从Cassandra ResultSet获取BigInteger属性

I'm trying to get the number of key value pairs in a Cassandra column family. Following is the code I used.

我正在尝试获取Cassandra列族中的键值对的数量。以下是我使用的代码。

PreparedStatement statement = client.session
            .prepare("select count(*) from corpus.word_usage");
ResultSet results = client.session.execute(statement.bind());   
Row row = results.one();
System.out.println(row.getVarint(0));

But when I ran this code, I'm getting following exception.

但是，当我运行此代码时，我得到了以下异常。

Exception in thread "main" com.datastax.driver.core.exceptions.InvalidTypeException: Column count is of type bigint
   at com.datastax.driver.core.ColumnDefinitions.checkType(ColumnDefinitions.java:291)
   at com.datastax.driver.core.ArrayBackedRow.getVarint(ArrayBackedRow.java:185)
   at SimpleClient.main(SimpleClient.java:57)

According to datastax documentation (http://www.datastax.com/drivers/java/2.0/com/datastax/driver/core/Row.html) getVarint should return a BigInteger. So why I am getting a exception here? What an I doing wrong?

根据datastax文档（http://www.datastax.com/drivers/java/2.0/com/datastax/driver/core/Row.html），getVarint应该返回一个BigInteger。那么为什么我在这里得到例外？我做错了什么？

2 个解决方案

#1

As specified here, you can get value as a long, instead.

如此处所指定的，您可以获得长期价值。

I couldn't test it but could you try this:

我无法测试它，但你可以试试这个：

PreparedStatement statement = client.session.prepare("select count(*) from corpus.word_usage");
ResultSet results = client.session.execute(statement.bind());   
Row row = results.one();
long expected = row.getLong("count");

#2

Following worked. I'm not sure why it is working though.

以下工作。我不确定它为什么会起作用。

row.getLong(0)

#1