question java compile problem for HadoopDFSFileReadWrite.java in Support Questions

java compile problem for HadoopDFSFileReadWrite.java

ilh_cho — Sun, 12 Feb 2017 10:12:55 GMT

I set up HDP 2.4 Sandbox on Virtualbox on my windows machine.

The pi program works. So, I guess the installation was OK.

Then, I tried to compile a java program from wiki (http://wiki.apache.org/hadoop/HadoopDFSReadWrite.java), but it did not work.

The following shows the compile command and error messages. Basically it does not recognize the org.apache.hadoop.conf package.

javac -cp 'hadoop classpath' HadoopDFSFileReadWrite.java HadoopDFSFileReadWrite.java:22: error: package org.apache.hadoop.conf does not exist import org.apache.hadoop.conf.Configuration; ^ HadoopDFSFileReadWrite.java:23: error: package org.apache.hadoop.fs does not exist import org.apache.hadoop.fs.FileSystem; ^

...

Is this package recognized by HortowonWorks sandbox distribution?

Many thanks.

Re: java compile problem for HadoopDFSFileReadWrite.java

jsensharma — Sun, 12 Feb 2017 11:09:22 GMT

@ilhyung cho

in your command you are not using the correct Quotation marks.

Incorrect:

javac -cp 'hadoop classpath' HadoopDFSFileReadWrite.java

Correct:

javac -cp `hadoop classpath` HadoopDFSFileReadWrite.java

Everything you type between backticks is evaluated (executed) by the shell before the main command, Whereas the same is not the case with single quotation marks.

For Example:

[root@sandbox ~]# echo 'hadoop classpath'
hadoop classpath


[root@sandbox ~]# echo `hadoop classpath`
/usr/hdp/2.5.0.0-1245/hadoop/conf:/usr/hdp/2.5.0.0-1245/hadoop/lib/*:/usr/hdp/2.5.0.0-1245/hadoop/.//*:/usr/hdp/2.5.0.0-1245/hadoop-hdfs/./:/usr/hdp/2.5.0.0-1245/hadoop-hdfs/lib/*:/usr/hdp/2.5.0.0-1245/hadoop-hdfs/.//*:/usr/hdp/2.5.0.0-1245/hadoop-yarn/lib/*:/usr/hdp/2.5.0.0-1245/hadoop-yarn/.//*:/usr/hdp/2.5.0.0-1245/hadoop-mapreduce/lib/*:/usr/hdp/2.5.0.0-1245/hadoop-mapreduce/.//*::jdbc-mysql.jar:mysql-connector-java-5.1.17.jar:mysql-connector-java-5.1.37.jar:mysql-connector-java.jar:/usr/hdp/2.5.0.0-1245/tez/*:/usr/hdp/2.5.0.0-1245/tez/lib/*:/usr/hdp/2.5.0.0-1245/tez/conf

Re: java compile problem for HadoopDFSFileReadWrite.java

ilh_cho — Sun, 12 Feb 2017 11:51:22 GMT

Thanks for quick reply. The book I follow does not show them as backticks. Now I remember those Unix shell stuff. 😉

It works.

Re: java compile problem for HadoopDFSFileReadWrite.java

jsensharma — Sun, 12 Feb 2017 12:14:21 GMT

@ilhyung cho

Good to know that it works now. It will be great if you mark this thread/answer as accepted (by clicking the accept link)