Cannot compile WordCount.java

wi16b087 — Fri, 16 Sep 2022 14:14:54 GMT

Hi, I'm following Douglas Eadline's tutorial http://www.informit.com/store/hadoop-and-spark-fundamentals-livelessons-9780134770864 and try to compile the WordCount example, but I fail. Eadline suggests to comile it with hadoop-core.jar, which was renamed in newer versions as I understand.

I tried with javac -classpath /usr/hdp/current/hadoop-mapreduce-client/hadoop-mapreduce-client-core.jar -d wordcount_classes WordCount.java but I still get a load of errors. Any suggestions? Where can I find the correct jar?

WordCount.java:27: error: package org.apache.hadoop.conf does not exist

import org.apache.hadoop.conf.Configuration;

WordCount.java:28: error: package org.apache.hadoop.conf does not exist

import org.apache.hadoop.conf.Configured;

WordCount.java:29: error: package org.apache.hadoop.fs does not exist

import org.apache.hadoop.fs.Path;

WordCount.java:30: error: package org.apache.hadoop.io does not exist

import org.apache.hadoop.io.IntWritable;

WordCount.java:31: error: package org.apache.hadoop.io does not exist

import org.apache.hadoop.io.LongWritable;

WordCount.java:32: error: package org.apache.hadoop.io does not exist

import org.apache.hadoop.io.Text;

WordCount.java:42: error: package org.apache.hadoop.util does not exist

import org.apache.hadoop.util.Tool;

WordCount.java:43: error: package org.apache.hadoop.util does not exist

import org.apache.hadoop.util.ToolRunner;

WordCount.java:54: error: cannot find symbol

public class WordCount extends Configured implements Tool {

symbol: class Configured

WordCount.java:54: error: cannot find symbol

public class WordCount extends Configured implements Tool {

symbol: class Tool

WordCount.java:61: error: cannot access Closeable

public static class MapClass extends MapReduceBase

class file for org.apache.hadoop.io.Closeable not found

WordCount.java:64: error: cannot find symbol

private final static IntWritable one = new IntWritable(1);

symbol: class IntWritable

location: class MapClass

WordCount.java:65: error: cannot find symbol

private Text word = new Text();

symbol: class Text

location: class MapClass

WordCount.java:67: error: cannot find symbol

public void map(LongWritable key, Text value,

symbol: class LongWritable

location: class MapClass

WordCount.java:67: error: cannot find symbol

public void map(LongWritable key, Text value,

symbol: class Text

location: class MapClass

WordCount.java:68: error: cannot find symbol

OutputCollector<Text, IntWritable> output,

symbol: class Text

location: class MapClass

WordCount.java:68: error: cannot find symbol

OutputCollector<Text, IntWritable> output,

symbol: class IntWritable

location: class MapClass

WordCount.java:83: error: cannot find symbol

implements Reducer<Text, IntWritable, Text, IntWritable> {

symbol: class Text

location: class WordCount

WordCount.java:83: error: cannot find symbol

implements Reducer<Text, IntWritable, Text, IntWritable> {

symbol: class IntWritable

location: class WordCount

WordCount.java:83: error: cannot find symbol

implements Reducer<Text, IntWritable, Text, IntWritable> {

symbol: class Text

location: class WordCount

WordCount.java:83: error: cannot find symbol

implements Reducer<Text, IntWritable, Text, IntWritable> {

symbol: class IntWritable

location: class WordCount

WordCount.java:85: error: cannot find symbol

public void reduce(Text key, Iterator<IntWritable> values,

symbol: class Text

location: class Reduce

WordCount.java:85: error: cannot find symbol

public void reduce(Text key, Iterator<IntWritable> values,

symbol: class IntWritable

location: class Reduce

WordCount.java:86: error: cannot find symbol

OutputCollector<Text, IntWritable> output,

symbol: class Text

location: class Reduce

WordCount.java:86: error: cannot find symbol

OutputCollector<Text, IntWritable> output,

symbol: class IntWritable

location: class Reduce

Re: Cannot compile WordCount.java

jsensharma — Sun, 24 Mar 2019 02:54:48 GMT

@Alessandro Volcich

The hadoop command line utility also provides an option to get the correct classpath produced something like following which you can use:

Example:

# export CLASSPATH=`hadoop classpath`:.:

# echo $CLASSPATH
# javac -d wordcount_classes WordCount.java

Re: Cannot compile WordCount.java

wi16b087 — Sun, 24 Mar 2019 19:19:46 GMT

Thank you, indeed it worked with

javac -cp `hadoop classpath` -d wordcount_classes WordCount.java

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Cannot compile WordCount.java

Re: Cannot compile WordCount.java

Re: Cannot compile WordCount.java