One of the most prominent changes in the Lollipop release is a redesigned user interface built around a responsive
design language referred to as "
material design". Other changes include improvements to the notification system which allow notifications to be accessed from the lockscreen, and to be displayed within other apps as banners across the top of the screen. Internal changes were also made to the platform, with the
Android Runtime (ART) officially replacing
Dalvik for improved application performance, and changes intended to improve and optimize battery usage, known internally as Project Volta.
Development
Android 5.0 was first unveiled under the codename "Android L" on June 25, 2014 during a keynote presentation at the
Google I/O developers' conference. Alongside Lollipop, the presentation focused on a number of new Android-oriented platforms and technologies, including
Android TV, in-car platform
Android Auto,
wearable computing platform
Android Wear, and health tracking platform
Google Fit.
Part of the presentation was dedicated to a new cross-platform
design language referred to as "material design". Expanding upon the "
card" motifs first seen in
Google Now, it is a cleaner design with increased use of grid-based layouts, responsive animations and transitions, padding, and depth effects such as lighting and shadows. Designer
Matías Duarte explained that "unlike real paper, our digital material can expand and reform intelligently. Material has physical surfaces and edges. Seams and shadows provide meaning about what you can touch." The material design language will not only be used on Android, but across Google's suite of web software as well, providing a consistent experience across all platforms.
Feature
Android 5.0 introduces a refreshed notification system. Individual notifications are now displayed on cards to adhere to the material design language, and batches of notifications can be grouped by the app that produced them. Notifications are now displayed on the
lock screen as cards, and "heads up" notifications can also be displayed as large banners across the top of the screen, along with their respective action buttons.A do-not-disturb feature is also added for notifications. The recent apps menu was redesigned to use a three-dimensional stack of cards to represent open apps. Individual apps can also display multiple cards in the recent menu, rather than only one entry per app; for example, a web browser can show all of its open
tabs as individual cards.
Lollipop also contains major new platform features for developers, with over 5,000 new
APIs added for use by applications. Additionally, the
Dalvik virtual machine was officially replaced by
Android Runtime (ART), which is a new
runtime environment that was introduced as a
technology preview in KitKat.ART is a cross-platform runtime which supports the
x86,
ARM, and
MIPS architectures in both
32-bit and
64-bit environments. Unlike Dalvik, which uses
just-in-time compilation (JIT), ART compiles apps
upon installation, which are then run exclusively from the compiled version from then on. This technique removes the processing overhead associated with the JIT process, improving system performance.
Lollipop also aims to improve battery consumption through a series of optimizations known as "Project Volta". Among its changes are a new battery saver mode, job scheduling APIs which can restrict certain tasks to only occur over
Wi-Fi, and batching of tasks to reduce the overall amount of time that internal radios are active. The new developer tool called "Battery Historian" can be used for tracking battery consumption by apps while in use.The Android Extension Pack APIs also provide graphics functions such as new
shaders, aiming to provide
PC-level graphics for 3D games on Android devices.
A number of system-level,
enterprise-oriented features were also introduced under the banner "Android for Work":
Samsung contributed its
Knox security framework for segregating personal and work-oriented data from each other on a device, along with accompanying APIs for managing the environment. Devices can also be configured so that users do not have to unlock their device with a PIN or pattern if it is within a trusted, physical location, or is in proximity to a user's Android Wear device. Device encryption will be enabled by default.
Release
A second developer preview build, LPV81C, was released on August 7, 2014, alongside the beta version of the
Google Fit platform and SDK. As with the previous build, the second developer preview build is available only for the Nexus 5 and 2013 Nexus 7.
On October 15, 2014, Google officially announced that Android L would be known as Android 5.0 "Lollipop". The company also unveiled launch devices for Android 5.0—including Motorola's
Nexus 6 and
HTC's
Nexus 9—for release on November 3, 2014.Google stated that Nexus (including the
Nexus 4, 5, 7, and
10) and
Google Play edition devices would receive updates to Lollipop "in the coming weeks"; one more developer preview build for Nexus devices and the new SDK revision for application developers would be released on October 17, 2014. Update schedules for third-party Android devices may vary by manufacturer.
On the 3rd of November 2014, Google began pushing the source code for Android Lollipop onto the Git at Google Source page, signifying that Lollipop 5.0 had been released for general availability. Manufacturers can now start working on the 5.0 update for their respective flagships, while Google's own Nexus line of smartphones and tablets will begin to receive the OTA update in a couple of weeks. The factory images are expected to be uploaded in a few days time.
