Function with_activity

pub fn with_activity<F, R>(f: F) -> Result<R>
where
    F: for<'a, 'b, 'c, 'd> FnOnce(&'a mut JNIEnv<'b>, &'c JObject<'d>) -> R,

Invokes the given closure f with the current JNI environment and the current activity.

Returns None upon error, including:

• If the function that gets the current activity and JNI environment has not been set.
• If the current JNI environment cannot be obtained.