.. highlight:: java

Logging
=======

The `Logging <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Logging.html>`_ class interacts with the logger, which stores sensor data to the on-board flash memory.

Starting the Logger
-------------------

To start logging, call the `startLogging <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Logging.html#startLogging()>`_ method.  If you wish to overwrite existing entries, use the `overloaded <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Logging.html#startLogging(boolean)>`_ method instead.

::

    import com.mbientlab.metawear.module.Logging;
    
    final Logging logModule= mwBoard.getModule(Logging.class);
    
    // start logging, if log is full, no new data will be added
    logModule.startLogging();
    
    // start logging, if log is full, overrite existing data
    logModule.startLogging(true);

Downloading Data
----------------

When you are ready to retrieve the data, call the `downloadLog <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Logging.html#downloadLog(float,%20com.mbientlab.metawear.module.Logging.DownloadHandler)>`_ method.  The method takes in a `DownloadHandler <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Logging.DownloadHandler.html>`_, which handles notifications from the logger, and how often to send progress updates to the user.  It also returns an AsyncOperation object that contains the number of entries to download.

::

    // Start downloading the log
    // All MessageHandlers passed to setLogMessageHandler will be called
    logModule.downloadLog(new Logging.DownloadHandler() {
        @Override
        public void onProgressUpdate(int nEntriesLeft, int totalEntries) {
            Log.i("MainActivity", String.format("Progress= %d / %d", nEntriesLeft, 
                    totalEntries));
        }
    });