I wrangled with this problem for a good 5 or 6 hours, pulling my hair out until I finally found a solution. I wanted to post this (not sure if there is a specific place to post solutions to unasked questions) as a solution for others who may run into the same difficulty.
I am coding a C++ project in Netbeans 7.1.1 running on Linux Mint Lisa, and kept on getting an “Undefined reference to XXX” error when trying to use a static variable. Coming from a background in C# and thus not very familiar with header files and the like, I searched for hours expecting to find a problem with the way I declared my variable or my class. I couldn’t find anything…
Go to your nbproject folder in the files explorer in Netbeans. Open up the configurations.xml file. Scroll down to the logicalFolder tag with the attribute name=”SourceFiles”. Make sure that all your .h and .cpp files are included as itemPath tags within the logicalFolder tag! Netbeans correctly added some, but not all of my cpp and h files, hence the problem. Not sure why there would be this inconsistency, as all class and header files were added through the same Netbeans wizard. Anyways, with the configurations file changed, the makefiles were then updated and written correctly on the next build and all functioned as expected. Hope this can help somebody!