在 Driver 类 conf.getstrings() 方法中获取 Null 指针异常。这个驱动程序类是从我的自定义网站调用的。
下面是Driver类的详细信息
@SuppressWarnings("unchecked")
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException
{
Configuration conf = new Configuration();
//conf.set("fs.default.name", "hdfs://localhost:54310");
//conf.set("mapred.job.tracker", "localhost:54311");
//conf.set("mapred.jar","/home/htcuser/Desktop/ResumeLatest.jar");
Job job = new Job(conf, "ResumeSearchClass");
job.setJarByClass(HelloForm.class);
job.setJobName("ResumeParse");
job.setInputFormatClass(FileInputFormat.class);
FileInputFormat.addInputPath(job, new Path("hdfs://localhost:54310/usr/ResumeDirectory"));
job.setMapperClass(ResumeMapper.class);
job.setReducerClass(ResumeReducer.class);
job.setMapOutputKeyClass(IntWritable.class);
job.setSortComparatorClass(ReverseComparator.class);
job.setMapOutputValueClass(Text.class);
job.setOutputKeyClass(IntWritable.class);
job.setOutputValueClass(Text.class);
job.setOutputFormatClass(FileOutPutFormat.class);
FileOutputFormat.setOutputPath(job, new Path("hdfs://localhost:54310/usr/output" + System.currentTimeMillis()));
long start = System.currentTimeMillis();
var = job.waitForCompletion(true) ? 0 : 1;
下面两行代码获取NULL指针异常
String[] keytextarray=conf.getStrings("Keytext");
for(int i=0;i<keytextarray.length;i++) //GETTING NULL POINTER EXCEPTION HERE IN keytextarray.length
{
//some code here
}
if(var==0)
{
RequestDispatcher dispatcher = request.getRequestDispatcher("/Result.jsp");
dispatcher.forward(request, response);
long finish= System.currentTimeMillis();
System.out.println("Time Taken "+(finish-start));
}
}
我从上面的 Drives 类方法中删除了一些不需要的代码...
下面是 RecordWriter 类,我在 Write() 方法中使用 conf.setstrings() 来设置值
下面是 RecordWriter 类的详细信息
public class RecordWrite extends org.apache.hadoop.mapreduce.RecordWriter<IntWritable, Text> {
TaskAttemptContext context1;
Configuration conf;
public RecordWrite(DataOutputStream output, TaskAttemptContext context)
{
out = output;
conf = context.getConfiguration();
HelloForm.context1=context;
try {
out.writeBytes("result:\n");
out.writeBytes("Name:\t\t\t\tExperience\t\t\t\t\tPriority\tPriorityCount\n");
} catch (IOException e) {
e.printStackTrace();
}
}
public RecordWrite() {
// TODO Auto-generated constructor stub
}
@Override
public void close(TaskAttemptContext context) throws IOException,
InterruptedException
{
out.close();
}
int z=0;
@Override
public void write(IntWritable value,Text key) throws IOException,
InterruptedException
{
conf.setStrings("Keytext", key1string); //setting values here
conf.setStrings("valtext", valuestring);
String[] keytext=key.toString().split(Pattern.quote("^"));
//some code here
}
}`
`我怀疑这个空指针异常发生是因为我在作业完成后调用了 conf.getstrings() 方法 (job.waitForCompletion(true))。请帮助解决这个问题。
如果上述代码不是将值从 recordwriter() 方法传递到驱动程序类的正确方法。请告诉我如何将值从 recordwriter() 传递到驱动程序类。
我尝试过将 RecordWriter() 中的值设置为自定义静态类的选项,如果我在集群中运行代码,则从 Driverclass 中的静态类访问该对象再次返回 Null 异常。
最佳答案
如果您在 Job 类中有 key1staring 和 valuestirng 的值,请尝试在作业类本身中设置它们,而不是 RecordWriter.write() 方法。
关于java - getstrings方法hadoop中的空指针异常,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/30757327/