page_statistique) Resume **
Map is not ready yet.
Isinit=> true
Gmap isinit:> true
File exist
Error occurred on line: 242 (page_statistique)
java.lang.ClassCastException: java.lang.String cannot be cast to com.google.android.gms.maps.model.LatLng
    at anywheresoftware.b4a.objects.MapFragmentWrapper$PolylineWrapper.setPoints(MapFragmentWrapper.java:496)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:710)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:339)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:249)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:139)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:166)
    at anywheresoftware.b4a.shell.DebugResumableSub$RemoteResumableSub.resume(DebugResumableSub.java:19)
    at anywheresoftware.b4a.BA.checkAndRunWaitForEvent(BA.java:240)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:132)
    at anywheresoftware.b4a.BA$2.run(BA.java:360)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6121)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)

How can I resolve this issue ? And it's enough to recreate my journey ?

Thanks =)
 

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  • PositionsGPScycling.txt
    9.5 KB · Views: 249
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H

Hirogens

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Longtime User
Erel said:
File.ReadList returns a list with string elements. You need to create a new list where each item in that list is a LatLng object.
Click to expand...
When you say list is a LatLng Object, I give this List to a Polyline object and just do this
B4X: 
pl.Points = File.ReadList(shared, "PositionsGPScycling.txt")
        pl.Color=Colors.Blue
        pl.ZIndex=3
Or I need to use something different ?

Thanks !
 
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H

Hirogens

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Longtime User
Erel said:
This cannot work. File.ReadList returns a List with string elements.
You need to create a new list with LatLng elements.
Click to expand...
So if I log all my Long/lat in a file every seconde. When I finish my journey I parse this file and recup' all my value in the Object, it can works ?
Sorry I don't realy know how work this Object :/
 
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marcick

marcick

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Something like this:

B4X: 
Dim Points as list

forEach ....
Dim ll As LatLng
ll.Initialize(lat, lon)
Points.Add(ll)
Next

pl.Points = Points

You need to scan your file, for each row retrieve the lat/lon values (float), create the ll objects and put it in Points list.
 
Last edited:
Upvote 0
H

Hirogens

Active Member
Licensed User
Longtime User
marcick said:
Something like this:

B4X: 
Dim Points as list

forEach ....
Dim ll As LatLng
ll.Initialize(lat, lon)
Points.Add(ll)
Next

pl.Points = Points

You need to scan your file, for each row retrieve the lat/lon values (float), create the ll objects and put it in Points list.
Click to expand...
Hello, I do this
B4X: 
Dim pl As Polyline = gmap.AddPolyline
        
        For Each k As Int In Starter.gmaps 'an array
            Dim ll As LatLng
            Dim lat_lng As String
            Dim lat As Double
            Dim lng As Double
            lat_lng = Starter.gmaps.GetValueAt(k)
            lat = lat_lng.SubString2(0, lat_lng.IndexOf(","))
            lng = lat_lng.SubString2(lat_lng.IndexOf(","), lat_lng.Length)
            ll.Initialize(lat, lng)       
        Next
        pl.Points = ll
        pl.Color=Colors.Blue
        pl.ZIndex=3
my gmaps value is a Map which contain a string with that : "Lattitude,longitude"
 
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marcick

marcick

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Longtime User
you're missing a list.

B4X: 
Dim pl As Polyline = gmap.AddPolyline
Dim lat_lng As String
Dim lat, lng As Double
Dim Points as list
For Each k As Int In Starter.gmaps 'an array
  lat_lng = Starter.gmaps.GetValueAt(k)
  lat = lat_lng.SubString2(0, lat_lng.IndexOf(","))
  lng = lat_lng.SubString2(lat_lng.IndexOf(","), lat_lng.Length)
  Dim ll As LatLng
  ll.Initialize(lat, lng)      
  Points.add (ll)
Next
pl.Points = Points
pl.Color=Colors.Blue
pl.ZIndex=3
 
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H

Hirogens

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Licensed User
Longtime User
marcick said:
you're missing a list.

B4X: 
Dim pl As Polyline = gmap.AddPolyline
Dim lat_lng As String
Dim lat, lng As Double
Dim Points as list
For Each k As Int In Starter.gmaps 'an array
  lat_lng = Starter.gmaps.GetValueAt(k)
  lat = lat_lng.SubString2(0, lat_lng.IndexOf(","))
  lng = lat_lng.SubString2(lat_lng.IndexOf(","), lat_lng.Length)
  Dim ll As LatLng
  ll.Initialize(lat, lng)    
  Points.add (ll)
Next
pl.Points = Points
pl.Color=Colors.Blue
pl.ZIndex=3
Click to expand...
Well I do want you said but I have this
B4X: 
Error occurred on line: 251 (page_statistique)
java.lang.RuntimeException: Object should first be initialized (List).
    at anywheresoftware.b4a.AbsObjectWrapper.getObject(AbsObjectWrapper.java:50)
    at anywheresoftware.b4a.objects.collections.List.Add(List.java:76)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runVoidMethod(Shell.java:755)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:345)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:249)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:139)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:166)
    at anywheresoftware.b4a.shell.DebugResumableSub$RemoteResumableSub.resume(DebugResumableSub.java:19)
    at anywheresoftware.b4a.BA.checkAndRunWaitForEvent(BA.java:240)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:132)
    at anywheresoftware.b4a.BA$2.run(BA.java:360)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6121)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)

Edit: My bad forgot to initialize Points;)
 
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H

Hirogens

Active Member
Licensed User
Longtime User
marcick said:
Try to log your latlng points, maybe you’re not extracting them correctly
Click to expand...
So when I finish my activity I use File.WriteMap to create a .txt file with the values (pb: I would like to stock in Key order like 0,1,2,3,etc but actually it's stock randomly :/)
My lat/long are like this
 

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  • issue.txt
    1.9 KB · Views: 253
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marcick

marcick

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That is.
I don’t know where do you live but it’s evident in the file that the coordinates are not correct.
Double check it, especially just before creating the latlng object.
 
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H

Hirogens

Active Member
Licensed User
Longtime User
marcick said:
That is.
I don’t know where do you live but it’s evident in the file that the coordinates are not correct.
Double check it, especially just before creating the latlng object.
Click to expand...
I live in France, but when I get the postion I do this
B4X: 
If gmaps.IsInitialized Then
        gmaps.Put(Key, Round(Location1.Latitude*11930464.7111) & "," & Round(Location1.Longitude*11930464.7111))
        Key = Key + 1
        Log("+1")
    End If

Edit: Now I have that but no map design: Lat: 49 Longi: 6
 
Last edited:
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marcick

marcick

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Longtime User
????
I don’t understand what that calculation is for.
Just store latitude and longitude as they’re.
You can use Format to store them as string with fixed number of digit eventually
 
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H

Hirogens

Active Member
Licensed User
Longtime User
marcick said:
????
I don’t understand what that calculation is for.
Just store latitude and longitude as they’re.
You can use Format to store them as string with fixed number of digit eventually
Click to expand...
Now I have something better but still no map :/
(Lat 49 long:6) Values rounds
 
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H

Hirogens

Active Member
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Longtime User
No Point on the map :/ I check if everything are initialize, I put a break point on pl.Points = Points I pass here but nothing appear on my map :/
 
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