Question

目前我正在尝试在map map中学习Secondary Sort，但在运行mapper时遇到空指针异常错误。我正在使用此link 但是在运行代码时我得到了错误。这是我的callStack。

16/06/18 13:34:53 INFO mapreduce.Job：任务ID：attempt_1466235357420_0007_m_000000_0，状态：未通过错误：java.lang.NullPointerException 在SecondartSort.SecondarySortSample1.SecondarySortMapper.map（SecondarySortMapper.java:22）在SecondartSort.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） at java.security.AccessController.doPrivileged（Native Method）在javax.security.auth.Subject.doAs（Subject.java:415）

我的映射器代码是：

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);    
    }
}

和数据文件是：

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

由于 sPradeep

Answer 1

您实际上并未创建任何类变量。这些都将是未初始化的：

private CustomTextInt nameDepname;
private Text name;
private Text departmentName;
private IntWritable sal;

例如name应如下所示：

private Text name = new Text();

获取nullPointer异常

1 个答案: