Google has released an early preview of the Android 3.0 software development kit (SDK). Android 3.0—codenamed Honeycomb—introduces Android's new tablet user interface, which is expected to officially debut next month on Motorola's Xoom tablet. Developers will be able to use the SDK preview to get a head start on updating their applications to support the tablet form factor.

The SDK also offers Android enthusiasts an early look at the new tablet user interface. It includes a partial Android 3.0 environment that runs in the Android emulator. Due to the emulator's glacially slow performance, however, we weren't really able to get an accurate feel for the responsiveness of the interface. The following screenshots highlight some of the major characteristics that differentiate Honeycomb's tablet interface from Android's conventional smartphone interface, but keep in mind that it's still just a preview build for developers and might not accurately represent what the platform will look like on an actual product.

The Honeycomb home screen comes with sophisticated scrolling widgets and can accommodate much more content than the conventional Android home screen. Like the traditional Android home screen, it still comes with multiple pages that the user can rotate through by swiping right and left.

You can add elements by clicking the plus button in the top corner, which will launch the home screen editor. It will let you drag widgets and application shortcuts to any of the five home screen pages.





The Android application drawer also got a significant overhaul. It is accessible through an "Apps" button that appears in the top corner of the screen. The application drawer has tabs at the top that act like filters.

The platform's settings panel has gained a dual-column user interface that displays the preference categories as a sidebar. It also takes advantage of the greater screen space by spreading out the elements and giving more room to section headings.

The e-mail client has gained multicolumn layout. In the main view, the user sees their e-mail folders alongside the list of messages in the selected folder. When a user selects a message, the interface adjusts to show a list of messages on the left-hand side and the message content in a column on the right-hand side. You can see a menu button in the top right-hand corner.





The Android Web browser has gained a tabbed user interface that more closely resembles a desktop browser. The browser crashed almost instantly whenever we tried to interact with it in the emulator, so we didn't really get an opportunity to try out multiple tabs or look at the bookmark system.

The SDK doesn't come with any of the Google-branded applications like the GMail client or the Android Market, so we were unable to test those. Some of the applications, such as the music player, don't appear to have been fully updated for the new user interface yet. Other applications, such as the calculator, have had some minor layout adjustments so that they look right at larger screen sizes.





Honeycomb's notification system is somewhat different than in conventional Android phone environments. Notifications pop up as toaster-style bubbles in the bottom right-hand corner of the screen. You can tap the area next to the click to see them. There is also a system status panel that can be accessed through the notification area. It has an orientation lock feature and allows the user to adjust screen brightness and connectivity settings.

Multitasking in Honeycomb appears to function in much the same way it does on Android phones, but with an expanded user interface. You can switch between tasks by hitting the overlapping window icon in the bottom-left area—it's roughly analogous to doing a long-press on the physical home button on a regular Android phone. It will pop up a list of the recently-used applications and allow you to switch to one by tapping its icon. On actual hardware, this multitasking view will reportedly show actual application thumbnails instead of just the program icon.

Although Google has already confirmed that Android 3.0 will eventually ship on smartphones, there are a lot of unanswered questions about when and how this tablet-centric user interface will be adapted for handsets. In an effort to gain some insight into Honeycomb's ability to scale down, we reconfigured the emulator to run the Honeycomb system image at a standard WVGA resolution.

It successfully booted and presented a standard Android phone user interface with a conventional notification bar at the top, but the home screen process crashed before it rendered. It's worth noting that the message about the crash was properly scaled down to fit the phone screen size. We wanted to try out some of the applications in Honeycomb at that resolution, but the lack of a launcher made it a bit difficult. To work around the limitation, we made a very simple Android application that uses the platform's IPC system to launch the Web browser.

In the screenshot above on the right, you can see what Honeycomb's browser and notification bar look like at a regular phone resolution. It appears as though the platform automatically uses the standard Android interface elements (albeit with slightly broken artwork) when it is displayed at a conventional phone resolution. This suggests that we might not have to wait long before Android 3.0 arrives on phones in addition to tablets.

The Honeycomb tablet interface has some novel elements, but it feels very incomplete and has a lot of rough edges. It's important to remember that this is still an early preview build, however. We are hoping to see a more polished and mature version next month when it arrives on actual hardware. For more details about Honeycomb, you can refer to the SDK release notes. Developers can download the SDK from the Android developer site.