Android Question Playing a MP3 file from External Storage

Sub Class_Globals
    Private Root As B4XView
    Private xui As XUI
    Private storage As ExternalStorage
    Private player As SimpleExoPlayer
End Sub

Public Sub Initialize
    
End Sub

Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Root.LoadLayout("MainPage")
    storage.Initialize(Me, "storage")
    player.Initialize("exoplayer")
End Sub


Sub Button1_Click
    storage.SelectDir(True)
    Wait For Storage_ExternalFolderAvailable
    Dim music As ExternalFile = storage.FindFile(storage.Root, "2.mp3")
    If music.IsInitialized Then
        Dim uri As String = music.Native.RunMethodJO("getUri", Null).RunMethod("toString", Null)
        Log(uri)
        player.Prepare(player.CreateUriSource(uri))
    End If
End Sub

Sub ExoPlayer_Ready
    Log("ready")
    player.Play
End Sub

Sub ExoPlayer_Error (Message As String)
    Log("error: " & Message)
End Sub