problems building the protobuf example apps

Question

I'm new to protobufs and was trying to learn more about using them. I've downloaded the protobuf packaged from here. There is a README.txt file inside the examples folder of the archive which gives instructions on how to build 2 example applications. However when I follow those instructions for building the java application:

make java

I get a lot of errors followed by:

100 errors
make: * [javac_middleman] Error 1

All of the 100 errors seem to be classpath related, as this is a typical example:

com/example/tutorial/AddressBookProtos.java:37: error: package com.google.protobuf does not exist

Any ideas about how to get passed this?

Answer 1

The problem is that for some reason protobuf jar is not added to the classpath during compilation. To fix it you should open examples/Makefile and add -cp protobuf-java-2.4.1.jar at the end of java complilation line javac AddPerson.java ListPeople.java com/example/tutorial/AddressBookProtos.java.

P.S. If you built you protobufs with maven the jar is located at ~/.m2/repository/com/google/protobuf/protobuf-java/2.4.1/protobuf-java-2.4.1.jar (version of the jar might be different)