'java.net.Socket java.net.ServerSocket.accept()' on a null object reference

Question

Server Socket throwing this error and app completely crashes. I called this thread in my onCreate() method . When activity is running for the first time it is good but after finishing and get back to this activity is giving below error.

'java.net.Socket java.net.ServerSocket.accept()' on a null object reference

 private class ClientConnectionThread implements Runnable {
        ServerSocket serversocket;

        public ClientConnectionThread(){
            try{
                serversocket = new ServerSocket(5005);
                serversocket.setReceiveBufferSize(1024*1024);
                Log.v("BoardCastRunning","BoardCast Server Waiting");
            }catch (IOException ex){
                Log.v("BoardCastError",ex.toString());
            }


        }

        @Override
        public void run() {

            while(true){
                try{

                    streamClientSocket = serversocket.accept();
                    Log.v("BoardCast","New Connection");
                    videoBroadcastSockets.add(streamClientSocket);
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            Utils.shortToast(context,
                                    "Client connected from: "
                                            + streamClientSocket.getInetAddress().getHostAddress()
                                            + " " + streamClientSocket.getPort());


                        }
                    });
                }
                catch(IOException ex){
                    Log.v("BoardCastError",ex.toString());
                }


            }
        }
    }

You forgot the word NullPointerException. Why didnt you mention the complete message? — greenapps, May 06 '17 at 18:11
Because you are probably getting NetworkOnMainThreadException. — WalterM, May 06 '17 at 19:50

score -1 · Accepted Answer · answered May 07 '17 at 04:53

I find the error and edit my code as below now it's working fine & perfectly.

  private class ClientConnectionThread implements Runnable {
        ServerSocket serversocket;

        public ClientConnectionThread(){
            try{
                serversocket = new ServerSocket(5005);
                serversocket.setReceiveBufferSize(1024*1024);
                Log.v("BoardCastRunning","BoardCast Server Waiting");
            }catch (IOException ex){
                Log.v("BoardCastError",ex.toString());
            }


        }

        @Override
        public void run() {

            while(true){
                try{
                    if(serversocket!=null){
                        if(!serversocket.isClosed()){
                            streamClientSocket = serversocket.accept();
                            Log.v("BoardCast","New Connection");
                            if(streamClientSocket!=null){
                                videoBroadcastSockets.add(streamClientSocket);
                                runOnUiThread(new Runnable() {
                                    @Override
                                    public void run() {
                                        Utils.shortToast(context,
                                                "Client connected from: "
                                                        + streamClientSocket.getInetAddress().getHostAddress()
                                                        + " " + streamClientSocket.getPort());


                                    }
                                });
                            }

                        }
                    }


                }
                catch(IOException ex){
                    Log.v("BoardCastError",ex.toString());
                }


            }
        }
    }

You fixed it how? You have to explain. If `serverSocket` is null or closed you are looping endlessly and pointlessly. Not good code. — user207421, May 07 '17 at 05:49

'java.net.Socket java.net.ServerSocket.accept()' on a null object reference

1 Answers1