FATAL EXCEPTION:main error occurs

Socket socket; // Create socket

Buffered Reader in; //Read data from the server.
PrintWriter out; //Send data to the server.
EditText input; //xml element
Button button; //xml element
TextView output; //xml element
String data; //Socket data storage

@Override
protected void on Create(Bundle saved InstanceState) { //Setting initialization at app startup
    super.onCreate(savedInstanceState);
    setContentView (R.layout.socket_lay); //Load Layout

    input = (EditText) findViewById(R.id.input); // character input (edit text)
    button = (Button) findViewById(R.id.Button); // Send button
    output = (TextView) findViewById(R.id.output); // Received data

    Button.setOnClickListener() { //The part you send to button
        When the public void on Click(View) { // button is clicked, it outputs data to the socket.

            String data = input.getText().toString(); //Receive the characters in the character input box in String form and store them in the data
            Log.w("NETWORK", " " + data);
            If (data!=null) { //if no data is entered
                out.println(data); //data is transformed into a stream form and transmitted.  The transformation is contained in the thread.
            }
        }
    });

    Create Threadworker = new Thread() { //worker as Thread
        public void run() { // thread execution syntax

            Create a try { // socket and connect the input/output strip to the socket.
                socket = new socket ("192.168.4.1", 8080); //Socket connection
                out = new PrintWriter(socket.getOutputStream(),true); //Transfer data to stream form when transmitting.
                in = new BufferedReader(new InputStreamReader(
                        socket.getInputStream()));//Accept stream when receiving data.

            } catch (IOException) { //Additional Description https://code.i-harness.com/ko-kr/q/c9a994
                e.printStackTrace();
                Toast.makeText (com.example.jbts201604.socket_37.socket.this,"ConnectionError", Toast.LENGTH_SHORT).show();
            }


            try {
                while (true) {
                    Data = in.readLine(); // read data received in String format and stored in data

                    output.post(new Runnable() {
                        public void run() {
                            Output.setText(data); //print messages sent by the server in the character output box.
                        }
                    });
                }
            } } catch (Exception e) {
                Toast.makeText (com.example.jbts201604.socket_37.socket.this",Toast.LENGTH_SHORT).show();

            }
        }
    };
    Run at worker.start(); //onResume().
}

@Override
protected void onStop() { //When the app is closed
    super.onStop();
    try {
        socket.close(); // Close the socket.
    } } catch (IOException e) {
        e.printStackTrace();
    }
}