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Android tcp connection to computer

I am new to android.
I tried to build an application which sends a string from android mobile to a java client on my pc.
here is the server side:
public class Ser {
public static void main(String[] args) throws IOException {
ServerSocket ss = new ServerSocket(12345);
Socket s = ss.accept();
InputStream is = s.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
System.out.println("message received from server is :");
String ms = br.readLine();
System.out.println("" + ms);
}
}
and here is the client side:
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Socket s= null;
try {
s = new Socket("192.168.0.102",12345);
OutputStream os=s.getOutputStream();
PrintWriter pw=new PrintWriter(os);
pw.println("Hey!!! I am from client side ");
pw.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
}
but this is giving the following error:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ankitanand.udp/com.example.ankitanand.udp.MainActivity}: android.os.NetworkOnMainThreadException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2122)
at android.app.ActivityThread.access$600(ActivityThread.java:140)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1228)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4895)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.os.NetworkOnMainThreadException
at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1118)
at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
at libcore.io.IoBridge.connect(IoBridge.java:112)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.Socket.startupSocket(Socket.java:566)
at java.net.Socket.tryAllAddresses(Socket.java:127)
at java.net.Socket.<init>(Socket.java:177)
at java.net.Socket.<init>(Socket.java:149)
at com.example.ankitanand.udp.MainActivity.onCreate(MainActivity.java:30)
at android.app.Activity.performCreate(Activity.java:5163)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2061)
            
The ip of my pc is 192.168.0.102
Also i have used the following permission in the manifest file
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.INTERNET"/>

You can't do network stuff on the Main thread. Try using an AsyncTask
Take also a look on this page about Network on Main Thread Exeption.
With that your code will work.

Can't create handler inside thread that has not called Looper.prepare() android [duplicate]

This question already has answers here:
Can't create handler inside thread that has not called Looper.prepare()
(30 answers)
Closed 9 years ago.
The idea is when the TCP server receives a String message, if it is equal to "::turnOnBluetoothOn::". Will simply turn on the bluetooth on the device. By using the runCommand Method of the MessageHandler class. The problem is that I am getting the error Can't create handler inside thread that has not called Looper.prepare()
Here is my code:
import android.os.Looper;
import android.util.Log;
import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
public class TCPClient
{
private String serverMessage;
// <<<<<<< .mine
public static final String SERVERIP = "xx.xxx.xx.xx"; // your computer IP
public static final int SERVERPORT = 4444;
private OnMessageReceived mMessageListener = null;
private boolean mRun = false;
PrintWriter out;
BufferedReader in;
// Test for Thread
private volatile Looper mMyLooper;
/**
* Constructor of the class. OnMessagedReceived listens for the messages
* received from server
*/
public TCPClient(OnMessageReceived listener)
{
mMessageListener = listener;
}
/**
* Sends the message entered by client to the server
*
* #param message
* text entered by client
*/
public void sendMessage(String message)
{
if (out != null && !out.checkError())
{
out.println(message);
out.flush();
}
}
public void stopClient()
{
mRun = false;
}
public void run()
{
mRun = true;
try
{
// here you must put your computer's IP address.
InetAddress serverAddr = InetAddress.getByName(SERVERIP);
Log.e("TCP Client", "C: Connecting...");
// create a socket to make the connection with the server
Socket socket = new Socket(serverAddr, SERVERPORT);
try
{
// send the message to the server
out = new PrintWriter(new BufferedWriter(
new OutputStreamWriter(socket.getOutputStream())), true);
Log.e("TCP Client", "C: Sent.");
Log.e("TCP Client", "C: Done.");
// receive the message which the server sends back
in = new BufferedReader(new InputStreamReader(
socket.getInputStream()));
// in this while the client listens for the messages sent by the
// server
while (mRun)
{
serverMessage = in.readLine();
if (serverMessage != null && mMessageListener != null)
{
// call the method messageReceived from MyActivity class
mMessageListener.messageReceived(serverMessage);
System.out.println(serverMessage);
MessageHandler handler = new MessageHandler(serverMessage);
handler.runCommand();
}
serverMessage = null;
}
Log.e("RESPONSE FROM SERVER", "S: Received Message: '"
+ serverMessage + "'");
} catch (Exception e)
{
Log.e("TCP", "S: Error", e);
}
finally
{
// the socket must be closed. It is not possible to reconnect to
// this socket
// after it is closed, which means a new socket instance has to
// be created.
socket.close();
}
} catch (Exception e)
{
Log.e("TCP", "C: Error", e);
}
}
// Declare the interface. The method messageReceived(String message) will
// must be implemented in the MyActivity
// class at on asynckTask doInBackground
public interface OnMessageReceived
{
public void messageReceived(String message);
}
}
//AND THIS IS THE HANDLER CLASS
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.content.Intent;
public class MessageHandler extends Activity
{
private static final int REQUEST_ENABLE_BT = 0;
private static final int REQUEST_DISCOVERABLE_BT = 0;
final BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
private String Instruction;
MessageHandler(String Command)
{
Instruction = Command;
}
public void runCommand()
{
if (Instruction.equals("::turnBluetoothOn::"))
{
if (!mBluetoothAdapter.isEnabled())
{
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
return;
}
}
}
Update:
Here is the LogCat:
03-01 18:16:09.486: I/System.out(4752): ::turnBluetoothOn::
03-01 18:16:09.526: D/AndroidRuntime(4752): Shutting down VM
03-01 18:16:09.526: W/dalvikvm(4752): threadid=1: thread exiting with uncaught exception (group=0x4193a700)
03-01 18:16:09.546: E/AndroidRuntime(4752): FATAL EXCEPTION: main
03-01 18:16:09.546: E/AndroidRuntime(4752): java.lang.NullPointerException
03-01 18:16:09.546: E/AndroidRuntime(4752): at com.example.myactivity.MessageHandler.runCommand(MessageHandler.java:22)
03-01 18:16:09.546: E/AndroidRuntime(4752): at com.example.myactivity.TCPClient$1.run(TCPClient.java:108)
03-01 18:16:09.546: E/AndroidRuntime(4752): at android.os.Handler.handleCallback(Handler.java:730)
03-01 18:16:09.546: E/AndroidRuntime(4752): at android.os.Handler.dispatchMessage(Handler.java:92)
03-01 18:16:09.546: E/AndroidRuntime(4752): at android.os.Looper.loop(Looper.java:137)
03-01 18:16:09.546: E/AndroidRuntime(4752): at android.app.ActivityThread.main(ActivityThread.java:5103)
03-01 18:16:09.546: E/AndroidRuntime(4752): at java.lang.reflect.Method.invokeNative(Native Method)
03-01 18:16:09.546: E/AndroidRuntime(4752): at java.lang.reflect.Method.invoke(Method.java:525)
03-01 18:16:09.546: E/AndroidRuntime(4752): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
03-01 18:16:09.546: E/AndroidRuntime(4752): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-01 18:16:09.546: E/AndroidRuntime(4752): at dalvik.system.NativeStart.main(Native Method)

try this:
if (serverMessage != null && mMessageListener != null)
{
// call the method messageReceived from MyActivity class
mMessageListener.messageReceived(serverMessage);
new Handler(Looper.getMainLooper()).post(new Runnable() {
#Override
public void run() {
MessageHandler handler = new MessageHandler(serverMessage);
handler.runCommand();
}
});
}

According to the error information,you create handler inside a non-ui thread, you have declared mMyLooper,why not use it?
so my advice is that add this code:
mMyLooper = Looper.getMainLooper();
Looper.prepare();
before while (mRun).

Client socket times out when connecting to Server

I have a problem when I try to connect my physical device to my server using sockets. On the server side it does not seem to accept any connection while on the client side the socket times out. Any ideas why this is happening?
I provide my code below
Server Code:
public void run()
{
// TODO Auto-generated method stub
try{
gamePending = false;
pid = 0;
while(pid < 2){
System.out.println("Hello from run loop on game");
Socket tempSocket = server.accept();
System.out.println("Client connected at " + tempSocket.getLocalPort());
PrintWriter tempWriter = new PrintWriter(new BufferedWriter (new OutputStreamWriter(tempSocket.getOutputStream())),true);
tempWriter.println("" + pid);
players[pid] = new Client(tempSocket, pid, this);
players[pid].start();
gamePending = true;
if(pid == 0){sendMsg(pid, "waiting for other player");}
pid++;
}
}
catch(Exception e){
System.out.println("There has been an Error. Game will be Terminated.");
}
//Start new game for the next two players...
new Game();
}
Client Side:
public void run() {
// Connects to the Server....
try {
socket = new Socket("192.168.1.116", 9090);
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
in = new BufferedReader (new InputStreamReader(socket.getInputStream()));
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
out = new PrintWriter(socket.getOutputStream(),true);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
11-16 23:32:11.016: W/System.err(24213): java.net.ConnectException: failed to connect to /192.168.1.116 (port 9090): connect failed: ETIMEDOUT (Connection timed out)
11-16 23:32:11.016: W/System.err(24213): at libcore.io.IoBridge.connect(IoBridge.java:114)
11-16 23:32:11.016: W/System.err(24213): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
11-16 23:32:11.026: W/System.err(24213): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
11-16 23:32:11.026: W/System.err(24213): at java.net.Socket.connect(Socket.java:842)
11-16 23:32:11.026: W/System.err(24213): at vatos.locos.spheroknockout.Connection.run(Connection.java:22)
11-16 23:32:11.026: W/System.err(24213): at java.lang.Thread.run(Thread.java:841)
11-16 23:32:11.026: W/System.err(24213): Caused by: libcore.io.ErrnoException: connect failed: ETIMEDOUT (Connection timed out)
}

I can't be sure (because it does not appear in your code) but I think the server is not hosing on the same port (9090). That may be the main problem, but the server or client may also be blocked by a firewall (even if they run on the same machine).

Transfer file using Sockets Server/Client

Hi there I have 2 classes in order to push a file into an android device.
My Server CLass:
public class FileServer {
public static void main (String [] args ) throws IOException {
// create socket
ServerSocket servsock = new ServerSocket(13267);
while (true) {
System.out.println("Waiting...");
Socket sock = servsock.accept();
System.out.println("Accepted connection : " + sock);
// sendfile
File myFile = new File ("C:\\Users\\Petrica\\Desktop\\zzz.txt");
byte [] mybytearray = new byte [(int)myFile.length()];
FileInputStream fis = new FileInputStream(myFile);
BufferedInputStream bis = new BufferedInputStream(fis);
bis.read(mybytearray,0,mybytearray.length);
OutputStream os = sock.getOutputStream();
System.out.println("Sending...");
os.write(mybytearray,0,mybytearray.length);
os.flush();
sock.close();
}
}
}
And my Client Class:
public class TCPClient extends AsyncTask{
#Override
protected Object doInBackground(Object... params) {
int filesize=6022386; // filesize temporary hardcoded
long start = System.currentTimeMillis();
int bytesRead;
int current = 0;
// localhost for testing
Socket sock = null;
try {
sock = new Socket("127.0.0.1",13267);
} catch (UnknownHostException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
System.out.println("Connecting...");
// receive file
try {
byte [] mybytearray = new byte [filesize];
InputStream is = sock.getInputStream();
FileOutputStream fos = new FileOutputStream("/mnt/sdcard/zzz.txt");
BufferedOutputStream bos = new BufferedOutputStream(fos);
bytesRead = is.read(mybytearray,0,mybytearray.length);
current = bytesRead;
// thanks to A. Cádiz for the bug fix
do {
bytesRead =
is.read(mybytearray, current, (mybytearray.length-current));
if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);
bos.write(mybytearray, 0 , current);
bos.flush();
long end = System.currentTimeMillis();
System.out.println(end-start);
bos.close();
sock.close();
// TODO Auto-generated method stub
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
I get an error
09-09 15:52:39.261: E/AndroidRuntime(802): FATAL EXCEPTION: AsyncTask #1
09-09 15:52:39.261: E/AndroidRuntime(802): java.lang.RuntimeException: An error occured while executing doInBackground()
09-09 15:52:39.261: E/AndroidRuntime(802): at android.os.AsyncTask$3.done(AsyncTask.java:299)
09-09 15:52:39.261: E/AndroidRuntime(802): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
09-09 15:52:39.261: E/AndroidRuntime(802): at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
09-09 15:52:39.261: E/AndroidRuntime(802): at java.util.concurrent.FutureTask.run(FutureTask.java:239)
09-09 15:52:39.261: E/AndroidRuntime(802): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
09-09 15:52:39.261: E/AndroidRuntime(802): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
09-09 15:52:39.261: E/AndroidRuntime(802): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
09-09 15:52:39.261: E/AndroidRuntime(802): at java.lang.Thread.run(Thread.java:841)
09-09 15:52:39.261: E/AndroidRuntime(802): Caused by: java.lang.NullPointerException
09-09 15:52:39.261: E/AndroidRuntime(802): at com.aaaaaa.TCPClient.doInBackground(TCPClient.java:33)
09-09 15:52:39.261: E/AndroidRuntime(802): at com.aaaaaa.TCPClient.doInBackground(TCPClient.java:1)
09-09 15:52:39.261: E/AndroidRuntime(802): at android.os.AsyncTask$2.call(AsyncTask.java:287)
09-09 15:52:39.261: E/AndroidRuntime(802): at java.util.concurrent.FutureTask.run(FutureTask.java:234)
09-09 15:52:39.261: E/AndroidRuntime(802): ... 4 more
MainActivity:
public class MainActivity extends Activity {
TCPClient tcpc;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn = (Button) findViewById(R.id.send_button);
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
tcpc.execute();
}
});
}
}
Does anyone have an idea what should I do ??? In the future i would like to send 2 files :D .Thanks in advice .

You're really expected to be able to sort out your own NullPointerExceptions: at least I expect it, but when you get past that, your copy code is wrong. You are presently ignoring the count returned by read() and assuming it fills the buffer. It isn't guaranteed to do that. See the Javadoc.
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
Use this at both ends, with any buffer size > 0, typically 8192.

I don't think your Socket is connecting, but its hard to tell. IN your log output, it says NullPointerException caused by doInBackground() line 33. You should check line 33 in your editor, and better yet, show us in your post which line is 33. I kind of have a feeling that you call Socket sock = null;, then you try and instantiate a new Socket in a try block, but that fails, so sock still == null, then you call a method on sock, and boom, NPE.
If you are running the Server on a computer, and the AsyncTask on an Android device, you won't be able to try and connect to localhost (127.0.0.1). You should instead try to connect to the internal network ip of your computer (something like 192.168.1.XXX), assuming both devices are on WiFi. If you are running an android emulator, then 127.0.0.1 refers back to the emulated device, and all emulator sessions run on an emulated router that you will have to configure for port forwarding before you can refer to the development machine, see here-->http://developer.android.com/tools/devices/emulator.html#emulatornetworking
As Andras Balazs Lajtha says, it looks like TCPClient isn't ever initialized/created during onCreate(), it is only declared. Since your logcat output shows errors from TCPClient though, I assume you have that code actually running.
In general, when you post a log output that refers to problems with a specific line of code, you should start there, and when you post, tell us or show us which line that is. And of course, if line 33 isn't related to a null Socket object, then I haven't been much help at all :)

Application crashes while starting the new thread

I have a thread class when I start the thread and create the instance of thread class in the main class my app get crash. My main activity code for creating the thread is:
broadcast broadcastobject=new broadcast(messages);
broadcastobject.start();
My thread class is :
public class broadcast extends Thread {
private DatagramSocket socket;
String str;
private static final int TIMEOUT_MS = 10;
WifiManager mWifi;
EditText et;
DatagramPacket packet;
Button bt;
private static final int SERVERPORT = 11111;
private static final String SERVER_IP = "192.168.1.255";
public broadcast(String to) {
// TODO Auto-generated constructor stub
str = to;
}
/*
private InetAddress getBroadcastAddress() throws IOException {
DhcpInfo dhcp = mWifi.getDhcpInfo();
if (dhcp == null) {
//Log.d(TAG, "Could not get dhcp info");
return null;
}
int broadcast = (dhcp.ipAddress & dhcp.netmask) | ~dhcp.netmask;
byte[] quads = new byte[4];
for (int k = 0; k < 4; k++)
quads[k] = (byte) ((broadcast >> k * 8) & 0xFF);
return InetAddress.getByAddress(quads);
}
*/
#Override
public void run() {
try {
socket = new DatagramSocket(SERVERPORT);
socket.setBroadcast(true);
} catch (SocketException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
// socket.setSoTimeout(TIMEOUT_MS);
InetAddress serverAddr = null;
try {
serverAddr = InetAddress.getByName(SERVER_IP);
} catch (UnknownHostException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
packet = new DatagramPacket(str.getBytes(), str.length(),serverAddr,SERVERPORT);
try {
socket.send(packet);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
My log cat error is:
09-01 08:23:47.949: D/gralloc_goldfish(1720): Emulator without GPU emulation detected.
09-01 08:24:01.941: W/System.err(1720): java.net.SocketException: socket failed: EACCES (Permission denied)
09-01 08:24:01.941: W/System.err(1720): at libcore.io.IoBridge.socket(IoBridge.java:573)
09-01 08:24:01.979: W/System.err(1720): at java.net.PlainDatagramSocketImpl.create(PlainDatagramSocketImpl.java:91)
09-01 08:24:01.979: W/System.err(1720): at java.net.DatagramSocket.createSocket(DatagramSocket.java:131)
09-01 08:24:01.979: W/System.err(1720): at java.net.DatagramSocket.<init>(DatagramSocket.java:78)
09-01 08:24:01.989: W/System.err(1720): at soft.b.peopleassist.broadcast.run(broadcast.java:65)
09-01 08:24:01.989: W/System.err(1720): Caused by: libcore.io.ErrnoException: socket failed: EACCES (Permission denied)
09-01 08:24:01.999: W/System.err(1720): at libcore.io.Posix.socket(Native Method)
09-01 08:24:01.999: W/System.err(1720): at libcore.io.BlockGuardOs.socket(BlockGuardOs.java:169)
09-01 08:24:01.999: W/System.err(1720): at libcore.io.IoBridge.socket(IoBridge.java:558)
09-01 08:24:02.009: W/System.err(1720): ... 4 more
09-01 08:24:02.149: W/dalvikvm(1720): threadid=11: thread exiting with uncaught exception (group=0x409961f8)
09-01 08:24:02.149: E/AndroidRuntime(1720): FATAL EXCEPTION: Thread-114
09-01 08:24:02.149: E/AndroidRuntime(1720): java.lang.NullPointerException
09-01 08:24:02.149: E/AndroidRuntime(1720): at soft.b.peopleassist.broadcast.run(broadcast.java:92)
09-01 08:24:03.329: W/IInputConnectionWrapper(1720): showStatusIcon on inactive InputConnection

The thread is not the issue, the real issue is the EACCES (Permission denied), add this permission to your manifest file
<uses-permission android:name="android.permission.INTERNET"></uses-permission>