The default Locale is constructed statically at runtime for your application process from the system property settings, so it will represent the Locale selected on that device when the application was launched. Typically, this is fine, but it does mean that if the user changes their Locale in settings after your application process is running, the value of getDefaultLocale() probably will not be immediately updated.
If you need to trap events like this for some reason in your application, you might instead try obtaining the Locale available from the resource Configuration object, i.e.
Locale current = getResources().getConfiguration().locale;
You may find that this value is updated more quickly after a settings change if that is necessary for your application.