I am developing a simple chat application. Android client and a java desktop server. I am facing a problem that my client sends only a single message to server. Server code is working on java client so only android code have some problem.
Android Client
private static final int SERVERPORT = 5000;
private static final String SERVER_IP = "10.0.2.2";
private Socket socket;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new Thread(new ClientThread()).start();
Button button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
EditText et = (EditText) findViewById(R.id.editText1);
public void onClick(View v) {
try {
PrintWriter out = new PrintWriter(new BufferedWriter(
new OutputStreamWriter(socket.getOutputStream())),
true);
String str = et.getText().toString();
out.println(str);
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException 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();
}
}
}
That is because your thread finishes its job and it's no longer available for you.
Related
I am trying to use from this LINK.
Here is client code :
public class MainActivity extends AppCompatActivity {
private Socket socket;
private static final int SERVERPORT = 5001;
private static final String SERVER_IP = "127.0.0.1";
Button myButton;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myButton = (Button)findViewById(R.id.myButton);
myButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
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();
}
}
});
new Thread(new ClientThread()).start();
}
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();
}
}
}
}
And here server code :
public class MainActivity extends AppCompatActivity {
private ServerSocket serverSocket;
Handler updateConversationHandler;
Thread serverThread = null;
private TextView text;
public static final int SERVERPORT = 6001;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text = (TextView) findViewById(R.id.text2);
updateConversationHandler = new Handler();
this.serverThread = new Thread(new ServerThread());
this.serverThread.start();
}
#Override
protected void onStop() {
super.onStop();
try {
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
class ServerThread implements Runnable {
public void run() {
Socket socket = null;
try {
serverSocket = new ServerSocket(SERVERPORT);
} catch (IOException e) {
e.printStackTrace();
}
while (!Thread.currentThread().isInterrupted()) {
try {
socket = serverSocket.accept();
CommunicationThread commThread = new CommunicationThread(socket);
new Thread(commThread).start();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
class CommunicationThread implements Runnable {
private Socket clientSocket;
private BufferedReader input;
public CommunicationThread(Socket clientSocket) {
this.clientSocket = clientSocket;
try {
this.input = new BufferedReader(new InputStreamReader(this.clientSocket.getInputStream()));
} catch (IOException e) {
e.printStackTrace();
}
}
public void run() {
while (!Thread.currentThread().isInterrupted()) {
try {
String read = input.readLine();
updateConversationHandler.post(new updateUIThread(read));
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
class updateUIThread implements Runnable {
private String msg;
public updateUIThread(String str) {
this.msg = str;
}
#Override
public void run() {
text.setText(text.getText().toString()+"Client Says: "+ msg + "\n");
}
}
}
Get me bellow error and I can't see any message on server :
In your Client code, you haven't created the client-socket, but, you're trying to get the output stream of that socket using socket.getOutputStream(). Since socket is null, hence, your code throws NullPointerException.
So, create a socket object for client to connect to Server as shown below :
public class MainActivity extends AppCompatActivity {
private Socket socket;
private static final int SERVERPORT = 5001;
private static final String SERVER_IP = "127.0.0.1";
Button myButton;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myButton = (Button)findViewById(R.id.myButton);
myButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
try {
EditText et = (EditText) findViewById(R.id.EditText01);
String str = et.getText().toString();
//create socket object as shown below before retrieving the OutputStream object.
socket = new Socket(MainActivity.SERVER_IP,MainActivity.SERVERPORT);
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();
}
}
});
new Thread(new ClientThread()).start();
}
//.... and your code goes on!
I'm trying to connect 2 android device (without server in the middle, just directly like peer-to-peer) which are connected to internet(they are far apart) and send messages.
I thought its like normal socket programming, and connects via IP, seems not.
what I have done so far is this:
I have created 2 android projects, server(receiver) and client(sender)
running in 2 separate devices
Both devices are connected to internet
found the IP of the device with server app running in (using whatismyip.com)
and used it in client app code
but when I want to send a text from client to server, an exception happens in client printing Error3
this is my code:
server:
public class MainActivity extends Activity {
ServerSocket ss = null;
String mClientMsg = "";
Thread myCommsThread = null;
protected static final int MSG_ID = 0x1337;
public static final int SERVERPORT = 6000;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView tv = (TextView) findViewById(R.id.TextView01);
tv.setText("Nothing from client yet");
this.myCommsThread = new Thread(new CommsThread());
this.myCommsThread.start();
}
#Override
protected void onStop() {
super.onStop();
try {
// make sure you close the socket upon exiting
ss.close();
} catch (IOException e) {
e.printStackTrace();
}
}
Handler myUpdateHandler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_ID:
TextView tv = (TextView) findViewById(R.id.TextView01);
tv.setText(mClientMsg);
break;
default:
break;
}
super.handleMessage(msg);
}
};
class CommsThread implements Runnable {
public void run() {
Socket s = null;
try {
ss = new ServerSocket(SERVERPORT );
} catch (IOException e) {
e.printStackTrace();
}
while (!Thread.currentThread().isInterrupted()) {
Message m = new Message();
m.what = MSG_ID;
try {
if (s == null)
s = ss.accept();
BufferedReader input = new BufferedReader(new InputStreamReader(s.getInputStream()));
String st = null;
st = input.readLine();
mClientMsg = st;
myUpdateHandler.sendMessage(m);
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
Client (Error3):
public class MainActivity extends Activity {
private Button bt;
private TextView tv;
private Socket socket;
private String serverIpAddress = "5.114.22.118";
// AND THAT'S MY DEV'T MACHINE WHERE PACKETS TO
// PORT 5000 GET REDIRECTED TO THE SERVER EMULATOR'S
// PORT 6000
private static final int REDIRECTED_SERVERPORT = 80;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bt = (Button) findViewById(R.id.myButton);
tv = (TextView) findViewById(R.id.myTextView);
new Thread(new ClientThread()).start();
bt.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
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);
Log.d("Client", "Client sent message");
} catch (UnknownHostException e) {
tv.setText("Error1");
e.printStackTrace();
} catch (IOException e) {
tv.setText("Error2");
e.printStackTrace();
} catch (Exception e) {
tv.setText("Error3");
e.printStackTrace();
}
}
});
}
class ClientThread implements Runnable {
#Override
public void run() {
try {
InetAddress serverAddr = InetAddress.getByName(serverIpAddress);
socket = new Socket(serverAddr, REDIRECTED_SERVERPORT);
} catch (UnknownHostException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
}
I think this would be more appropriate as a comment, but I don't have enough reputation to comment so I'm providing it as an answer. Is your server connected to a router? whatismyip.com returns the IP address of the router, not the device.
I am developing a client server application. My client is a java application and my server is an android emulator. I want to send message from client to server but no message received on android emulator.
Java Desktop Client Code
Socket s = null;
BufferedReader get = null;
PrintWriter put = null;
try {
s = new Socket("127.0.0.1", 6000);
put = new PrintWriter(s.getOutputStream(), true);
put.println("hi");
}
catch(Exception ex)
{
}
Android Server Code
private ServerSocket serverSocket;
Handler updateConversationHandler;
Thread serverThread = null;
private TextView text;
private EditText textbox;
public static final int SERVERPORT = 6000;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
text = (TextView) findViewById(R.id.text2);
updateConversationHandler = new Handler();
this.serverThread = new Thread(new ServerThread());
this.serverThread.start();
}
#Override
protected void onStop() {
super.onStop();
try {
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
class ServerThread implements Runnable {
public void run() {
Socket socket = null;
try {
serverSocket = new ServerSocket(SERVERPORT);
} catch (IOException e) {
e.printStackTrace();
}
while (!Thread.currentThread().isInterrupted()) {
try {
socket = serverSocket.accept();
CommunicationThread commThread = new CommunicationThread(socket);
new Thread(commThread).start();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
class CommunicationThread implements Runnable {
private Socket clientSocket;
private BufferedReader input;
public CommunicationThread(Socket clientSocket) {
this.clientSocket = clientSocket;
try {
this.input = new BufferedReader(new InputStreamReader(this.clientSocket.getInputStream()));
} catch (IOException e) {
e.printStackTrace();
}
}
public void run() {
while (!Thread.currentThread().isInterrupted()) {
try {
String read = input.readLine();
updateConversationHandler.post(new updateUIThread(read));
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
class updateUIThread implements Runnable {
private String msg;
public updateUIThread(String str) {
this.msg = str;
}
#Override
public void run() {
text.setText(text.getText().toString()+"Client Says: "+ msg + "\n");
}
}
Relevant quote from the documentation (scroll down to the section for Network Address Space:
Each instance of the emulator runs behind a virtual router/firewall service
that isolates it from your development machine's network interfaces and settings
and from the internet. An emulated device can not see your development machine
or other emulator instances on the network. Instead, it sees only that it is
connected through Ethernet to a router/firewall.
The virtual router for each instance manages the 10.0.2/24 network address
space — all addresses managed by the router are in the form of 10.0.2.<xx>,
where <xx> is a number. Addresses within this space are pre-allocated by the
emulator/router as follows:
And then they proceed to show the pre-allocated addresses in a table.
I use these codes for communicating between devices. If i close or kill the client app, the server app gets thousands of useless data. The textView in the server side is full of this: Client says: null. If i close the client twice, the server stops with StackOverFlowError. How can i make the code to dont send this null values when the app stops? Or can i filter the server side to do nothing when getting this data?
Client:
public class Client extends Activity {
private Socket socket;
private static final int SERVERPORT = 5000;
private static final String SERVER_IP = "10.0.2.2";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.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();
}
}
}
}
Server:
public class Server extends Activity {
private ServerSocket serverSocket;
Handler updateConversationHandler;
Thread serverThread = null;
private TextView text;
public static final int SERVERPORT = 1599;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
text = (TextView) findViewById(R.id.text2);
updateConversationHandler = new Handler();
this.serverThread = new Thread(new ServerThread());
this.serverThread.start();
}
#Override
protected void onStop() {
super.onStop();
try {
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
class ServerThread implements Runnable {
public void run() {
Socket socket = null;
try {
serverSocket = new ServerSocket(SERVERPORT);
} catch (IOException e) {
e.printStackTrace();
}
while (!Thread.currentThread().isInterrupted()) {
try {
socket = serverSocket.accept();
CommunicationThread commThread = new CommunicationThread(socket);
new Thread(commThread).start();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
class CommunicationThread implements Runnable {
private Socket clientSocket;
private BufferedReader input;
public CommunicationThread(Socket clientSocket) {
this.clientSocket = clientSocket;
try {
this.input = new BufferedReader(new InputStreamReader(this.clientSocket.getInputStream()));
} catch (IOException e) {
e.printStackTrace();
}
}
public void run() {
while (!Thread.currentThread().isInterrupted()) {
try {
String read = input.readLine();
updateConversationHandler.post(new updateUIThread(read));
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
class updateUIThread implements Runnable {
private String msg;
public updateUIThread(String str) {
this.msg = str;
}
#Override
public void run() {
text.setText(text.getText().toString()+"Client Says: "+ msg + "\n");
}
}
}
I think you should use a delimiter character, to tell the Server your Client it's about to die. Add that character of code in onPause method of your Android Activity/Fragment.
Then in your Server, just get the String or byte and compare it against your Delimiter String/Character and stop the Server listening for the Connection.
while (!Thread.currentThread().isInterrupted()) {
try {
String read = input.readLine();
updateConversationHandler.post(new updateUIThread(read));
} catch (IOException e) {
e.printStackTrace();
}
}
The problem is here. You aren't checking the result of readLine() for null. If it returns null, the peer has closed the connection and you should do likewise, and exit this loop. You can probably get rid of the isInterrupted() test as well.
Also, if you get any IOException other that a read timeout when reading from a socket, the connection is dead and you must close the socket and exit your loop.
I read a thread on the same topic : connecting 2 Emulator Instances
Server Side Code listening on port 6000:
public class NewServerActivity extends Activity {
ServerSocket ss = null;
String mClientMsg = "";
Thread myCommsThread = null;
protected static final int MSG_ID = 0x1337;
public static final int SERVERPORT = 6000;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
TextView tv = (TextView) findViewById(R.id.TextView01);
tv.setText("Nothing from client yet");
this.myCommsThread = new Thread(new CommsThread());
this.myCommsThread.start();
}
#Override
protected void onStop() {
super.onStop();
try {
// make sure you close the socket upon exiting
ss.close();
} catch (IOException e) {
e.printStackTrace();
}
}
Handler myUpdateHandler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_ID:
TextView tv = (TextView) findViewById(R.id.TextView01);
tv.setText(mClientMsg);
break;
default:
break;
}
super.handleMessage(msg);
}
};
class CommsThread implements Runnable {
public void run() {
Socket s = null;
try {
ss = new ServerSocket(SERVERPORT );
} catch (IOException e) {
e.printStackTrace();
}
while (!Thread.currentThread().isInterrupted()) {
Message m = new Message();
m.what = MSG_ID;
try {
if (s == null)
s = ss.accept();
BufferedReader input = new BufferedReader(
new InputStreamReader(s.getInputStream()));
String st = null;
st = input.readLine();
mClientMsg = st;
myUpdateHandler.sendMessage(m);
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
Client side code :
public class NewClientActivity extends Activity {
private Button bt;
private TextView tv;
private Socket socket;
private String serverIpAddress = "10.0.2.2";
// AND THAT'S MY DEV'T MACHINE WHERE PACKETS TO
// PORT 5000 GET REDIRECTED TO THE SERVER EMULATOR'S
// PORT 6000
private static final int REDIRECTED_SERVERPORT = 5000;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
bt = (Button) findViewById(R.id.myButton);
tv = (TextView) findViewById(R.id.myTextView);
try {
InetAddress serverAddr = InetAddress.getByName(serverIpAddress);
socket = new Socket(serverAddr, REDIRECTED_SERVERPORT);
} catch (UnknownHostException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
bt.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
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);
Log.d("Client", "Client sent message");
} catch (UnknownHostException e) {
tv.setText("Error1");
e.printStackTrace();
} catch (IOException e) {
tv.setText("Error2");
e.printStackTrace();
} catch (Exception e) {
tv.setText("Error3");
e.printStackTrace();
}
}
});
}
}
I applied server code on one emulator and client code on another emulator.
Redirected the ports :
telnet localhost 5554
redir add tcp:5000:6000
I ran the server on emulator 5554 and the client on 5556.
My client side is working fine but unfortunately, on starting the server app the emulator shows a message Unfortunately APPLICATION was stopped. And eclipse shows a java.lang.NullPointerException at "s = ss.accept();" line.
Is it somehow related to the configuration of my AVD.
Post your code and the stack trace.
From the one line you posted it sounds like 'ss' is null and you're trying to call accept() on a null.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void mOnClick(View v) {
switch (v.getId()) {
case R.id.myButton:
new Thread(new Runnable() {
#Override
public void run() {
try {
InetAddress serverAddr = InetAddress.getByName(serverIpAddress);
socket = new Socket(serverAddr, REDIRECTED_SERVERPORT);
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);
Log.d("Client", "Client sent message");
out.close();
socket.close();
} catch (UnknownHostException e) {
//tv.setText("Error1");
e.printStackTrace();
} catch (IOException e) {
//tv.setText("Error2");
e.printStackTrace();
} catch (Exception e) {
//tv.setText("Error3");
e.printStackTrace();
}
}
}).start();
break;
}
}
need xml change
android:onClick="mOnClick"
<Button
android:id="#+id/myButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="mOnClick"
android:text="start" />
it's because try to run connect() method in main Thread