我正在为Hadoop 0.20.2编写一个自定义的InputFormat,并且遇到NoSuchMethodException我无法摆脱.我开始时：

public class ConnectionInputFormat extends FileInputFormat {

@Override

public RecordReader createRecordReader(InputSplit split,TaskAttemptContext context) throws IOException,InterruptedException {

return new ConnectionRecordReader();

}

}

运行时出现此错误：

Exception in thread "main" java.lang.RuntimeException: java.lang.NoSuchMethodException: testingground.TestInputJob$ConnectionInputFormat.()

at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:115)

at org.apache.hadoop.mapred.JobClient.writeNewSplits(JobClient.java:882)

at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:779)

at org.apache.hadoop.mapreduce.Job.submit(Job.java:432)

at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:447)

at testingground.TestInputJob.run(TestInputJob.java:141)

at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)

at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)

at testingground.TestInputJob.main(TestInputJob.java:156)

Caused by: java.lang.NoSuchMethodException: testingground.TestInputJob$ConnectionInputFormat.()

at java.lang.Class.getConstructor0(Class.java:2706)

at java.lang.Class.getDeclaredConstructor(Class.java:1985)

at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:109)

... 8 more

Java Result: 1

在初始化错误并在线研究之后,我认为可能是因为我没有零参数构造函数,所以我添加了一个：

public class ConnectionInputFormat extends FileInputFormat {

public ConnectionInputFormat() {

System.out.println("NetflowInputFormat Constructor");

}

@Override

public RecordReader

return new ConnectionRecordReader();

}

}

这也没用,所以我添加了第二个构造函数,它接受了任意数量的对象：

public class ConnectionInputFormat extends FileInputFormat {

public ConnectionInputFormat() {

System.out.println("NetflowInputFormat Constructor");

}

public ConnectionInputFormat(Object... o) {

System.out.println("NetflowInputFormat Constructor");

}

@Override

public RecordReader

return new ConnectionRecordReader();

}

}

仍然得到相同的错误,并且迄今为止找不到解决方案是不成功的.