The new async API definitely changes things, and will probably make it easier to port to Android.

One problem I see is that doing anything Java-related in Rust requires a JavaVM, which unfortunately can't be obtained from JNI_CreateJavaVM() or JNI_GetCreatedJavaVMs(). It can only be obtained by implementing JNI_OnLoad() in your library or as a parameter to a JNI function. This makes it impossible to implement Java support without either:

Adding parameters to Manager::new() or
Creating a global variable (ick!) which is initialized by JNI_OnLoad() (or some init function which gets called by another library), similar to how blurdroid does it.

Manager::new() is not currently bound by a trait, which makes it tempting to simply add a JavaVM argument to Manager::new(), but this would make things slightly more difficult for Android clients, which now have to conditionally (by #[cfg]) pass a JavaVM around in their Bluetooth code.

Using a global init approach limits the library to a single Java VM (which isn't a problem in Android, since Android only allows one VM per process anyway), requires the client to call the init function if it already implements JNI_OnLoad(), and makes Rust angry by creating global variables.

Neither option is very appealing. What are your thoughts? Any other ideas on how to make this work?

Uh oh!

Add Android Support #8

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