Thanks. I went back and changed to WritableComparable instead of just Comparable. So, I added the readFields and write methods. I also took care of the typo in the constructor. :P
Now I am getting this error: 11/10/16 21:34:08 INFO mapred.JobClient: Task Id : attempt_201110162105_0002_m_000001_1, Status : FAILED java.lang.RuntimeException: java.lang.NoSuchMethodException: edu.bing.vfi5.KeyList.<init>() at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:115) at org.apache.hadoop.io.WritableComparator.newKey(WritableComparator.java:84) at org.apache.hadoop.io.WritableComparator.<init>(WritableComparator.java:70) at org.apache.hadoop.io.WritableComparator.get(WritableComparator.java:44) at org.apache.hadoop.mapred.JobConf.getOutputKeyComparator(JobConf.java:599) at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.<init>(MapTask.java:791) at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:350) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:307) at org.apache.hadoop.mapred.Child.main(Child.java:170) Caused by: java.lang.NoSuchMethodException: edu.bing.vfi5.KeyList.<init>() at java.lang.Class.getConstructor0(Class.java:2706) at java.lang.Class.getDeclaredConstructor(Class.java:1985) at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:109) Is it saying it can't find the constructor? On Sat, Oct 15, 2011 at 5:26 PM, Keith Thompson <[email protected]>wrote: > Hello, > I am trying to write my very first MapReduce code. When I try to run the > jar, I get this error: > > 11/10/15 17:17:30 INFO mapred.JobClient: Task Id : > attempt_201110151636_0003_m_000001_2, Status : FAILED > java.lang.ClassCastException: class edu.bing.vfi5.KeyList > at java.lang.Class.asSubclass(Class.java:3018) > at > org.apache.hadoop.mapred.JobConf.getOutputKeyComparator(JobConf.java:599) > at > org.apache.hadoop.mapred.MapTask$MapOutputBuffer.<init>(MapTask.java:791) > at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:350) > at org.apache.hadoop.mapred.MapTask.run(MapTask.java:307) > at org.apache.hadoop.mapred.Child.main(Child.java:170) > > I assume this means that it has something to do with my implementation of > comparable. KeyList is a class for a 3-tuple key. The code is listed > below. Any hints would be greatly appreciated as I am trying to understand > how comparable is supposed to work. Also, do I need to implement Writable > as well? If so, should this be code for how the output is written to a file > in HDFS? > > Thanks, > Keith > > package edu.bing.vfi5; > > public class KeyList implements Comparable<KeyList> { > > private int[] keys; > public KeyList(int i, int j, int k) { > keys = new int[3]; > keys[0] = i; > keys[1] = j; > keys[2] = k; > } > > @Override > public int compareTo(KeyList k) { > // TODO Auto-generated method stub > if(this.keys[0] == k.keys[0] && this.keys[1] == k.keys[1] && this.keys[2] > == k.keys[2]) > return 0; > else if((this.keys[0]>k.keys[0]) > ||(this.keys[0]==k.keys[0]&&this.keys[1]>k.keys[1]) > > ||(this.keys[0]==k.keys[0]&&this.keys[1]==k.keys[1]&&this.keys[2]>k.keys[2])) > return 1; > else > return -1; > } > } > > -- *Keith Thompson* Graduate Research Associate, Xerox Corporation SUNY Research Foundation Dept. of Systems Science and Industrial Engineering Binghamton University work: 585-422-6587
