Updated 2026-10-13: This article records the historical approach of observing notifications through accessibility events before Android 4.3. That approach is outdated for a general notification center. Android 4.3 (API 18) introduced NotificationListenerService; section 4 adds a minimal listener for Android 7.0 (API 24) and later. The legacy examples explain the earlier implementation and do not provide a complete notification list.

1. Accessibility Service in Practice

The previous article introduced accessibility services and their basic configuration. This article follows the original implementation of a simple notification center. Android’s system notification UI displays notifications from apps and system components, such as missed calls, screenshots, weather, and news updates. Before Android 4.3, ordinary third-party apps did not have a public API to query the active notification list. Accessibility events offered a limited way to observe notifications; Android 4.3 added the dedicated NotificationListenerService.getActiveNotifications() API.