.. highlight:: java

Logging
=======
Mbientlab boards are equipped with flash memory that can store data if there is no connection with an Android device.  While the ``RouteComponent`` 
directs data to the logger, the `Logging <https://mbientlab.com/docs/metawear/android/3/com/mbientlab/metawear/module/Logging.html>`_ interface provides 
the functions for controlling and configuring the logger.

::

    import com.mbientlab.metawear.module.Logging;

    final Logging logging = board.getModule(Logging.class);

Start the Logger
----------------
To start logging, call the `start <https://mbientlab.com/docs/metawear/android/3/com/mbientlab/metawear/module/Logging.html#start-boolean->`_ method.  
If you wish to overwrite existing entries, pass ``true`` to the method.  When you are done logging, call 
`stop <https://mbientlab.com/docs/metawear/android/3/com/mbientlab/metawear/module/Logging.html#stop-->`_.  

::

    // start logging, if log is full, no new data will be added
    logging.start(false);
    
    // start logging, if log is full, overrite existing data
    logging.start(true);

    // stop the logger
    logging.stop();

Downloading Data
----------------
When you are ready to retrieve the data, call 
`downloadAsync <https://mbientlab.com/docs/metawear/android/3/com/mbientlab/metawear/module/Logging.html#downloadAsync-int-com.mbientlab.metawear.module.Logging.LogDownloadUpdateHandler->`_; 
the method returns a ``Task`` object that will be completed when the download finishes.  There are variants of ``downloadAsync`` that provide progress 
updates and error handing during the download.

::

    // download log data and send 100 progress updates during the download
    logging.downloadAsync(100, new Logging.LogDownloadUpdateHandler() {
        @Override
        public void receivedUpdate(long nEntriesLeft, long totalEntries) {
            Log.i("MainActivity", "Progress Update = " + nEntriesLeft + "/" + totalEntries);
        }
    }).continueWithTask(new Continuation<Void, Task<Void>>() {
        @Override
        public Task<Void> then(Task<Void> task) throws Exception {
            Log.i("MainActivity", "Download completed");
            return null;
        }
    });