title: Difference between Reading a characteristic and setting up notifications
body: <p>Hi I am working on a Bluetooth low energy in my android app 
  I am able to read the characteristics whenever I call my <code>readCharacter()</code> in app 
  but I want to enable a notification such that when ever there is data available I can read. 
  Currently I am using the method below.</p>
  
  <pre><code>private byte[] readCharacteristic(){
   if(!isReadEnabled){
          enableTXNotification();
          isReadEnabled = true;
      }
  
      byte[] arr = new byte[CHUCK_SIZE];
      BluetoothGattService RxService = mBluetoothGatt.getService(RX_SERVICE_UUID);
      if(RxService == null){
          broadcastUpdate(BLUETOOTH_EVENT_SERVICES_NOT_SUPPORTED);
          return arr;
      }
      BluetoothGattCharacteristic TxChar = RxService.getCharacteristic(TX_CHAR_UUID);
      if(TxChar == null){
          broadcastUpdate(BLUETOOTH_EVENT_SERVICES_NOT_SUPPORTED);
          return arr;
      }
      arr = TxChar.getValue();
      Log.d(TAG,Arrays.toString(arr));
      return arr;
  }
  </code></pre>
  
  <p>And this is my <code>enableTXNotification()</code>:</p>
  
  <pre><code>private void enableTXNotification(){
      if (mBluetoothGatt == null) {
          broadcastUpdate(BLUETOOTH_EVENT_SERVICES_NOT_SUPPORTED);
          return;
      }
  
      BluetoothGattService RxService = mBluetoothGatt.getService(RX_SERVICE_UUID);
      if (RxService == null) {
          broadcastUpdate(BLUETOOTH_EVENT_SERVICES_NOT_SUPPORTED);
          return;
      }
      BluetoothGattCharacteristic TxChar = RxService.getCharacteristic(TX_CHAR_UUID);
      if (TxChar == null) {
          broadcastUpdate(BLUETOOTH_EVENT_SERVICES_NOT_SUPPORTED);
          return;
      }
      mBluetoothGatt.setCharacteristicNotification(TxChar,true);
      BluetoothGattDescriptor descriptor = TxChar.getDescriptor(CCCD);
      descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
      mBluetoothGatt.writeDescriptor(descriptor);
  }
  </code></pre>
  
  <h3> So my question is what is the difference between Enabling notification and Reading characteristic?</h3>
  
  <h3>How can I get notification whenever data is available</h3>