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<Text,Connection> {
@Override
public RecordReader<Text,Connection> 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$ConnectionInputFormat.<init>() at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:115) at org.apache.hadoop.mapred.JobClient.writeNewSplits(JobClient.java:882) at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:779) at org.apache.hadoop.mapreduce.Job.submit(Job.java:432) at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:447) at testingground.TestInputJob.run(TestInputJob.java:141) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79) at testingground.TestInputJob.main(TestInputJob.java:156) Caused by: java.lang.NoSuchMethodException: testingground.TestInputJob$ConnectionInputFormat.<init>() 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<Text,Connection> {
public ConnectionInputFormat() {
System.out.println("NetflowInputFormat Constructor");
}
@Override
public RecordReader<Text,InterruptedException {
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<Text,Connection> {
public ConnectionInputFormat() {
System.out.println("NetflowInputFormat Constructor");
}
public ConnectionInputFormat(Object... o) {
System.out.println("NetflowInputFormat Constructor");
}
@Override
public RecordReader<Text,InterruptedException {
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.
全电流源：http://pastebin.com/2XyW5ZSS
解决方法
您的ConnectionInputFormat类应该是静态的.非静态嵌套类在每个构造函数中都添加了隐含的“this”.因此,除非将类声明为static,否则no-arg构造函数实际上具有不可见的参数.