inputStream null delay Kotlin

Question

Hi there I'm writing a client app in android studio

this is my client class:


class Client : Socket()
{

    init {
        recvMessage()
    }

    companion object
    {
        var receivedMessage :ByteArray = ByteArray(1024)
    }


    fun sendMessage(data: ByteArray )
    {
        if(isConnected)
            Thread {
                val dataOutputStream = DataOutputStream(this.outputStream)
                dataOutputStream.write(data)
            }.start()
    }



    private fun recvMessage() = Thread{
        while(true)
        {
            if (isConnected) {
                inputStream.read(receivedMessage)
            }
        }
    }.start()

    fun getMessage():ByteArray
    {
        return receivedMessage;
    }

}

To use this client I have MyApplication class as shown here

In the app startup the client get configured (connects to server)

then I move to login activity there I send a login request to the server and get an answer this is the login button function

fun login(view: View)
{
        val username = findViewById<EditText>(R.id.username).text.toString()
        val password = findViewById<EditText>(R.id.password).text.toString()

        (this.application as MyApplication).client.sendMessage(PacketFactory.loginRequest(username, password))
        val serverResponse = (this.application as MyApplication).client.getMessage()
        val buf : ByteBuffer = ByteBuffer.wrap(serverResponse)

        println()
        println("got:" + Message.getRootAsMessage(buf).data)
        println()


}

The problem is that at the first click I get null then the msg I needed before (a click before)

Any help for those more experienced would be most appreciated. I'm at the end of my skills here... need some guidance, please!

Of course. You start a thread to send and receive a message. But before the thread has send or received a message you already try to read a received message. There is nothing received yet. That is normal uding threads. — blackapps, Jun 03 '20 at 11:44
Your sendMessage function also tries to receive a message. Quite confusing name. — blackapps, Jun 03 '20 at 11:45

score 0 · Accepted Answer · answered Jun 03 '20 at 13:08

fixed: I added messages stack

package com.trivia_app
import java.io.DataOutputStream
import java.net.Socket
import java.util.*

class Client : Socket()
{

    init {
        recvMessage()
    }

    companion object
    {
        var pendingMessages : Stack<ByteArray> = Stack()
    }


    fun sendMessage(data: ByteArray )
    {
        if(isConnected)
            Thread {
                val dataOutputStream = DataOutputStream(this.outputStream)
                dataOutputStream.write(data)
            }.start()
    }



    private fun recvMessage() = Thread{
        val message = ByteArray(1024)
        while(true)
            if (isConnected)
                if (inputStream.read(message) > 0)
                    pendingMessages.push(message)
    }.start()

    fun getMessage():ByteArray
    {
        while (pendingMessages.empty());
        return pendingMessages.pop()
    }

}

inputStream null delay Kotlin

1 Answers1