private boolean hasValidClientPortInList(int index) {
    return (clientPortList.size() > index && clientPortList.get(index) > 0);
  }
Check whether the client port in a specific position of the client port list is valid.
@param index the specified position
hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/MiniZooKeeperCluster.java