public void arrowUp() {
    if (currentPosition > 0) {
      currentPosition -= 1;
      if (pageSize > 0) {
        keepConsistent();
      }
    }
  }
Utility class for paging for the metrics.
hbase-hbtop/src/main/java/org/apache/hadoop/hbase/hbtop/screen/top/Paging.java