Just go through in net, there are some pdf readers in android namely..
Android PDF Viewer
VuDroid
droidreader
android-pdf
APDFViewer
I think most of these are use JNI(In native load C,C++ library) to render pdf file. So You have to some basic knowledge of how JNI works.
Or If you want to make your own PDF reader then you can use any third party C,C++ library for render PDF file and build a shared library and make a call from your android app (Using JNI) but is to hard work(I know I gone through this process).. :-) All the best..!