gistfile1.cs

[Register ("android/accounts/AccountManagerFuture", DoNotGenerateAcw=true)]
interface IAccountManagerFuture {
    [Register ("cancel", "(Z)Z", "GetCancelHandler:AccountManagerFutureInvoker, YourAssemblyName, Version=0.0.0")]
    bool Cancel (bool mayInterruptIfRunning);

    // ...
}

class IAccountManagerFutureInvoker : IAccountManagerFuture {

    public IAccountManagerFutureInvoker (IntPtr handle, JniHandleOwnership transfer)
        : base (handle, transfer)
    {
        IntPtr local_ref = JNIEnv.GetObjectClass (Handle);
        this.class_ref = JNIEnv.NewGlobalRef (local_ref);
        JNIEnv.DeleteLocalRef (local_ref);
    }

    protected override void Dispose (bool disposing)
    {
        if (this.class_ref != IntPtr.Zero)
            JNIEnv.DeleteGlobalRef (this.class_ref);
        this.class_ref = IntPtr.Zero;
        base.Dispose (disposing);
    }

    protected override IntPtr ThresholdClass {
        get { return class_ref; }
    }

    protected override System.Type ThresholdType {
        get { return typeof (IAccountManagerFutureInvoker); }
    }

    static Delegate cb_cancel;
    static Delegate GetCancelHandler ()
    {
        if (cb_cancel == null)
            cb_cancel = JNINativeWrapper.CreateDelegate ((Action<IntPtr, IntPtr>) n_Cancel);
        return cb_cancel;
    }

    static void n_Cancel (IntPtr jnienv, IntPtr native__this, bool mayInterruptIfRunning)
    {
        IAccountManagerFuture __this = Java.Lang.Object.GetObject<IAccountManagerFuture> (native__this, JniHandleOwnership.DoNotTransfer);
        return __this.Cancel (mayInterruptIfRunning);
    }

    IntPtr id_cancel;
    public bool Cancel (bool mayInterruptIfRunning)
    {
        if (id_cancel == IntPtr.Zero)
            id_cancel = JNIEnv.GetMethodID (class_ref, "cancel", "(Z)Z");
        return JNIEnv.CallBooleanMethod (Handle, id_run, new JValue (mayInterruptIfRunning));
    }    
}