I'm working on a test project, something like a basic chat program using wi-fi connection.
I'm creating sockets to connect two different devices, but my problem is that when I send the first message, it's showing in the other device. But if I try to send again, I can see in the logs from the first one, that the message is sent, but it never shows up in the second device.
I've tried to implement the reading of the received data in another thread..or in Async Task, but the problem is still there. Here are both ways of my implementation :
Single Thread :
public void listenForSocket(){
thread = new Thread(new Runnable() {
public void run() {
Log.e("READDATAFROMSOCKET","READDATAFROMSOCKET");
try {
// sets the service running state to true so we can get it's state from other classes and functions.
serverSocket = new ServerSocket(DNSUtils.port);
client = serverSocket.accept();
client.setKeepAlive(true);
InputStream is = client.getInputStream();
Log.d("","is Size : "+is.available());
BufferedReader in = new BufferedReader(new InputStreamReader(is));
int readed = in.read();
Log.d("","readed bytes : "+readed);
String line = "";
while ((line = in.readLine()) != null) {
Log.i("","line : "+line);
changeText(line);
}
//client.close();
//serverSocket.close();
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
});
thread.start();
}
And here is AsyncTask :
class ServerTask extends AsyncTask<Void, Void, Void>{
private String line = "";
#Override
protected Void doInBackground(Void... params) {
try {
Log.e("ASYNCTASK","ASYNCTASK");
// sets the service running state to true so we can get it's state from other classes and functions.
serverSocket = new ServerSocket(DNSUtils.port);
client = serverSocket.accept();
client.setKeepAlive(true);
InputStream is = client.getInputStream();
Log.d("","is Size : "+is.available());
BufferedReader in = new BufferedReader(new InputStreamReader(is));
int readed = in.read();
Log.d("","readed bytes : "+readed);
while ((line = in.readLine()) != null) {
Log.i("","line : "+line);
}
//client.close();
//serverSocket.close();
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
changeText(line);
}
}
changeText(String); -
private void changeText(final String line) {
runOnUiThread(new Runnable() {
#Override
public void run() {
LinearLayout.LayoutParams params = new LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
params.gravity = Gravity.RIGHT;
TextView sendMsg = new TextView(MainActivity.this);
sendMsg.setText(DNSUtils.clientName+" : "+line);
sendMsg.setTextColor(Color.DKGRAY);
sendMsg.setTextSize(18);
layout.addView(sendMsg, params);
}
});
}
Any ideas how to fix this issue?
And another problem is that when I am reading the received data, the first letter of the sent string never shows. It always starts from the second letter.
Thanks in advance.
If i were you i will try to implement serverSocket = new ServerSocket(DNSUtils.port); only once with new; not in every thread.
Related
I want to receive and send data with a web server but the code does not work
What do I do for this code to work?
Note this code inside onCreate
try {
URL url = new URL("http://myweb.com/");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
InputStream Stream = connection.getInputStream();
InputStreamReader reader = new InputStreamReader(Stream);
BufferedReader b = new BufferedReader(reader);
StringBuilder s = new StringBuilder();
String str ="";
while ((str = b.readLine())!=null) {
s.append(str);
}
String data = s.toString();
TextView myText = (TextView) findViewById(R.id.Text);
myText.setText(data);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
Make sure that you do network-related tasks on a separate thread in Android. Also, check that you have the INTERNET permission set.
If you want to then update the UI from another thread, you have to use
runOnUiThread (new Runnable () {
public void run() {
//update ui in here
}
}
All your code runs in Main thread which should be always used for setting up the UI and to listen for UI events such as on click listeners.
Network calls are not allowed on this thread as they might take long time. Use AsyncTask API of android which is designed for running code in separate thread.
Create a class like one below for all GET request tasks.
public class DownloadTask extends AsyncTask<String, Void, Integer> {
private String TAG = "InDownloadTask";
private DownloadCallback callback;
private String data;
public DownloadTask(DownloadCallback cb){
callback = cb;
}
#Override
protected Integer doInBackground(String... params) {
Integer result = 0;
HttpURLConnection urlConnection;
try {
URL url = new URL(params[0]);
urlConnection = (HttpURLConnection) url.openConnection();
int statusCode = urlConnection.getResponseCode();
if (statusCode == 200) {
BufferedReader r = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder response = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
response.append(line);
}
data = response.toString();
result = 1;
} else {
result = 0;
}
} catch (Exception e) {
Log.d(TAG, e.getLocalizedMessage());
}
return result;
}
#Override
protected void onPostExecute(Integer integer) {
super.onPostExecute(integer);
callback.onFinishDownload(data, integer);
}
}
Create a callback interface that we use for the above class.
public interface DownloadCallback {
public void onFinishDownload(String data, Integer result);
}
Now from your activity onCreate
String url = "http://myweb.com/";
new DownloadTask(new DownloadCallback() {
public void onFinishDownload(String data, Integer result) {
if(result == 1)
myText.setText(data);
else
myText.setText("Error");
}
}).execute(url);
If you have many network related operations, use a Network library such as Volley which will take care of this.
My code is designed to read a .txt file from a URL, and then display the text inside my textview. the problem is, I am using this code in a class. and getting this error- "cannot resolve method runOnUiThread". How do I fix this??
public class mydownloaderclass {
// this method is called from MainActivity
public static void checkForUpdates(Context context) {
new Thread() {
#Override
public void run() {
String path ="http://host.com/info.txt";
URL u = null;
try {
u = new URL(path);
HttpURLConnection c = (HttpURLConnection) u.openConnection();
c.setRequestMethod("GET");
c.connect();
InputStream in = c.getInputStream();
final ByteArrayOutputStream bo = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
in.read(buffer); // Read from Buffer.
bo.write(buffer); // Write Into Buffer.
runOnUiThread(new Runnable() {
#Override
public void run() {
TextView text = (TextView) findViewById(R.id.TextView1);
text.setText(bo.toString());
try {
bo.close();
} catch (IOException e) {
e.printStackTrace();
}
}
});
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}.start();
}
}
I tried using asynctask
public class readtextfile extends AsyncTask<String, Integer, String> {
#Override
protected String doInBackground(String... params) {
String result = "";
try {
URL url = new URL("https://www.dropbox.com/myfile.txt");
BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
String line = null;
while ((line = in.readLine()) != null) {
//get lines
result += line;
}
in.close();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return result;
}
#Override
protected void onPostExecute(String result) {
Toast.makeText(context, result, Toast.LENGTH_LONG).show();
}
}
Create a Handler instead to execute statements on Main Thread like this
Handler handler = new Handler(Looper.getMainLooper());
handler.post(new Runnable() {
#Override
public void run() {
//Write your RUN on UI Runnable code here
TextView text = (TextView) findViewById(R.id.TextView1);
text.setText(bo.toString());
try {
bo.close();
} catch (IOException e) {
e.printStackTrace();
} });
Try passing a view context. It can be the activity context where the text view is defined.
The runOnUiThread runs on the main looper so it required a UI context.
For that You can define a member field in the class where the Thread is defined and set it in the constructor. Or if the thread is in the activity itself. then simply set the context field in OnCreate and use it in the thread.
Hope this helps. :)
Let me know if this fixes it.
I would suggest you to use AsyncTask, android makes this class specially for doing some task on a working thread(doInBackgroung()) and then update UI in onPostExecute() method.
I'm asking for a little help here..
I made a Android app in order to get messages from a server. The app just have to show the server's messages and nothing else.
the thing is nothing is shown in the UI, all the messages are shown when I disconnect the server.
It's frustrating because the app get the data's, just don't show them before the disconnection of the server.
Here is my code :
public class SlimpleTextClientActivity extends Activity {
private TextView textView;
private Socket client;
private PrintWriter printwriter;
private BufferedReader bufferedReader;
//Following is the IP address of the chat server. You can change this IP address according to your configuration.
// I have localhost IP address for Android emulator.
private String CHAT_SERVER_IP = "192.168.2.2";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_slimple_text_client);
textView = (TextView) findViewById(R.id.textView1);
ChatOperator chatOperator = new ChatOperator();
chatOperator.execute();
}
/**
* This AsyncTask create the connection with the server and initialize the
* chat senders and receivers.
*/
private class ChatOperator extends AsyncTask<Void, Void, Void> {
#Override
protected Void doInBackground(Void... arg0) {
try {
client = new Socket(CHAT_SERVER_IP, 6666); // Creating the server socket.
if (client != null) {
printwriter = new PrintWriter(client.getOutputStream(), true);
InputStreamReader inputStreamReader = new InputStreamReader(client.getInputStream());
bufferedReader = new BufferedReader(inputStreamReader);
} else {
System.out.println("Server has not bean started on port 4444.");
}
} catch (UnknownHostException e) {
System.out.println("Faild to connect server " + CHAT_SERVER_IP);
e.printStackTrace();
} catch (IOException e) {
System.out.println("Faild to connect server " + CHAT_SERVER_IP);
e.printStackTrace();
}
return null;
}
/**
* Following method is executed at the end of doInBackground method.
*/
#Override
protected void onPostExecute(Void result) {
Receiver receiver = new Receiver(); // Initialize chat receiver AsyncTask.
receiver.execute();
}
}
/**
* This AsyncTask continuously reads the input buffer and show the chat
* message if a message is availble.
*/
private class Receiver extends AsyncTask<Void, Void, Void> {
private String message;
#Override
protected Void doInBackground(Void... params) {
while (true) {
try {
if (bufferedReader.ready()) {
message = bufferedReader.readLine();
publishProgress(null);
}
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
Thread.sleep(500);
} catch (InterruptedException ie) {
}
}
}
#Override
protected void onProgressUpdate(Void... values) {
textView.append( message + "\n");
}
}
}
Hope that someone have an idea because here... I don't x)
Simon !
EDIT :
So... I went to java to test my code (simplification with the System.out.println)
Here is my code :
public class MainClass {
public static void main(String[] args) throws Exception {
final Socket client;
InputStream is = null;
InputStreamReader isr = null;
BufferedReader br = null;
try{
client = new Socket("192.168.2.2", 6666);
InputStreamReader inputStreamReader = new InputStreamReader(client.getInputStream());
// create new buffered reader
br = new BufferedReader(inputStreamReader);
int value=0;
String monChar = null;
String maChaine = null;
//System.out.println(maChaine);
// reads to the end of the stream
while((value = br.read()) != -1)
{
// converts int to character
char c = (char) value;
maChaine = maChaine + c;
}
}catch(Exception e){
e.printStackTrace();
}finally{
// releases resources associated with the streams
if(is!=null)
is.close();
if(isr!=null)
isr.close();
if(br!=null)
br.close();
}
}
}
The thing is that I can't reach maChaine.
This does the same thing that before : I only can reach my String when the server is disconected.
If I put a "System.out.println(maChaine);" in my While it will print something at each rows and if I put it after it will only do something if the server is disconected.
Is there a way to ping a host (standard Android or via NDK implementation), and get detailed info on the response? (time, ttl, lost packages, etc..)
I was thinking of some open source app that has this feature but can't find any...
Thanks
Afaik, sending ICMP ECHO requests needs root (i.e. the app that does it needs to be setuid) - and that's not currently possible in "stock" Android (hell, even the InetAddress#isReachable() method in Android is a joke that doesn't work according to spec).
A very basic example using /usr/bin/ping & Process - reading the ping results, using an AsyncTask:
public class PingActivity extends Activity {
PingTask mTask;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
#Override
protected void onResume() {
super.onResume();
mTask = new PingTask();
// Ping the host "android.com"
mTask.execute("android.com");
}
#Override
protected void onPause() {
super.onPause();
mTask.stop();
}
class PingTask extends AsyncTask<String, Void, Void> {
PipedOutputStream mPOut;
PipedInputStream mPIn;
LineNumberReader mReader;
Process mProcess;
TextView mText = (TextView) findViewById(R.id.text);
#Override
protected void onPreExecute() {
mPOut = new PipedOutputStream();
try {
mPIn = new PipedInputStream(mPOut);
mReader = new LineNumberReader(new InputStreamReader(mPIn));
} catch (IOException e) {
cancel(true);
}
}
public void stop() {
Process p = mProcess;
if (p != null) {
p.destroy();
}
cancel(true);
}
#Override
protected Void doInBackground(String... params) {
try {
mProcess = new ProcessBuilder()
.command("/system/bin/ping", params[0])
.redirectErrorStream(true)
.start();
try {
InputStream in = mProcess.getInputStream();
OutputStream out = mProcess.getOutputStream();
byte[] buffer = new byte[1024];
int count;
// in -> buffer -> mPOut -> mReader -> 1 line of ping information to parse
while ((count = in.read(buffer)) != -1) {
mPOut.write(buffer, 0, count);
publishProgress();
}
out.close();
in.close();
mPOut.close();
mPIn.close();
} finally {
mProcess.destroy();
mProcess = null;
}
} catch (IOException e) {
}
return null;
}
#Override
protected void onProgressUpdate(Void... values) {
try {
// Is a line ready to read from the "ping" command?
while (mReader.ready()) {
// This just displays the output, you should typically parse it I guess.
mText.setText(mReader.readLine());
}
} catch (IOException t) {
}
}
}
}
I found a way to execute ping command without root.
Spawns a 'sh' process first, and then execute 'ping' in that shell, the code:
p = new ProcessBuilder("sh").redirectErrorStream(true).start();
DataOutputStream os = new DataOutputStream(p.getOutputStream());
os.writeBytes("ping -c 10 " + host + '\n');
os.flush();
// Close the terminal
os.writeBytes("exit\n");
os.flush();
// read ping replys
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
It works fine on my HTC device with CyanogenMod 7.1.0 (Android 2.3.7)
now i'm making socket connection to connect multiple client to one server. everything fine, i make thread in different class. But when i will fill textView with string from thread activity, i can't. please help
this MainActivity:
public class MainActivity extends Activity {
private static int port = 6000;
TextView txt;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
txt = (TextView) findViewById(R.id.txtCommand);
txt.setText("Server : ");
ServerSocket server1 = null;
Server gameServer = new Server();
try {
server1 = new ServerSocket(port);
// .. server setting should be done here
} catch (IOException e) {
System.out.println("Could not start server!");
// return ;
}
while (true) {
Socket client = null;
try {
client = server1.accept();
gameServer.handleConnection(client);
} catch (IOException e) {
e.printStackTrace();
}
}
}
public class Server {
private ExecutorService executor = Executors.newCachedThreadPool();
public void handleConnection(Socket client) throws IOException {
PlayerConnection newPlayer = new PlayerConnection(this, client);
txt.setText(newPlayer.getuname());
this.executor.execute(newPlayer);
}
// add methods to handle requests from PlayerConnection
}
and this thread adctivity :
public class PlayerConnection implements Runnable {
private Server parent;
private Socket socket;
private PrintWriter out;
private BufferedReader in;
String line;
protected PlayerConnection(Server parent, Socket socket) throws IOException {
this.parent = parent;
this.socket = socket;
this.in = new BufferedReader(new InputStreamReader(socket
.getInputStream()));
this.out = new PrintWriter(new OutputStreamWriter(
socket.getOutputStream()));
}
public void run() {
while(!this.socket.isClosed()) {
try {
//int nextEvent = this.in.readInt();
line = in.readLine();
System.out.println("Server Receive : "
+ line);
out.println("Server Sent :" +line);
System.out.println("SEND : "
+ line);
out.flush();
if (line == null){
this.socket.isClosed();
break;
}
} catch (IOException e) {}
}
I realized that you have a while loop that never ends in your onCreate method. try to move that loop in to your thread. this loop blocks inputs of your application.
while (true) {
Socket client = null;
try {
client = server1.accept();
gameServer.handleConnection(client);
} catch (IOException e) {
e.printStackTrace();
}
you can use handler or runOnUiThread method.