Part Two of the series on building a mobile chat app for Android with PubNub delves into implementing core chat functionalities using the PubNub API. This segment focuses on setting up message publishing, maintaining an ordered list of received messages, and utilizing a JSON-based structured message format for data extensibility. It outlines the process of initializing PubNub, creating and managing channels, and implementing a chat tab with dynamic message updates in the user interface. The use of adapters to bridge dynamic data with the Android UI is explained, ensuring real-time data display from PubNub channels. The article also touches on managing various app lifecycle events and network connectivity challenges, hinting at future content addressing these topics. Additionally, instructions for running the application in Android Studio are provided, showcasing the app's ability to exchange messages across multiple devices, with plans for expanding features like real-time user presence in subsequent parts of the series.