Logger helper class. Makes the logger operations easy. Application needs to have no.nordicsemi.android.LOG permission to use this logger.

To use a logger you must first create a logger session. Log entries can be then appended to the session. Session has 2 parameters: a non-changeable key, which can be e.g. a device address and a name, which can be a human-readable device name. nRF Logger application use the key to group devices together. The logger session contains also the application name + optionally a profile name. To create the session invoke newSession method.

Log entries may not be deleted from the database except by removing the whole session.

Usage:

Adding log entry:

LogSession session = Logger.newSession(this, "DFU", deviceAddress, deviceName);
Logger.i(session, "Log session has been created");
...
String error = e.getMessage();
Logger.e(session, R.string.error_message, error);

where in strings.xml there is:

<string name="error_message">An error occurred: %s</string>

Getting session log entries:

final Cursor c = getContentResolver().query(session.getSessionEntriesUri(), new String[] {
       TIME,
       LEVEL,
       DATA }, null, null, TIME + " ASC");
try {
	while (c.moveToNext()) {
		final String data = c.getString(2 /* DATA */);
		...
   }
} finally {
	c.close();
}

You may use the following Uris to perform operations on the data set:

• no.nordicsemi.android.log/application - returns all applications that has created at least one log session
• no.nordicsemi.android.log/application/[APP_ID] - returns all sessions from given application
• no.nordicsemi.android.log/session - returns all sessions
• no.nordicsemi.android.log/session/[SESSION_ID] - returns the session with given id
• no.nordicsemi.android.log/session/[SESSION_ID]/log - returns the log entries from the session with given id
• no.nordicsemi.android.log/session/key/[KEY] - returns all sessions with given key
• no.nordicsemi.android.log/session/key/[KEY]/[NUMBER] - returns the session with given key and number. Numbers starts from 1 for every key.
• no.nordicsemi.android.log/session/key/[KEY]/[NUMBER]/log - returns the log entries from the session with given key and number

For every log session created on a new day for a single application (and optionally profile) a special "date" session is created. Its number is equal to 0 and key to "!date". To obtain a list of non-date sessions for a given application id sorted by date, key and time use:

@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
	long appId = args.getLong(APPLICATION_ID);

	Uri sessionsUri = LogContract.Session.createSessionsUri(appId);
	String selection = LogContract.Session.NUMBER + ">0";
	return new CursorLoader(this, sessionsUri,
		new String[] { NAME, CREATED_AT },
		selection, null, "date((" + CREATED_AT + " / 1000), 'unixepoch') DESC,
		" + KEY + " ASC,
		" + CREATED_AT + " DESC");
}