@Override
    public void onUIReset(PtrFrameLayout frame) {
        PtrUIHandlerHolder current = this;
        do {
            final PtrUIHandler handler = current.getHandler();
            if (null != handler) {
                handler.onUIReset(frame);
            }
        } while ((current = current.mNext) != null);
    }
A single linked list to wrap PtrUIHandler
ptr-lib/src/in/srain/cube/views/ptr/PtrUIHandlerHolder.java