Today Microsoft has released the Office 365 software development kit for Android. With it, the company wants to invite developers to access Office data inside their apps. The SDK provides APIs granting permission to call upon SharePoint lists and files, along with Exchange calendars, contacts, and mail. The preview is available for download straight from GitHub.
The SDK requires Android 4.0.3 or higher to run, and Microsoft has shared an introductory blog post to get you started. If you're interested in developing for the broader Office 365 ecosystem instead, the Office Blog has provided far more details regarding what options are now available.
Source: Microsoft Open Technologies