I set up an Android app with OpenCV yesterday.
There are two ways to go about it
- Use OpenCV for Android
- Use JavaCV
OpenCV for Android is more fully supported than JavaCV. Follow Google's instructions to install Eclipse, the Android SDK and NDK (don't forget the NDK! It is needed to run C++ code. Your apps will mysteriously crash without it). Afterwards, follow this tutorial to install openCV. Try out the sample applications.
Alternatively, you can try using JavaCV instead of OpenCV for Android. This means you won't need to setup the Android NDK. It also means you won't need to write any C++. I didn't try this. But I suspect it is easier. The downside is: it doesn't support everything OpenCV does.