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Null pointer exception probably due to synchronisation issues; problem in starting activity

Madhu Nandan

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posted 14 years ago

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Swastik Dey wrote:Make these two changes and see if you get any difference
public class MessageConsumer extends TimerTask{ private TCPListener _listener; TcpServiceHandler _handler; Activity act; public MessageConsumer(Activity act,TCPListener listener){ this._listener=listener; this.act=act; } @Override public synchronized void run() { // TODO Auto-generated method stub try { this.act.runOnUiThread(new Runnable(){ public void run() { // TODO Auto-generated method stub _handler=new TcpServiceHandler(_listener); _handler.execute("192.168.62.23"); } }); } catch (Throwable e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

_timer=new Timer(); MessageConsumer mc=new MessageConsumer(this,this); //check after every one second _timer.scheduleAtFixedRate(mc, 0, 1000);

I tried with these changes. But still I receive only the first message and nothing after that (2nd message is sent 5 seconds after 1st message).

LogCat:

01-13 09:45:13.160: DEBUG/AndroidRuntime(335): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<<
01-13 09:45:13.160: DEBUG/AndroidRuntime(335): CheckJNI is ON
01-13 09:45:13.439: DEBUG/AndroidRuntime(335): --- registering native functions ---
01-13 09:45:14.240: INFO/ActivityManager(58): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.example.android.TCPListen/.TCPListen }
01-13 09:45:14.320: DEBUG/AndroidRuntime(335): Shutting down VM
01-13 09:45:14.349: DEBUG/dalvikvm(335): Debugger has detached; object registry had 1 entries
01-13 09:45:14.410: INFO/AndroidRuntime(335): NOTE: attach of thread 'Binder Thread #3' failed
01-13 09:45:14.429: INFO/ActivityManager(58): Start proc com.example.android.TCPListen for activity com.example.android.TCPListen/.TCPListen: pid=342 uid=10037 gids={3003}
01-13 09:45:15.180: INFO/ActivityManager(58): Displayed activity com.example.android.TCPListen/.TCPListen: 862 ms (total 862 ms)
01-13 09:45:15.309: DEBUG/TCP(342): C: Connecting...
01-13 09:45:15.309: DEBUG/TCP(342): C: Connecting...
01-13 09:45:15.479: DEBUG/TCP(342): C: Receiving...
01-13 09:45:15.510: DEBUG/TCP(342): C: Receiving...
01-13 09:45:15.530: INFO/global(342): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.
01-13 09:45:15.540: INFO/global(342): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.
01-13 09:45:15.549: DEBUG/TCP(342): C: Done danaadan.
01-13 09:45:15.570: DEBUG/TCP(342): Std parser <MSG><N>shiftDirection</N><V>0</V></MSG>
01-13 09:45:15.589: DEBUG/TCP(342): Inside Std parser shiftDirection 0
01-13 09:45:15.589: DEBUG/TCP(342): Inside actionOnData shiftDirection 0
01-13 09:45:15.599: DEBUG/TCP(342): Message with wrong value
01-13 09:45:15.599: DEBUG/TCP(342): Just outside Std parser shiftDirection 0
01-13 09:45:16.043: DEBUG/TCP(342): C: Connecting...
01-13 09:45:16.050: DEBUG/TCP(342): C: Receiving...
01-13 09:45:16.050: INFO/global(342): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.
01-13 09:45:17.081: DEBUG/TCP(342): C: Connecting...
01-13 09:45:17.129: DEBUG/TCP(342): C: Receiving...
01-13 09:45:17.129: INFO/global(342): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.
01-13 09:45:18.049: DEBUG/TCP(342): C: Connecting...
01-13 09:45:18.070: DEBUG/TCP(342): C: Receiving...
01-13 09:45:18.070: INFO/global(342): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.
01-13 09:45:18.992: DEBUG/TCP(342): C: Connecting...
01-13 09:45:19.009: DEBUG/TCP(342): C: Receiving...
01-13 09:45:19.009: INFO/global(342): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.
01-13 09:45:20.469: DEBUG/dalvikvm(123): GC_EXPLICIT freed 180 objects / 9384 bytes in 198ms
01-13 09:45:20.550: DEBUG/TCP(342): C: Done danaadan.
01-13 09:45:20.550: DEBUG/TCP(342): C: Done danaadan.
01-13 09:45:20.570: DEBUG/TCP(342): C: Done danaadan.
01-13 09:45:20.570: DEBUG/TCP(342): C: Done danaadan.
01-13 09:45:20.580: DEBUG/TCP(342): C: Done danaadan.
01-13 09:45:20.590: DEBUG/TCP(342): Std parser null
01-13 09:45:20.599: WARN/System.err(342): java.lang.NullPointerException
01-13 09:45:20.621: WARN/System.err(342):     at com.example.android.TCPListen.TCPListen.callCompleted(TCPListen.java:112)
01-13 09:45:20.621: WARN/System.err(342):     at com.example.android.TCPListen.TcpServiceHandler.onPostExecute(TcpServiceHandler.java:77)
01-13 09:45:20.631: WARN/System.err(342):     at com.example.android.TCPListen.TcpServiceHandler.onPostExecute(TcpServiceHandler.java:1)
01-13 09:45:20.640: WARN/System.err(342):     at android.os.AsyncTask.finish(AsyncTask.java:417)
01-13 09:45:20.640: WARN/System.err(342):     at android.os.AsyncTask.access$300(AsyncTask.java:127)
01-13 09:45:20.650: WARN/System.err(342):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
01-13 09:45:20.650: WARN/System.err(342):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-13 09:45:20.660: WARN/System.err(342):     at android.os.Looper.loop(Looper.java:123)
01-13 09:45:20.670: WARN/System.err(342):     at android.app.ActivityThread.main(ActivityThread.java:4627)
01-13 09:45:20.670: WARN/System.err(342):     at java.lang.reflect.Method.invokeNative(Native Method)
01-13 09:45:20.670: WARN/System.err(342):     at java.lang.reflect.Method.invoke(Method.java:521)
01-13 09:45:20.680: WARN/System.err(342):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-13 09:45:20.689: WARN/System.err(342):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-13 09:45:20.699: WARN/System.err(342):     at dalvik.system.NativeStart.main(Native Method)
01-13 09:45:20.699: DEBUG/TCP(342): Just outside Std parser shiftDirection 0
01-13 09:45:20.699: DEBUG/TCP(342): Std parser null
01-13 09:45:20.711: WARN/System.err(342): java.lang.NullPointerException
01-13 09:45:20.711: WARN/System.err(342):     at com.example.android.TCPListen.TCPListen.callCompleted(TCPListen.java:112)
01-13 09:45:20.730: WARN/System.err(342):     at com.example.android.TCPListen.TcpServiceHandler.onPostExecute(TcpServiceHandler.java:77)
01-13 09:45:20.730: WARN/System.err(342):     at com.example.android.TCPListen.TcpServiceHandler.onPostExecute(TcpServiceHandler.java:1)
01-13 09:45:20.730: WARN/System.err(342):     at android.os.AsyncTask.finish(AsyncTask.java:417)
01-13 09:45:20.740: WARN/System.err(342):     at android.os.AsyncTask.access$300(AsyncTask.java:127)
01-13 09:45:20.750: WARN/System.err(342):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
01-13 09:45:20.750: WARN/System.err(342):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-13 09:45:20.760: WARN/System.err(342):     at android.os.Looper.loop(Looper.java:123)
01-13 09:45:20.760: WARN/System.err(342):     at android.app.ActivityThread.main(ActivityThread.java:4627)
01-13 09:45:20.760: WARN/System.err(342):     at java.lang.reflect.Method.invokeNative(Native Method)
01-13 09:45:20.770: WARN/System.err(342):     at java.lang.reflect.Method.invoke(Method.java:521)
01-13 09:45:20.770: WARN/System.err(342):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-13 09:45:20.770: WARN/System.err(342):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-13 09:45:20.780: WARN/System.err(342):     at dalvik.system.NativeStart.main(Native Method)
01-13 09:45:20.780: DEBUG/TCP(342): Just outside Std parser shiftDirection 0
01-13 09:45:20.850: DEBUG/TCP(342): Std parser null
01-13 09:45:20.850: WARN/System.err(342): java.lang.NullPointerException
01-13 09:45:20.850: DEBUG/TCP(342): C: Connecting...
01-13 09:45:20.860: WARN/System.err(342):     at com.example.android.TCPListen.TCPListen.callCompleted(TCPListen.java:112)
01-13 09:45:20.860: WARN/System.err(342):     at com.example.android.TCPListen.TcpServiceHandler.onPostExecute(TcpServiceHandler.java:77)
01-13 09:45:20.860: WARN/System.err(342):     at com.example.android.TCPListen.TcpServiceHandler.onPostExecute(TcpServiceHandler.java:1)
01-13 09:45:20.870: WARN/System.err(342):     at android.os.AsyncTask.finish(AsyncTask.java:417)
01-13 09:45:20.870: WARN/System.err(342):     at android.os.AsyncTask.access$300(AsyncTask.java:127)
01-13 09:45:20.870: WARN/System.err(342):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
01-13 09:45:20.879: WARN/System.err(342):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-13 09:45:20.879: WARN/System.err(342):     at android.os.Looper.loop(Looper.java:123)
01-13 09:45:20.879: WARN/System.err(342):     at android.app.ActivityThread.main(ActivityThread.java:4627)
01-13 09:45:20.879: WARN/System.err(342):     at java.lang.reflect.Method.invokeNative(Native Method)
01-13 09:45:20.889: WARN/System.err(342):     at java.lang.reflect.Method.invoke(Method.java:521)
01-13 09:45:20.889: WARN/System.err(342):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-13 09:45:20.889: WARN/System.err(342):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-13 09:45:20.900: WARN/System.err(342):     at dalvik.system.NativeStart.main(Native Method)
01-13 09:45:20.900: DEBUG/TCP(342): Just outside Std parser shiftDirection 0
01-13 09:45:20.900: DEBUG/TCP(342): Std parser null
01-13 09:45:20.900: WARN/System.err(342): java.lang.NullPointerException
01-13 09:45:20.910: WARN/System.err(342):     at com.example.android.TCPListen.TCPListen.callCompleted(TCPListen.java:112)
01-13 09:45:20.910: WARN/System.err(342):     at com.example.android.TCPListen.TcpServiceHandler.onPostExecute(TcpServiceHandler.java:77)
01-13 09:45:20.910: WARN/System.err(342):     at com.example.android.TCPListen.TcpServiceHandler.onPostExecute(TcpServiceHandler.java:1)
01-13 09:45:20.910: WARN/System.err(342):     at android.os.AsyncTask.finish(AsyncTask.java:417)
01-13 09:45:20.919: WARN/System.err(342):     at android.os.AsyncTask.access$300(AsyncTask.java:127)
01-13 09:45:20.919: WARN/System.err(342):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
01-13 09:45:20.929: WARN/System.err(342):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-13 09:45:20.929: WARN/System.err(342):     at android.os.Looper.loop(Looper.java:123)
01-13 09:45:20.929: WARN/System.err(342):     at android.app.ActivityThread.main(ActivityThread.java:4627)
01-13 09:45:20.939: WARN/System.err(342):     at java.lang.reflect.Method.invokeNative(Native Method)
01-13 09:45:20.939: WARN/System.err(342):     at java.lang.reflect.Method.invoke(Method.java:521)
01-13 09:45:20.939: WARN/System.err(342):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-13 09:45:20.939: WARN/System.err(342):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-13 09:45:20.951: WARN/System.err(342):     at dalvik.system.NativeStart.main(Native Method)
01-13 09:45:20.951: DEBUG/TCP(342): Just outside Std parser shiftDirection 0
01-13 09:45:20.951: DEBUG/TCP(342): Std parser null
01-13 09:45:20.951: WARN/System.err(342): java.lang.NullPointerException
01-13 09:45:20.960: WARN/System.err(342):     at com.example.android.TCPListen.TCPListen.callCompleted(TCPListen.java:112)
01-13 09:45:20.960: WARN/System.err(342):     at com.example.android.TCPListen.TcpServiceHandler.onPostExecute(TcpServiceHandler.java:77)
01-13 09:45:20.960: WARN/System.err(342):     at com.example.android.TCPListen.TcpServiceHandler.onPostExecute(TcpServiceHandler.java:1)
01-13 09:45:20.970: WARN/System.err(342):     at android.os.AsyncTask.finish(AsyncTask.java:417)
01-13 09:45:20.970: WARN/System.err(342):     at android.os.AsyncTask.access$300(AsyncTask.java:127)
01-13 09:45:20.970: WARN/System.err(342):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
01-13 09:45:20.980: WARN/System.err(342):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-13 09:45:20.980: WARN/System.err(342):     at android.os.Looper.loop(Looper.java:123)
01-13 09:45:20.980: WARN/System.err(342):     at android.app.ActivityThread.main(ActivityThread.java:4627)
01-13 09:45:20.980: WARN/System.err(342):     at java.lang.reflect.Method.invokeNative(Native Method)
01-13 09:45:20.990: WARN/System.err(342):     at java.lang.reflect.Method.invoke(Method.java:521)
01-13 09:45:20.990: WARN/System.err(342):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-13 09:45:20.990: WARN/System.err(342):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-13 09:45:21.000: WARN/System.err(342):     at dalvik.system.NativeStart.main(Native Method)
01-13 09:45:21.000: DEBUG/TCP(342): Just outside Std parser shiftDirection 0
01-13 09:45:21.050: DEBUG/TCP(342): C: Connecting...
01-13 09:45:22.020: DEBUG/TCP(342): C: Connecting...
01-13 09:45:23.030: DEBUG/TCP(342): C: Connecting...
01-13 09:45:24.029: DEBUG/TCP(342): C: Connecting...
01-13 09:45:25.501: DEBUG/dalvikvm(239): GC_EXPLICIT freed 127 objects / 9672 bytes in 165ms
01-13 09:45:30.530: DEBUG/dalvikvm(247): GC_EXPLICIT freed 719 objects / 53464 bytes in 200ms
01-13 09:45:35.020: DEBUG/TCP(342): C: Connecting...
01-13 09:45:36.051: DEBUG/TCP(342): C: Connecting...
01-13 09:45:37.069: DEBUG/TCP(342): C: Connecting...
01-13 09:45:38.020: DEBUG/TCP(342): C: Connecting...
01-13 09:45:39.049: DEBUG/TCP(342): C: Connecting...
01-13 09:45:40.059: DEBUG/TCP(342): C: Connecting...
01-13 09:45:41.021: DEBUG/TCP(342): C: Connecting...
01-13 09:45:42.030: DEBUG/TCP(342): C: Connecting...
01-13 09:45:43.060: DEBUG/TCP(342): C: Connecting...
01-13 09:45:44.001: DEBUG/TCP(342): C: Connecting...
01-13 09:45:44.840: WARN/KeyCharacterMap(342): No keyboard for id 0
01-13 09:45:44.849: WARN/KeyCharacterMap(342): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
01-13 09:45:45.679: DEBUG/TCP(342): C: Connecting...
01-13 09:45:46.060: DEBUG/TCP(342): C: Connecting...
01-13 09:45:46.749: INFO/ActivityManager(58): Force stopping package com.example.android.TCPListen uid=10037
01-13 09:45:46.749: INFO/Process(58): Sending signal. PID: 342 SIG: 9
01-13 09:45:52.131: DEBUG/dalvikvm(159): GC_EXPLICIT freed 1619 objects / 82792 bytes in 232ms
01-13 09:46:02.240: WARN/KeyCharacterMap(123): No keyboard for id 0
01-13 09:46:02.250: WARN/KeyCharacterMap(123): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
01-13 09:46:02.770: INFO/ActivityManager(58): Displayed activity com.android.settings/.ManageApplications: 243485 ms (total 243485 ms)
01-13 09:46:05.180: INFO/ActivityManager(58): Starting activity: Intent { act=android.intent.action.VIEW cmp=com.android.settings/.InstalledAppDetails (has extras) }
01-13 09:46:05.830: INFO/ActivityManager(58): Displayed activity com.android.settings/.InstalledAppDetails: 578 ms (total 578 ms)

Swastik Dey

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posted 14 years ago

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Madhu

It seems we need to think this in a little different way, i.e. instead of push from server, it can be pull from client. At a specific time interval the client sends a request to server, and the server based on the message validity sends back a response to client.
As per the following code the server will send two different messages at 10 seconds interval.

public class TCPSendServer implements Runnable{
	public static final String SERVERIP = "192.168.62.23";
    public static final int SERVERPORT = 1200;

public void run() {
         try {
        	 System.out.println("S: Connecting...");
             ServerSocket serverSocket = new ServerSocket(SERVERPORT);
             //String msg = "<MSG><N>shiftDirection</N><V>1</V></MSG>";
             String msg1 = "<MSG><N>shiftDirection</N><V>0</V></MSG>";
             String msg2 = "SD<!N><V>0<!V><!MSG>";
			 int ktr=1;
            while (true)	{
            	 Socket client = serverSocket.accept();

try {
            		  BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
                     String str = in.readLine();
                     System.out.println("Messaged received::"+str);
            		  //System.out.println("S: Sending: '" + msg2+ "'");
     		    	  PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(client.getOutputStream())),true);
     		    	  if(ktr==1){
						System.out.println("S: Sending: '" + msg2+ "'");
     		    	  	out.println(msg2);
     		    	  	ktr++;
					  }
					  else{
						  System.out.println("S: Sending: '" + msg1+ "'");
						  out.println(msg1);
						  ktr=1;
					  }
     		    	  out.flush();
     		    	  System.out.println("S: Sent.");
     		    	  System.out.println("S: Done.");
                    } catch(Exception e) {
                        System.out.println("S: Error");
                        e.printStackTrace();
                    } //finally {
                      //	client.close();
                    //}
             }
         } catch (Exception e) {
             System.out.println("S: First try error");
             e.printStackTrace();
         }
    }

public static void main (String a[]) {
    	Thread desktopServerThread = new Thread(new TCPSendServer());
    	desktopServerThread.start();
    }
}

public class TcpServiceHandler extends AsyncTask<String, Integer, String>{  
    TCPListener _listener;      
    private static Socket _socket;
    public TcpServiceHandler(TCPListener listener){  
        _listener=listener;       
    }  
      
    //@Override  
    //protected void onPreExecute() {  
        //you may wish to show a wait screen here  
    //}  	       
      
    @Override  
    protected String doInBackground(String... params) {  
        //you should do the desktop app connectivity part here  
   	 
        String str = "";  
        try{	        	 
            //response=//stream received from desktop app  
       	 
       	 //System.out.println("C: Connecting...");
       	// Socket socket = new Socket(serverAddr, 1200);
            System.out.println("C: Receiving...");

try {
           		InetAddress serverAddr = InetAddress.getByName("192.168.1.123");
           		Socket socket = new Socket(serverAddr, 1200);
           		PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(socket.getOutputStream())),true);
           		out.println("Send me message");
           		out.flush();
           		  	BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                     str = in.readLine();
                     Log.d("TCP","C: Received: ");
                     //in.close();
                     //return str;
                     //Pass str to main activity for parsing
                     //mHandler.obtainMessage(TCPIPCommn.INCOMING_MESSAGE, str).sendToTarget();                    
                   } catch(Exception e) {
                   	Log.d("TCP","S: Error", e);
                       e.printStackTrace();
                   } finally {
                   	//socket.close();
                   	Log.d("TCP","C: Done danaadan.");
                   }	             	 
        }  
        catch(Exception e){}  
        return str;  
    }  
      
    @Override  
    protected void onPostExecute(String responseMessage) {  
        //notify your activity that you have received message from desktop app  
        _listener.callCompleted(responseMessage);  
    }  
}

Swastik

Madhu Nandan

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posted 14 years ago

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Swastik Dey wrote:Make these two changes and see if you get any difference
public class MessageConsumer extends TimerTask{ private TCPListener _listener; TcpServiceHandler _handler; Activity act; public MessageConsumer(Activity act,TCPListener listener){ this._listener=listener; this.act=act; } @Override public synchronized void run() { // TODO Auto-generated method stub try { this.act.runOnUiThread(new Runnable(){ public void run() { // TODO Auto-generated method stub _handler=new TcpServiceHandler(_listener); _handler.execute("192.168.1.123"); } }); } catch (Throwable e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

_timer=new Timer(); MessageConsumer mc=new MessageConsumer(this,this); //check after every one second _timer.scheduleAtFixedRate(mc, 0, 1000);

I think the TimerTask is running every second and each time it runs, it tries to connect on a different socket. The port number is fixed (1200 in this case) but the socket number keeps changing every time it connects. What I need to do is connect just once, then keep looking for new incoming messages. I have to run the part which looks for new incoming messages as/in a TimerTask. I think this is the cause of the problem. What do you feel?

Madhu Nandan

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posted 14 years ago

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Swastik Dey wrote:Madhu

It seems we need to think this in a little different way, i.e. instead of push from server, it can be pull from client. At a specific time interval the client sends a request to server, and the server based on the message validity sends back a response to client.
As per the following code the server will send two different messages at 10 seconds interval.

public class TCPSendServer implements Runnable{ public static final String SERVERIP = "192.168.62.23"; public static final int SERVERPORT = 1200; public void run() { try { System.out.println("S: Connecting..."); ServerSocket serverSocket = new ServerSocket(SERVERPORT); //String msg = "<MSG><N>shiftDirection</N><V>1</V></MSG>"; String msg1 = "<MSG><N>shiftDirection</N><V>0</V></MSG>"; String msg2 = "SD<!N><V>0<!V><!MSG>"; int ktr=1; while (true) { Socket client = serverSocket.accept(); try { BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream())); String str = in.readLine(); System.out.println("Messaged received::"+str); //System.out.println("S: Sending: '" + msg2+ "'"); PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(client.getOutputStream())),true); if(ktr==1){ System.out.println("S: Sending: '" + msg2+ "'"); out.println(msg2); ktr++; } else{ System.out.println("S: Sending: '" + msg1+ "'"); out.println(msg1); ktr=1; } out.flush(); System.out.println("S: Sent."); System.out.println("S: Done."); } catch(Exception e) { System.out.println("S: Error"); e.printStackTrace(); } //finally { // client.close(); //} } } catch (Exception e) { System.out.println("S: First try error"); e.printStackTrace(); } } public static void main (String a[]) { Thread desktopServerThread = new Thread(new TCPSendServer()); desktopServerThread.start(); } }

public class TcpServiceHandler extends AsyncTask<String, Integer, String>{ TCPListener _listener; private static Socket _socket; public TcpServiceHandler(TCPListener listener){ _listener=listener; } //@Override //protected void onPreExecute() { //you may wish to show a wait screen here //} @Override protected String doInBackground(String... params) { //you should do the desktop app connectivity part here String str = ""; try{ //response=//stream received from desktop app //System.out.println("C: Connecting..."); // Socket socket = new Socket(serverAddr, 1200); System.out.println("C: Receiving..."); try { InetAddress serverAddr = InetAddress.getByName("192.168.1.123"); Socket socket = new Socket(serverAddr, 1200); PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(socket.getOutputStream())),true); out.println("Send me message"); out.flush(); BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream())); str = in.readLine(); Log.d("TCP","C: Received: "); //in.close(); //return str; //Pass str to main activity for parsing //mHandler.obtainMessage(TCPIPCommn.INCOMING_MESSAGE, str).sendToTarget(); } catch(Exception e) { Log.d("TCP","S: Error", e); e.printStackTrace(); } finally { //socket.close(); Log.d("TCP","C: Done danaadan."); } } catch(Exception e){} return str; } @Override protected void onPostExecute(String responseMessage) { //notify your activity that you have received message from desktop app _listener.callCompleted(responseMessage); } }

Hi Swastik,

I put only the data reading part in doInBackground of AsyncTask in a TimerTask. But still I can read only the first message sent from the server and not any message sent after that. See the AsyncTask code and LogCat below. If you have suggestions, please tell me.

public class TcpServiceHandler extends AsyncTask<String, Integer, String>{  
	     TCPListener _listener;
	     public BufferedReader in;
	     public String str;
	     public TcpServiceHandler(TCPListener listener){  
	         _listener=listener;  
	     }  
	       
	     //@Override  
	     //protected void onPreExecute() {  
	         //you may wish to show a wait screen here  
	     //}  	       
	       
	     @Override  
	     protected String doInBackground(String... params) {  
	         //String str;
	    	 final int delay = 1000;
	    	 final Timer _timer = new Timer();
	         //while (true)	{
	         try{	        	 
	             //response=//stream received from desktop app  
	        	 InetAddress serverAddr = InetAddress.getByName("192.168.62.23");
	        	 Log.d("TCP", "C: Connecting...");
	        	 final Socket socket = new Socket(serverAddr, 1200);
	        	 Log.d("TCP", "C: Receiving...");
	        	 //char[] buffer = new char[1024];
	        	 //int bytes;
	             //String end = "<!MSG>";
	             //StringBuilder curMsg = new StringBuilder();

try {
	            		  //while(true)	{
	        	 
	            	
	        		in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
	            	_timer.scheduleAtFixedRate(new TimerTask()	{	            		
	            	    public void run(){	            				  
	            		try {
							str = in.readLine();
						} catch (IOException e) {
							// TODO Auto-generated catch block
							e.printStackTrace();
						}            		
	            		}	            			  
	            		  }, 0, delay);
	            		  //return str1;
	        	 
	                      //BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
	                      //str = in.readLine();
	                      //while (-1 != (bytes = in.read(buffer))) {
	                  	  //  curMsg.append(new String(buffer, 0, bytes));
	                  	  //  int endIdx = curMsg.indexOf(end);
	                  	  //  if (endIdx != -1) {
	                  	  //      str = curMsg.substring(0, endIdx + end.length());
	                  	  //      curMsg.delete(0, endIdx + end.length());	                      
	                  	  //  }
	                      //}
	                      //return str; 
	            		  //}
	                      //return str;
	                      //Pass str to main activity for parsing
	                      //mHandler.obtainMessage(TCPIPCommn.INCOMING_MESSAGE, str).sendToTarget();                    
	                    } catch(Exception e) {
	                    	//Log.d("TCP","C: Error", e);
	                        //e.printStackTrace();
	                    } finally {
	                    	socket.close();
	                    	Log.d("TCP","C: Done danaadan.");
	                    }	             	 
	         }  
	         catch(Exception e){}  
	         return str; 
	         
	     //}  
	     }    
	       
	     @Override  
	     protected void onPostExecute(String responseMessage) {
	    	 //notify your activity that you have received message from desktop app  
	         _listener.callCompleted(responseMessage);  
	     }  
	 }

LogCat

01-13 16:02:49.966: DEBUG/AndroidRuntime(442): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<<
01-13 16:02:49.966: DEBUG/AndroidRuntime(442): CheckJNI is ON
01-13 16:02:50.157: DEBUG/AndroidRuntime(442): --- registering native functions ---
01-13 16:02:50.947: INFO/ActivityManager(58): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.example.android.TCPListen/.TCPListen }
01-13 16:02:50.978: INFO/ActivityManager(58): Start proc com.example.android.TCPListen for activity com.example.android.TCPListen/.TCPListen: pid=448 uid=10037 gids={3003}
01-13 16:02:51.027: DEBUG/AndroidRuntime(442): Shutting down VM
01-13 16:02:51.068: DEBUG/dalvikvm(442): Debugger has detached; object registry had 1 entries
01-13 16:02:51.077: INFO/AndroidRuntime(442): NOTE: attach of thread 'Binder Thread #3' failed
01-13 16:02:51.846: INFO/ActivityManager(58): Displayed activity com.example.android.TCPListen/.TCPListen: 883 ms (total 883 ms)
01-13 16:02:52.016: DEBUG/TCP(448): C: Connecting...
01-13 16:02:52.087: DEBUG/TCP(448): C: Receiving...
01-13 16:02:52.127: INFO/global(448): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.
01-13 16:02:52.157: DEBUG/TCP(448): C: Done danaadan.
01-13 16:02:52.157: DEBUG/TCP(448): Std parser <MSG><N>shiftDirection</N><V>1</V></MSG>
01-13 16:02:52.226: DEBUG/TCP(448): Inside Std parser shiftDirection 1
01-13 16:02:52.226: DEBUG/TCP(448): in actionOnData shiftDirection 1
01-13 16:02:52.238: INFO/ActivityManager(58): Starting activity: Intent { cmp=com.example.android.TCPListen/.Images }
01-13 16:02:52.247: DEBUG/TCP(448): Just outside Std parser shiftDirection 1
01-13 16:02:52.778: INFO/ActivityManager(58): Displayed activity com.example.android.TCPListen/.Images: 457 ms (total 457 ms)
01-13 16:02:53.156: WARN/System.err(448): java.net.SocketException: Bad file number
01-13 16:02:53.156: WARN/System.err(448):     at org.apache.harmony.luni.platform.OSNetworkSystem.readSocketImpl(Native Method)
01-13 16:02:53.156: WARN/System.err(448):     at org.apache.harmony.luni.platform.OSNetworkSystem.read(OSNetworkSystem.java:358)
01-13 16:02:53.156: WARN/System.err(448):     at org.apache.harmony.luni.net.PlainSocketImpl.read(PlainSocketImpl.java:561)
01-13 16:02:53.156: WARN/System.err(448):     at org.apache.harmony.luni.net.SocketInputStream.read(SocketInputStream.java:88)
01-13 16:02:53.156: WARN/System.err(448):     at java.io.InputStreamReader.read(InputStreamReader.java:275)
01-13 16:02:53.156: WARN/System.err(448):     at java.io.BufferedReader.fillBuf(BufferedReader.java:155)
01-13 16:02:53.156: WARN/System.err(448):     at java.io.BufferedReader.readLine(BufferedReader.java:386)
01-13 16:02:53.156: WARN/System.err(448):     at com.example.android.TCPListen.TcpServiceHandler$1.run(TcpServiceHandler.java:53)
01-13 16:02:53.156: WARN/System.err(448):     at java.util.Timer$TimerImpl.run(Timer.java:289)
01-13 16:02:54.187: WARN/System.err(448): java.net.SocketException: Bad file number
01-13 16:02:54.187: WARN/System.err(448):     at org.apache.harmony.luni.platform.OSNetworkSystem.readSocketImpl(Native Method)
01-13 16:02:54.207: WARN/System.err(448):     at org.apache.harmony.luni.platform.OSNetworkSystem.read(OSNetworkSystem.java:358)
01-13 16:02:54.207: WARN/System.err(448):     at org.apache.harmony.luni.net.PlainSocketImpl.read(PlainSocketImpl.java:561)
01-13 16:02:54.226: WARN/System.err(448):     at org.apache.harmony.luni.net.SocketInputStream.read(SocketInputStream.java:88)
01-13 16:02:54.226: WARN/System.err(448):     at java.io.InputStreamReader.read(InputStreamReader.java:275)
01-13 16:02:54.226: WARN/System.err(448):     at java.io.BufferedReader.fillBuf(BufferedReader.java:155)
01-13 16:02:54.238: WARN/System.err(448):     at java.io.BufferedReader.readLine(BufferedReader.java:386)
01-13 16:02:54.247: WARN/System.err(448):     at com.example.android.TCPListen.TcpServiceHandler$1.run(TcpServiceHandler.java:53)
01-13 16:02:54.247: WARN/System.err(448):     at java.util.Timer$TimerImpl.run(Timer.java:289)
01-13 16:02:55.177: WARN/System.err(448): java.net.SocketException: Bad file number
01-13 16:02:55.177: WARN/System.err(448):     at org.apache.harmony.luni.platform.OSNetworkSystem.readSocketImpl(Native Method)
01-13 16:02:55.187: WARN/System.err(448):     at org.apache.harmony.luni.platform.OSNetworkSystem.read(OSNetworkSystem.java:358)
01-13 16:02:55.197: WARN/System.err(448):     at org.apache.harmony.luni.net.PlainSocketImpl.read(PlainSocketImpl.java:561)

Swastik Dey

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Do you find anything wrong with the approach that I told you, i.e. instead of push to device go for pull from device.

Swastik

Madhu Nandan

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Swastik Dey wrote:Do you find anything wrong with the approach that I told you, i.e. instead of push to device go for pull from device.

About pull from server, I feel it is a good approach. Will try and inform you.

Regarding current situation, I think the TimerTask is running every second and each time it runs, it tries to connect on a different socket. The port number is fixed (1200 in this case) but the socket number keeps changing every time it connects. What I need to do is connect just once, then keep looking for new incoming messages. I have to run the part which looks for new incoming messages as/in a TimerTask. I think this is the cause of the problem. What do you feel?

Swastik Dey

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Probably you are right. Another point is in the pull from server approach code maintainability will be better and overhead on server is less, because it will send a response only when it gets a request.

Swastik

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Swastik Dey wrote:Probably you are right. Another point is in the pull from server approach code maintainability will be better and overhead on server is less, because it will send a response only when it gets a request.

I will explain my situation. The Android app will run and communicate with the application running in the car PC. And the messages from the car PC are sent randomly based on how the car is being driven. For example, shiftDirection is a message which will be set to 1 and sent when the RPM is high enough and the driver has not shifted to the next gear. The Android app has to just respond to the messages it receives and do actions like show an image or display driver assistance info, etc. So the Android app really has no control over the messages it can receive. So will the pull approach really work here?

Swastik Dey

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I hope this time it solves your purpose

public class TcpServiceHandler implements Runnable{
    TCPListener _listener;          
    private Activity _act;
    public TcpServiceHandler(TCPListener listener,Activity act){  
        _listener=listener;
        _act=act;
    }

public synchronized void run() {
		// TODO Auto-generated method stub
		
		//if(socket==null){  
   			try {
				InetAddress serverAddr = InetAddress.getByName("192.168.1.123");
				Socket socket= new Socket(serverAddr, 1200);
 		//
				while(true){
				 try {
				   		
				   		BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
				        final String str = in.readLine();
				        this._act.runOnUiThread(new Runnable(){

public void run() {
								 _listener.callCompleted(str);
							}
							
						});
				        				       
				 }
				 catch(Exception e){
					 e.printStackTrace();
				 }
				}
			} catch (UnknownHostException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
	}  
}

import java.net.*;
import java.io.*;
public class TCPSendServer implements Runnable{
	public static final String SERVERIP = "192.168.62.23";
    public static final int SERVERPORT = 1200;

public void run() {
         try {
        	 System.out.println("S: Connecting...");
             ServerSocket serverSocket = new ServerSocket(SERVERPORT);
             //String msg = "<MSG><N>shiftDirection</N><V>1</V></MSG>";
             String msg1 = "<MSG><N>shiftDirection</N><V>0</V></MSG>";
             String msg2 = "SD<!N><V>0<!V><!MSG>";
			 int ktr=1;
			  Socket client = serverSocket.accept();
            while (true)	{

try {
     		    	  PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(client.getOutputStream())),true);
     		    	  if(ktr==1){
						System.out.println("S: Sending: '" + msg2+ "'");
     		    	  	out.println(msg2);
     		    	  	ktr++;
					  }
					  else{
						  System.out.println("S: Sending: '" + msg1+ "'");
						  out.println(msg1);
						  ktr=1;
					  }
     		    	  out.flush();
     		    	  System.out.println("S: Sent.");
     		    	  System.out.println("S: Done.");
     		    	  Thread.sleep(1000);

} catch(Exception e) {
                        System.out.println("S: Error");
                        e.printStackTrace();
                    } //finally {
                      //	client.close();
                    //}
             }
         } catch (Exception e) {
             System.out.println("S: First try error");
             e.printStackTrace();
         }
    }

public static void main (String a[]) {
    	Thread desktopServerThread = new Thread(new TCPSendServer());
    	desktopServerThread.start();
    }
}

Swastik

Madhu Nandan

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Sorry...nothing here

Madhu Nandan

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Swastik Dey wrote:I hope this time it solves your purpose
public class TcpServiceHandler implements Runnable{ TCPListener _listener; private Activity _act; public TcpServiceHandler(TCPListener listener,Activity act){ _listener=listener; _act=act; } public synchronized void run() { // TODO Auto-generated method stub //if(socket==null){ try { InetAddress serverAddr = InetAddress.getByName("192.168.1.123"); Socket socket= new Socket(serverAddr, 1200); // while(true){ try { BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream())); final String str = in.readLine(); this._act.runOnUiThread(new Runnable(){ public void run() { _listener.callCompleted(str); } }); } catch(Exception e){ e.printStackTrace(); } } } catch (UnknownHostException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
//in onCreate of your main actiivty //remove the call to MessageConsumer TcpServiceHandler handler=new TcpServiceHandler(this,this); Thread th=new Thread(handler); th.start();

import java.net.*; import java.io.*; public class TCPSendServer implements Runnable{ public static final String SERVERIP = "192.168.62.23"; public static final int SERVERPORT = 1200; public void run() { try { System.out.println("S: Connecting..."); ServerSocket serverSocket = new ServerSocket(SERVERPORT); //String msg = "<MSG><N>shiftDirection</N><V>1</V></MSG>"; String msg1 = "<MSG><N>shiftDirection</N><V>0</V></MSG>"; String msg2 = "SD<!N><V>0<!V><!MSG>"; int ktr=1; Socket client = serverSocket.accept(); while (true) { try { PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(client.getOutputStream())),true); if(ktr==1){ System.out.println("S: Sending: '" + msg2+ "'"); out.println(msg2); ktr++; } else{ System.out.println("S: Sending: '" + msg1+ "'"); out.println(msg1); ktr=1; } out.flush(); System.out.println("S: Sent."); System.out.println("S: Done."); Thread.sleep(1000); } catch(Exception e) { System.out.println("S: Error"); e.printStackTrace(); } //finally { // client.close(); //} } } catch (Exception e) { System.out.println("S: First try error"); e.printStackTrace(); } } public static void main (String a[]) { Thread desktopServerThread = new Thread(new TCPSendServer()); desktopServerThread.start(); } }

Hi Swastik,

I tried the above without the changed SendServer. It helped a lot. Thank you.

The server is the app in the car PC which gets messages with updated values every 100 milliseconds and sends those messages to the Android app.

So when I receive more than one message and I have to display an image or a text info for each message received, it hangs. I am trying to incorporate some things like this: after a particular message is received, I have to kind of freeze all other execution so that I can show some image or info related to the received message and after that resume all the execution.

Thanks a lot again.

Madhu Nandan

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Swastik Dey wrote:I hope this time it solves your purpose
public class TcpServiceHandler implements Runnable{ TCPListener _listener; private Activity _act; public TcpServiceHandler(TCPListener listener,Activity act){ _listener=listener; _act=act; } public synchronized void run() { // TODO Auto-generated method stub //if(socket==null){ try { InetAddress serverAddr = InetAddress.getByName("192.168.1.123"); Socket socket= new Socket(serverAddr, 1200); // while(true){ try { BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream())); final String str = in.readLine(); this._act.runOnUiThread(new Runnable(){ public void run() { _listener.callCompleted(str); } }); } catch(Exception e){ e.printStackTrace(); } } } catch (UnknownHostException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
//in onCreate of your main actiivty //remove the call to MessageConsumer TcpServiceHandler handler=new TcpServiceHandler(this,this); Thread th=new Thread(handler); th.start();

import java.net.*; import java.io.*; public class TCPSendServer implements Runnable{ public static final String SERVERIP = "192.168.62.23"; public static final int SERVERPORT = 1200; public void run() { try { System.out.println("S: Connecting..."); ServerSocket serverSocket = new ServerSocket(SERVERPORT); //String msg = "<MSG><N>shiftDirection</N><V>1</V></MSG>"; String msg1 = "<MSG><N>shiftDirection</N><V>0</V></MSG>"; String msg2 = "SD<!N><V>0<!V><!MSG>"; int ktr=1; Socket client = serverSocket.accept(); while (true) { try { PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(client.getOutputStream())),true); if(ktr==1){ System.out.println("S: Sending: '" + msg2+ "'"); out.println(msg2); ktr++; } else{ System.out.println("S: Sending: '" + msg1+ "'"); out.println(msg1); ktr=1; } out.flush(); System.out.println("S: Sent."); System.out.println("S: Done."); Thread.sleep(1000); } catch(Exception e) { System.out.println("S: Error"); e.printStackTrace(); } //finally { // client.close(); //} } } catch (Exception e) { System.out.println("S: First try error"); e.printStackTrace(); } } public static void main (String a[]) { Thread desktopServerThread = new Thread(new TCPSendServer()); desktopServerThread.start(); } }

Hi Swastik,

When I run the application (with the above code), how can I stop the app? Once I start it, the app keeps running all the time, phone kind of hangs and is not possible to stop it. Only way is I have to keep pressing "Home" button on phone many times and then got o Settings-App-Manage app and stop this app by pressing "Force Stop". Could you suggest a way out of this?

Regards,
Madhu

Madhu Nandan

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Swastik Dey wrote:I hope this time it solves your purpose
public class TcpServiceHandler implements Runnable{ TCPListener _listener; private Activity _act; public TcpServiceHandler(TCPListener listener,Activity act){ _listener=listener; _act=act; } public synchronized void run() { // TODO Auto-generated method stub //if(socket==null){ try { InetAddress serverAddr = InetAddress.getByName("192.168.1.123"); Socket socket= new Socket(serverAddr, 1200); // while(true){ try { BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream())); final String str = in.readLine(); this._act.runOnUiThread(new Runnable(){ public void run() { _listener.callCompleted(str); } }); } catch(Exception e){ e.printStackTrace(); } } } catch (UnknownHostException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
//in onCreate of your main actiivty //remove the call to MessageConsumer TcpServiceHandler handler=new TcpServiceHandler(this,this); Thread th=new Thread(handler); th.start();

import java.net.*; import java.io.*; public class TCPSendServer implements Runnable{ public static final String SERVERIP = "192.168.62.23"; public static final int SERVERPORT = 1200; public void run() { try { System.out.println("S: Connecting..."); ServerSocket serverSocket = new ServerSocket(SERVERPORT); //String msg = "<MSG><N>shiftDirection</N><V>1</V></MSG>"; String msg1 = "<MSG><N>shiftDirection</N><V>0</V></MSG>"; String msg2 = "SD<!N><V>0<!V><!MSG>"; int ktr=1; Socket client = serverSocket.accept(); while (true) { try { PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(client.getOutputStream())),true); if(ktr==1){ System.out.println("S: Sending: '" + msg2+ "'"); out.println(msg2); ktr++; } else{ System.out.println("S: Sending: '" + msg1+ "'"); out.println(msg1); ktr=1; } out.flush(); System.out.println("S: Sent."); System.out.println("S: Done."); Thread.sleep(1000); } catch(Exception e) { System.out.println("S: Error"); e.printStackTrace(); } //finally { // client.close(); //} } } catch (Exception e) { System.out.println("S: First try error"); e.printStackTrace(); } } public static void main (String a[]) { Thread desktopServerThread = new Thread(new TCPSendServer()); desktopServerThread.start(); } }

Hi Swastik,

When I used this code for client, it works alright. The server was another Java app running in Eclipse. When I tried to receive message from my colleague's app (developed in Rhapsody and I think C++), I receive the message only after his app is closed and not while his app is running and sending messages. Do you have any idea why this happens?

My situation: I run the client code on Android phone (HTC Desire). If the server is a java app running in Eclipse, then I can receive data sent by this server on my Android phone. When I try to receive data from another app (say abc, which can be considered to be acting as server), then I can connect to the app but cannot receive any data. Instead of connecting the real phone to abc, if I try connecting the client from emulator, then I can receive the data sent from abc only after abc is closed, not when it is running and sending data. Real phone & abc doesn't work-connection is established but no data

The java server is like this:

public class TCPSendServer implements Runnable{
	public static final String SERVERIP = "192.168.178.24";
    public static final int SERVERPORT = 1200;
    //static Category cat = Category.getInstance(TCPSendServer.class.getName());
    //cat.debug("Start of main()");
         
    public void run() {
         try {
        	 System.out.println("S: Connecting...");             
             ServerSocket serverSocket = new ServerSocket(SERVERPORT);
             String msg = "<MSG><N>shiftDirection</N><V>1</V></MSG>";
             String msg1 = "<MSG><N>vehicleSpeed</N><V>120</V></MSG>";
             String msg2 = "SD<!N><V>0<!V><!MSG>";
             
             //while (true)	{
            	 Socket client = serverSocket.accept();
            	 
            	  try {
            		  System.out.println("S: Sending: '" + msg + "'");
     		    	  PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(client.getOutputStream())),true);     		    	 
     		    	  Thread.sleep (5000);
     		    	  out.println(msg);
     		    	  Thread.sleep (5000);
     		    	  //out.println(msg2);
     		    	  Thread.sleep (5000);
    		    	  out.println(msg1);
     		    	  //out.flush();
     		    	  System.out.println("S: Sent.");
     		    	  System.out.println("S: Done.");
                    } catch(Exception e) {
                        System.out.println("S: Error");
                        e.printStackTrace();
                    } //finally {
                      //	client.close();                        
                    //}  
             //}
         } catch (Exception e) {
             System.out.println("S: First try error");
             e.printStackTrace();
         }
    }
    
    public static void main (String a[]) {
    	Thread desktopServerThread = new Thread(new TCPSendServer());
    	desktopServerThread.start();
    }
}

With a little knowledge, a cast iron skillet is non-stick and lasts a lifetime.