I have written C programs, and also called C programs from within Java using JNI. But this experience is very slight, and except for saying that I can and have done it, and might could do so in a pinch with enough time, I could not call myself a C programmer.

On the other hand, C programming syntax is not so terribly differnent than Java, and I would feel comfortable taking most any program written in C and converting it to Java, perhaps excluding external library calls.