Hi Mikhail, Thanks a lot for your clear response.
--Prateek. On Sat, Feb 6, 2010 at 4:06 PM, Mikhail Yakshin <greycat.na....@gmail.com>wrote: > Hi, > > > 1) I have 3 files, namely MaxTemperature.java, MaxTemperatureMapper.java, > > MaxTemperatureReducer.java. Now, I have to compile them to get the > '.class' > > files which would be used by 'hadoop' command. I tried the following: > > > > 'javac -cp .:/hadoop/lib MaxTemperatureMapper.java' > > > > But it gives me the error that it doesn't recognize the packages ' > > org.apache.hadoop.io', 'org.apache.hadoop.mapred' and so on. > > > > Can someone suggest something about that? > > Well, for a start, adding "/hadoop/lib" to your classpath is: > > 1) Literally, yeah, "/hadoop/lib", which means that if will try to > find /hadoop in the root of your filesystem, then it will try to find > "lib" in it. If you meant "hadoop" subdirectory in your current > directory, use "hadoop/lib", not "/hadoop/lib". > > 2) You have to add individual jars in classpath, i.e. > "hadoop/lib/hadoop-0.18.3-core.jar:hadoop/lib/hadoop-0.18.3-test.jar:...", > etc. In recent versions of JDK, you can also specify "hadoop/lib/*", > but make sure you add quotes on this or escape "*" somehow, so it > won't get expanded with your shell. > > > 2) Also, do we have to make the '.class' files by ourselves necessarily. > Or > > is it somehow possible that hadoop will make .class files by itself (from > > the .java source files)? > > Nope, Hadoop is not a Java compiler. Moreover, it's generally > insufficient to just create .class files - Hadoop generally operates > with .class files packed in .jar archives, which is a standard way of > software distribution for Java. > > Running compilers, packers, etc, by hand is barely a good idea. > Consider using "ant" for building or using an IDE, such as Eclipse, > NetBeans or IDEA. > > -- > WBR, Mikhail Yakshin >
