Hi. I am really a newbie here. Could you please help me understanding the example? i only knew about c++ so this is really confused me because it's so different.
the point is? in c++ u call all your needed procedure in main() but in b4a we can't do it like that? did all the sub will be executed in order?
B4X:
Sub Process_Globals //set the variable?
Type Message (Body As String, From As String)
End Sub
Sub Globals //set the variable?
Private txtHost As EditText
Private btnConnect As Button
Private rdbServer As RadioButton
Private rdbClient As RadioButton
Private txtName As EditText
End Sub
Sub Activity_Create(FirstTime As Boolean)
Activity.LoadLayout("1") //to load the layout
StateManager.RestoreState(Activity, "Main", 0) // what is this for?
End Sub
Sub Activity_Pause (UserClosed As Boolean)
StateManager.SaveState(Activity, "Main")
End Sub
Sub btnConnect_Click
If txtName.Text = "" Then
ToastMessageShow("Please enter your name.", True)
Return
End If
If rdbClient.Checked And txtHost.Text = "" Then
ToastMessageShow("Please enter the server ip address.", True)
Return
End If
Dim host As String = txtHost.Text
If rdbServer.Checked Then host = "127.0.0.1"
CallSub3(Starter, "ConnectTo", host, txtName.Text) // calling the starter?? does this code link the activity main and starter?
End Sub
B4X:
Sub Process_Globals
Private broker As MqttBroker
Private client As MqttClient
Private const port As Int = 51042
Private serializator As B4XSerializator
Public connected As Boolean
Private brokerStarted As Boolean
Private users As List
Public isServer As Boolean
Private currentName As String
End Sub
Sub Service_Create
broker.Initialize("", port) //to set up the broker? i dont want to use my phone as broker so should i omit this?
broker.DebugLog = False
users.Initialize
End Sub
Sub Service_Start (StartingIntent As Intent)
End Sub
Public Sub ConnectTo(Host As String, Name As String) //connecting the phone to host?
currentName = Name
isServer = Host = "127.0.0.1"
If isServer Then
If brokerStarted = False Then
broker.Start
brokerStarted = True
End If
users.Clear
Host = "127.0.0.1"
End If
If connected Then client.Close
client.Initialize("client", $"tcp://${Host}:${port}"$, "android" & Rnd(1, 10000000))
Dim mo As MqttConnectOptions
mo.Initialize("", "")
'this message will be sent if the client is disconnected unexpectedly.
mo.SetLastWill("all/disconnect", serializator.ConvertObjectToBytes(currentName), 0, False)
client.Connect2(mo)
End Sub
Private Sub client_Connected (Success As Boolean)
Log($"Connected: ${Success}"$)
If Success Then
connected = True
client.Subscribe("all/#", 0)
client.Publish2("all/connect", serializator.ConvertObjectToBytes(currentName), 0, False)
Else
ToastMessageShow("Error connecting: " & LastException, True)
End If
End Sub
Private Sub client_MessageArrived (Topic As String, Payload() As Byte)
Dim receivedObject As Object = serializator.ConvertBytesToObject(Payload)
If Topic = "all/connect" Or Topic = "all/disconnect" Then
'new client has connected or disconnected
Dim newUser As String = receivedObject
If isServer Then
Log($"${Topic}: ${newUser}"$)
Dim index As Int = users.IndexOf(newUser)
If Topic.EndsWith("connect") And index = -1 Then users.Add(newUser)
If Topic.EndsWith("disconnect") And index >= 0 Then users.RemoveAt(index)
client.Publish2("all/users", serializator.ConvertObjectToBytes(users), 0, False)
End If
Else if Topic = "all/users" Then
Dim newUsers As List = receivedObject
CallSubDelayed2(Chat, "NewUsers", newUsers) 'this will start the chat activity if it wasn't started yet.
Else
Dim m As Message = receivedObject
CallSub2(Chat, "NewMessage", m)
End If
End Sub
Public Sub SendMessage(Body As String)
If connected Then
client.Publish2("all", CreateMessage(Body), 0, False)
End If
End Sub
Public Sub Disconnect
If connected Then client.Close
End Sub
Private Sub CreateMessage(Body As String) As Byte()
Dim m As Message
m.Initialize
m.Body = Body
m.From = currentName
Return serializator.ConvertObjectToBytes(m)
End Sub
Private Sub client_Disconnected
connected = False
If IsPaused(Chat) = False Then
CallSub(Chat, "Disconnected")
End If
If isServer Then
broker.Stop
brokerStarted = False
End If
End Sub
Sub Application_Error (Error As Exception, StackTrace As String) As Boolean
Return True
End Sub
Sub Service_Destroy
End Subthe point is? in c++ u call all your needed procedure in main() but in b4a we can't do it like that? did all the sub will be executed in order?
