code: public File getRuntimeDir(String applicationName, boolean strict) {
  		File base = getRuntimeBase();
  		if (base == null) {
  			if (strict)
  				return null;
  			base = getCacheBase();
  		}
  		return createUserDir(base, applicationName);
  	}
docs: Get the application specific the directory relative to which user-specific non-essential
  runtime files and other file objects (such as sockets, named pipes, ...) should be stored.
  This directory is guaranteed to be cleared between system restarts.<p/>
  Since not all operating systems support a place fulfilling the last requirement, this
  method may return {@code null} when strict is {@code true}. If {@code strict} is
  {@code false}, this method returns never returns {@code null} but always a directory
  that is as close as possible.
  @param applicationName the name of the application
  @param strict detrmines whether to be strict at the requirements
  @return the application specific directory where to read and write non-essential files