Samuel Audet, the author of JavaCV and other cool projects you can check out here, has been working on a port of JNA for Android. I haven’t tested it myself yet, but according to the wiki it has reached a functional state. This port would be very useful to simplify the access to native C libraries on the Android platform when coding with the Java SDK.
Currently, access to native libraries from Java code on Android is done with JNI. However, using JNI can be somewhat difficult and requires writing glue C/C++ code. JNA provides a simpler alternative to JNI, since it only requires Java code, although it comes with a performance cost:
The calling overhead for a single native call using JNA interface mapping can be an order of magnitude (~10X) greater time than equivalent custom JNI
(from the JNA wiki). But this disadvantage is not very relevant in cases where the calling time of the native function is small compared with its execution time. Also, JNA provides a direct mapping mapping method that improves performance significantly.
Given the importance of the Java SDK on the Android platform, makes sense to have a version of JNA for it. Initial discussions on the google code site of the Android project indicated that priority to implement this port by the Android engineers was low, apparently because of performance concerns. With this initial release of JNA for Android by Samuel, it would be interesting to see how this evolves and if it makes possible to access libraries such as GStreamer (some relevant links).