I do not get messages from a server on my client

Question

I am trying to get my server made on vb.net to send messages to my client made on android. I have a client and server made on vb.net, I can send and receive messages (text) between them without problem. But when I try to make the client work the same on Android, I can not receive messages to the client (android), but if I could get it to send a message to the server (vb.net) .. They are stuck with this, and I do not understand how to continue

SERVER VB.NET

Imports System.Net.Sockets
Imports System.Text

Public Class Servidor
    Dim Tcp As TcpListener
    Dim th As New Threading.Thread(AddressOf Rutina)
    Dim ejecuto = False
    Private Sub Servidor_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        CheckForIllegalCrossThreadCalls = False
    End Sub
    Dim tcpservercliente As New TcpClient
    Public Function Rutina()
        Try
            Do
                If ejecuto = True Then
                    Exit Do
                End If
                If Tcp.Pending = True Then
                    tcpservercliente.Client = Tcp.AcceptSocket
                End If
                If tcpservercliente.Available > 0 Then
                    Dim databytes(1000) As Byte
                    Dim decode As New ASCIIEncoding
                    tcpservercliente.Client.Receive(databytes)
                    txtRecibido.Text += vbCrLf & "Cliente Android: " & decode.GetString(databytes)
                End If

            Loop
        Catch ex As System.InvalidOperationException
            MsgBox("Error: " & ex.Message)
        End Try




    End Function
    Private Sub btnStart_Click(sender As Object, e As EventArgs) Handles btnStart.Click
        Try
            Tcp = New TcpListener(System.Net.IPAddress.Parse("192.168.1.8"), 1371)
            Tcp.Start()
            th.Start()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

    End Sub

    Private Sub Servidor_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing
        th.Abort("Rutina")
        Application.Exit()
    End Sub

    Private Sub btnEnviar_Click(sender As Object, e As EventArgs) Handles btnEnviar.Click
        Try
            Dim decode As New ASCIIEncoding
            tcpservercliente.Client.Send(decode.GetBytes(txtMensajeEnviar.Text))
        Catch ex As System.Net.Sockets.SocketException
            MsgBox(ex.Message)
        End Try

    End Sub

CLIENT ANDROID

//CLASS RM 

public class RM extends AsyncTask<Void, Void, Void> {
    Socket socket;
    BufferedReader input;

    @Override
    protected Void doInBackground(Void... voids) {
        try {
            socket = new Socket("192.168.1.8",1371);
            InputStreamReader streamReader = new InputStreamReader(socket.getInputStream());
            input = new BufferedReader(streamReader);
            if(input.ready()){
                Log.i("AsyncTask", "Ready ");
            }else{
                Log.i("AsyncTask", "No Ready");
            }
            input.close();
            socket.close();
        }catch (IOException e){
            e.printStackTrace();
        }

        return null;
    }
}



//VOID MAIN ACTIVITY

RM mr = new RM();
        mr.execute();

The times I've tried to see that it returns, it's always empty. The message that is being sent from the server is not arriving

Sorry my bad english

==========================================

EDIT: This is the class I use to send messages from the client (android) to the server (vb.net)

package com.example.app_test_client;

import android.os.AsyncTask;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
public class MessageSender extends AsyncTask<String, Void, Void> {

    Socket socket;
    PrintWriter pw;
    @Override
    protected Void doInBackground(String... voids) {
        String mensaje_enviar = voids[0];
        try {
            socket = new Socket("192.168.1.8",1371);
            pw = new PrintWriter(socket.getOutputStream());
            pw.write(mensaje_enviar);
            pw.flush();
            pw.close();
            socket.close();
        }catch (IOException e){
            e.printStackTrace();
        }
        return null;
    }
}

CODE MAIN ACTIVITY (CLIENT ANDROID)

package com.example.app_test_client;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity{
    EditText mensaje_enviar;
    TextView mensaje_recibido;


    @Override

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mensaje_enviar = (EditText)findViewById(R.id.txtTexto);
        mensaje_recibido = (TextView)findViewById(R.id.lblMensaje);
    }

    public void enviar(View v){
        MessageSender MensajeRemitente = new MessageSender();
        MensajeRemitente.execute(mensaje_enviar.getText().toString());
    }
}

The void "enviar" I have it in the "onClick" button. All this to send messages from the client (android) to the server (vb.net) works for me.

Based on this class "MessageSender", I made another equal to receive messages on the client (android) but it has not worked

Answer 1

If you are trying to receive the message in the Android device, then you are missing reading the message itself with String messageReceived = input.readLine();. Your code would look like this:

...
socket = new Socket("192.168.1.8",1371);
InputStreamReader streamReader = new InputStreamReader(socket.getInputStream());
input = new BufferedReader(streamReader);
String messageReceived = input.readLine();
...

You will have the message sent from the server in messageReceived.

EDIT

Without getting into much details, when you read the data sent from the server, you need to know when the data sent "ends", and the easiest way you have with your current implementation is to print a "line end" (a vbCrLf character in VB) when you send the message. Thus, in your Sub btnEnviar_Click you need to add a vbCrLf as follows:

tcpservercliente.Client.Send(decode.GetBytes(txtMensajeEnviar.Text & vbCrLf))

Additional notes

1. When data is being read from the server the socket needs to know when the data ends. There are several ways of achieving this, but the easiest way is in your case is to read "a line ending" with String messageReceived = br.readLine();. If the server doesn't send any "line end" (as in your current implementation), it will keep waiting for it and hence it appears that the programs hungs. That is what is happening in your case when you note that you cannot do anything else after reading the message - it is just waiting for something that will never come.
2. It is not necessary that you check input.ready() when reading from the server. This will only be true when the data has been completely sent from the server, and there is a great chance that the data is still being sent when it is invoked.
3. If you want to know better how TCP sockets works, this SO question has good examples that you can try.