Error occurred when running command 'catkin_make_isolated --install'

edit

Based on UWSim, I want to let a AUV contact with another AUV. Thus I want to make one AUV act as publisher and another one act as subscriber. I add talker.cpp and listener.cpp by editing CMakeLists.txt file shown as below:

add_library(uwsim src/osgOceanScene.cpp

......

src/talker.cpp

src/listener.cpp
)

then I run command catkin_make_isolated --install after sourcing devel_isolated/setup.bash.

The error occurred shown as below:

==> make -j8 -l8 in '/home/gupta/catkin_ws_2/build_isolated/uwsim'

[  1%] Built target media_files

[  7%] Built target uwsim_plugins_simdev

Scanning dependencies of target uwsim

Linking CXX shared library /home/gupta/catkin_ws_2/devel_isolated/uwsim/lib/libuwsim.so

CMakeFiles/uwsim.dir/src/listener.cpp.o: In function `main':

listener.cpp:(.text+0x163): multiple definition of `main'

CMakeFiles/uwsim.dir/src/talker.cpp.o:talker.cpp:(.text+0x0): first defined here

collect2: ld returned 1 exit status

make[2]: *** [/home/gupta/catkin_ws_2/devel_isolated/uwsim/lib/libuwsim.so] Error 1

make[1]: *** [CMakeFiles/uwsim.dir/all] Error 2

make: *** [all] Error 2

<== Failed to process package 'uwsim': 

  Command '/home/gupta/catkin_ws_2/install_isolated/env.sh make -j8 -l8' returned non-zero exit status 2

Reproduce this error by running:

==> cd /home/gupta/catkin_ws_2/build_isolated/uwsim && /home/gupta/catkin_ws_2/install_isolated/env.sh make -j8 -l8

Command failed, exiting.