String getLabel() {
      // Lazily concat the label.
      if (label == null) {
        label = flattener.flatten(timeMillis, logLevel, tag, msg).toString();
      }
      return label;
    }
Get the label, with formatted time, log level and tag.
xlog-sample/src/main/java/com/elvishew/xlogsample/RecyclerViewPrinter.java