Android NDK limitations?

Question

I have a question about the limitations of what you can do in native code on the Android platform.

Basically I have developed a library in native C code that uses UDP so

Answer 1

The Native Android API is a nice article for NDK.

is it possible to just use the Java for the GUI and then all processing in native code?

Yes. And you need to set appropriate permissions to your AndroidManifest.

record audio, play it,

You need to use OpenSL ES API for recording and playing audio in the native side. It means your application should be for Android 2.3 or later.

Or, NVIDIA provides a framework that allow we to be able to develop using C++ for Android events, sensors, audio and so on even though for Android 2.2 or earlier.

Tegra Resources - Android SDK & NDK sample applications and documentation