[...]
 public class ActivityMain extends Activity implements WebSocket.WebSocketConnectionObserver {

   private volatile boolean isConnected = false;
   private WebSocketConnection wsConnection;
   private WebSocketOptions wsOptions;

   @Override
   protected void onCreate (Bundle savedInstanceState) {

     super.onCreate (savedInstanceState);
     setContentView (R.layout.activity_main);

     connectButton.setOnClickListener (new View.OnClickListener() {
       @Override
       public void onClick(View v) {
         wsConnect());
       }
     });

     cmdInput.setOnEditorActionListener (new EditText.OnEditorActionListener() {
       @Override
       public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
         if (actionId == EditorInfo.IME_ACTION_DONE) {
           wsSend();
           return true;
         }
         return false;
       }
     });
   }

   boolean wsConnect() {

     this.wsConnection = new WebSocketConnection();
     this.wsOptions = new WebSocketOptions();

     wsConnection.connect(wsURI, this, wsOptions);
   }

   void wsDisconnect() {
     wsConnection.disconnect();
   }

   void wsSend() {

     /* send message to the server */
     wsConnection.sendTextMessage(cmdInput.getText().toString());
     appendText(cmdOutput, "[CLIENT] " + cmdInput.getText().toString()  + "\n", Color.RED);
   }

   @Override
   public void onOpen() {
     this.isConnected = true;
   }

   @Override
   public void onClose (WebSocketCloseNotification code, String reason){
     this.isConnected = false;
   }

   @Override
   public void onTextMessage (String payload) {

     JSONObject jsonObj = new JSONObject(payload);

     if ((jsonObj.has(TAG_JSON_TYPE)) && (jsonObj.has(TAG_JSON_MSG))) {

       if (jsonObj.getString(TAG_JSON_TYPE).equals("notification")) {

         /* show notification */

       } else if (jsonObj.getString(TAG_JSON_TYPE).equals("standard")) {

         appendText(cmdOutput, "[SERVER]" + jsonObj.getString(TAG_JSON_MSG)+"\n",Color.RED);

       } else {

         Log.e (TAG_LOG, "Received invalid JSON from server");

       }
     }
   }

   @Override
   public void onRawTextMessage (byte[] payload) {
     Log.wtf (TAG_LOG, "We didn't expect 'RawTextMessage'");
   }

   @Override
   public void onBinaryMessage (byte[] payload) {
     Log.wtf (TAG_LOG, "We didn't expect 'BinaryMessage'");
   }
 [...]