CTex listings宏包出错undefined control sequence,换成verbatim解决问题

在CTex欲显示源代码,首先使用listings宏包,

\usepackage{listings}

......

然后

\begin{lstlisting}
public static class MapClass extends MapReduceBase
    implements Mapper<LongWritable, Text, Text, IntWritable> {

    private final static IntWritable one = new IntWritable(1);
    private Text word = new Text();

    public void map(LongWritable key, Text value,
                    OutputCollector<Text, IntWritable> output,
                    Reporter reporter) throws IOException {
      String line = value.toString();
      StringTokenizer itr = new StringTokenizer(line);

    }
  }
\end{lstlisting}

接着PDFLatex,但是总是提示出错, undefined control sequence,找了很久没发现是什么问题.

将其中的代码部分改为一段C的hello world代码,则编译通过.

始终不得其解.

最后解决办法是改用verbatim宏包,

将上述代码改为用\begin{verbatim} 和\end{verbatim}包围.

则顺利通过编译.