在第一次读取时，映射reduce reduce在映射时失败

Question

当我尝试在简单输入上调试我的程序时，它在context.write(text, text)命令处失败。为什么会这样，我该如何解决？

public class TaskMapper extends Mapper<LongWritable, Text, Text, Text> {
    private Text country = new Text();
    private Text browser = new Text();
    public void map(LongWritable offset, Text line, Context context)

            throws IOException, InterruptedException {
        String[] words = line.toString().split(" ");

        country.set(words[1]);
        browser.set(words[0]);

        context.write(country, browser);
    }
}

输入文件是：

Chrome Israel
IE Israel
Firefox Denmark
Safari Denmark
Chrome Israel