My rule of thumb:
- if you see "java.awt" or "javax.swing" in any package import, run away.
- if you need to download a native library to run a hello world, run away too.
The rest is/should be fair game. Try to run a hello world on the device.
What kind of graphics?
- for charts on android, http://code.google.com/p/afreechart/
- for maths calculations, http://commons.apache.org/math/
- for opengl graphics on android, it's already a pain with all the fragmentation here. There's OpenglES10 (but no longer implemented on Xoom), OpenglES20 (2.2/2.3 and up, but no VBO support on 2.2), Renderscript (3.0 and up), JNI (if you want to program in C), MonoAndroid (for mono, you need to pay for that though)...
- otherwise, just go with the official Canvas API http://developer.android.com/guide/topics/graphics/index.htm...
The rest is/should be fair game. Try to run a hello world on the device.