【问题标题】:How compile WordCount.java in Hortonworks Sandbox?如何在 Hortonworks Sandbox 中编译 WordCount.java?
【发布时间】:2019-08-14 21:10:58
【问题描述】:

我正在学习教程并尝试在 Hortonworks Data Platform Sandbox 中运行 WordCount 示例。但是,当我尝试从命令行编译时出现错误并且无法构建它。

在终端中我输入 Java 编译命令:

$ javac WordCount.java

我没有编译和获取 .class 文件,而是收到以下错误:

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

我做错了什么?我使用当前版本的 Hortonworks Sandbox 2.6.1。 Hadoop 版本是 3.1.1

【问题讨论】:

    标签: hadoop hortonworks-sandbox


    【解决方案1】:

    您需要指定正确的类路径。在 Sandbox 中,您可以使用 hadoop 类路径信息。

    试试这个(注意引号,它们必须是反引号!“`”):

    $ javac -cp `hadoop classpath` WordCount.java
    

    【讨论】:

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