自定义MapReduce输入格式 - 找不到构造函数
I'm writing a custom InputFormat for Hadoop 0.20.2 and am running into a NoSuchMethodException I can't get rid of. I started with:
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();
}
}
I got this error when running:
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
After getting the error inititially and researching online, I thought it might be that I didn't have a zero-argument constructor, so I added one:
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, Connection> createRecordReader(InputSplit split, TaskAttemptContext context) throws IOException, InterruptedException {
return new ConnectionRecordReader();
}
}
That didn't work either, so I added a second constructor that took in any number of objects:
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, Connection> createRecordReader(InputSplit split, TaskAttemptContext context) throws IOException, InterruptedException {
return new ConnectionRecordReader();
}
}
Still getting the same error, and have been so far unsuccessful in finding a solution.
仍然得到相同的错误,并且到目前为止找不到解决方案是不成功的。
Full current source: http://pastebin.com/2XyW5ZSS
全电流源:http://pastebin.com/2XyW5ZSS
1 个解决方案
#1
7
Your ConnectionInputFormat class should be static. Non-static nested classes have an implied 'this' added to every constructor. Thus, your no-arg constructor actually has an invisible argument unless the class is declared static.
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。