Google released the first developer preview of “Android O” on 21 March 2017, five months before the final release. Dave Burke’s post called it early: “there are more features coming, and there’s still plenty of stabilization and performance work ahead of us. But it’s booting :)”.
| Release date | 21 March 2017 |
| Build | OPP1.170223.013, per the AOSP tag “Android O Preview Release 1” |
| Devices | Nexus 5X, Nexus 6P, Nexus Player, Pixel, Pixel XL and Pixel C; Android Emulator; Wear emulator |
| How to get it | Manual download and flash only; Android Beta was not open for O |
| Platform stability | No; APIs still changing |
Most of what defines Android 8.0 was already in this build: the background
limits on implicit broadcasts, services and location updates; notification
channels; the autofill framework; picture-in-picture on phones and tablets;
fonts as an XML resource; adaptive icons; wide-gamut colour per activity;
Wi-Fi Aware and the LDAC codec; the AAudio native audio API, released as an
early version for feedback; multiprocess WebView by default with Safe
Browsing; and java.time. Google asked developers to read the background
limits first, because they “represent a significant change in Android”.
Google’s advice was to test the current app on the preview and publish a
compatible update without changing targetSdkVersion. Support Library
26.0.0 came out as an alpha the same day and raised its minSdkVersion
to 14. Google took preview bug reports in Issue Tracker, the tool it also
uses internally.