What you get in Android P(Android 9.0) Unique from other android version

Android P Or Android 9.0

Tech Gyan 18

To boost app compatibility with Android P, Google will gradually limit access over time to non-SDK-provided device interfaces.

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The Android P beta's updated SDK provides system images for testing on the Android Emulator and on various Pixel devices.

Other improvements in Android P include:

For security, a more consistent UI for fingerprint authentication.
More-accurate indoor positioning via Round-Trip-Time (RTT) APIs, with which apps can measure the distance to Wi-Fi access points. With knowledge of the distance to access points, device position can be calculated as granularly as one meter.
Enhanced performance and efficiency on all apps in the ART (Android Runtime).
New APIs in the Autofill Framework, to save time in filling out forms in password managers.
To assist with mobile payments, an implementation of GlobalPlatform Open Mobile API.
Display cutout support, to support full-screen content on new device screen sizes.
New APIs have been added to manage display of content onscreen, such as to support notches.
The MessagingStyle feature for message notifications that highlights who is messaging and ways to reply.
A multicamera API, for access to streams simultaneously from two or more cameras. Developers can build features for devices that have dual-front or dual-back cameras such as seamless zoom and stereo vision. Also, developers can use this API to call a logical or fused camera stream and automatically switch among cameras.
Sessions parameters for cameras, to reduce delays after initial capture.
A surface-sharing capability, so camera clients can handle different use cases with no need to stop and start streaming.
APIs for display-based flash support as well as app-level image stabilization and special effects.