Android Socket Connection Test

Question

I'm trying to test if my Android App is connecting to a Rpi hot spot. I'm following this guide for the client code.

I want to have a toast message pop up depending on the state of socket.isConnected() when I hit a button. However, I think each time I try and implement it, I run into Network on the main thread problems. How could I change the following code to add a simple "if(true), send toast message" using the isConnected method in the onClick?

Thank you for any help!

package mrxhaleenterprise.sockettest;

import java.io.BufferedWriter;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

private Socket socket;

private static final int SERVERPORT = 39169;
private static final String SERVER_IP = "172.24.1.1";


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    new Thread(new ClientThread()).start();
}

public void onClick(View view) {

    try {

        EditText et = (EditText) findViewById(R.id.EditText01);
        String str = et.getText().toString();
        PrintWriter out = new PrintWriter(new BufferedWriter(
                new OutputStreamWriter(socket.getOutputStream())),
                true);
        out.println(str);
    } catch (UnknownHostException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

class ClientThread implements Runnable {

    @Override
    public void run() {

        try {
            InetAddress serverAddr = InetAddress.getByName(SERVER_IP);

            socket = new Socket(serverAddr, SERVERPORT);

        } catch (UnknownHostException e1) {
            e1.printStackTrace();
        } catch (IOException e1) {
            e1.printStackTrace();
        }

    }


}
}

can u share the error log? – Kaushal28 Feb 24 '17 at 05:50 — Kaushal28, Feb 24 '17 at 05:50

score 0 · Accepted Answer · answered Feb 24 '17 at 04:59

onClick is called on main Thread.So you are writing to socket(Network Operation) on main thread which is causing problem. Your below code should run on background thread.

PrintWriter out = new PrintWriter(new BufferedWriter(
                    new OutputStreamWriter(socket.getOutputStream())),
                    true);
            out.println(str);

user207421 · Answer 2 · 2017-02-24T09:00:26.387

I want to have a toast message pop up depending on the state of socket.isConnected() when I hit a button.

No you don't. Once you've constructed that Socket, it is connected, and that method won't magically start returning false if the connection goes down. You need to maintain your own state of the connection, depending on whether you've encountered an IOException or end of stream on it. More probably you don't want the button at all, you want to pop up an error dialogue when the disconnect happens.

Android Socket Connection Test

2 Answers2