目前我正在尝试学习MapReduce中的二次排序，但是在运行Map程序时出现了一个空指针异常错误。我使用这个链接，但在运行代码时，我得到了错误。这是我的呼叫堆栈。
2018年6月16日13:34:53 info mapreduce.job:任务id:尝试\u 1466235357420 \u 0007 \u m \u 0000000，状态：失败错误：secondartsort.secondarysortsample1.secondarysortmapper.map（secondarysortmapper）处的java.lang.nullpointerexception。java:22)在secondarySort.secondarysortsample1.secondarysortmapper.map（secondarysortmapper。java:1)在org.apache.hadoop.mapreduce.mapper.run（mapper。java:145)在org.apache.hadoop.mapred.maptask.runnewmapper（maptask。java:784)在org.apache.hadoop.mapred.maptask.run（maptask。java:341)在org.apache.hadoop.mapred.yarnchild$2.run（yarnchild。java:163)位于javax.security.auth.subject.doas（subject）的java.security.accesscontroller.doprivileged（本机方法）。java:415)
我的Map程序代码是：

public class SecondarySortMapper  extends Mapper<LongWritable , Text, CustomTextInt, IntWritable> {

    private CustomTextInt nameDepname;
    private Text name;
    private Text departmentName;
    private IntWritable sal;
    public void map (LongWritable key , Text value , Context context) throws IOException , InterruptedException{

        String[] line = value.toString().split(",");

        //String depName = line[3];
        String Fullname =line[2]+line[1];
        name.set(Fullname);
        departmentName.set(line[3]);
        nameDepname.set(name,departmentName);
        sal.set(Integer.parseInt(line[4]));
        context.write(nameDepname, sal);    
    }
}

数据文件为：

1,kumar,sunil,enginering,2200
2,mishra,sunil,enginering,1200
3,arora,karan,mech,1200
4,sharma,vivek,physics,2300
5,koushik,vivek,physics,1350
6,sindhu,armaan,math,2310
7,arora,armaan,math,500
8,yadav,pooja,mech,1800
9,kuthi,pooja,math,1600
10,arora,sunil,physics,1450
11,mishra,karan,enginering,3400
12,chandra,manish,physics,2300

善意的建议
谢谢斯普拉德