The document outlines a step-by-step approach to developing applications for various devices with minimal redundancy and maximum efficiency, addressing high-level UX design, reusable components, and fragment implementation. It provides tactical considerations for layout and graphics, as well as testing methods and alternative strategies for targeting specific devices. The ultimate aim is to deliver an effective user experience across different screen sizes while maintaining code quality and reducing bugs.

1. Dealing with Different
Devices

2. Objective: Minimal Redundancy
● More code = more cost
– More development time initially
– Greater odds of bugs
– More maintenance over time
● Aim for maximum targets with the least
feasible code

3. Step #1: Identify Targets
● Where Is Your App Really Going to be Used?
– Outside of US? Small screens popular
– Heavily dependent on mobile data? Tablets less
likely, TVs pretty much out
● Business-Focused Restrictions
– Distribution partners (e.g., OEM deals)
– Enterprise requirements

4. Step #2: High-Level UX Design
● What Are the Major Functions?
– E.g., Gmail = labels, conversations, messages,
composition
● How Are the Functions Delivered?
– E.g., Gmail = one per screen on phones,
combined on tablets
● What Functional Differences Are There?
– E.g., something only on tablets

5. Step #3: ID Reusable Portions
● Where Are You Combining Things?
– Tablet screen = combination of multiple phone
screens
– Only min0r differences in functionality, look and
feel

6. Step #4: Apply Fragments
● Fragments in an MVC World
– Models = POJOs, database+helper, whatever
– Views = widgets
– Controller = fragments
– Activities = orchestration

7. Step #4: Apply Fragments
Activity A Activity C
Tablet
1 2 3
Activity A Activity B Activity C
TV 1 2 3

8. Step #4: Apply Fragments
● Orchestration via Listeners
– Define interface for the event listener
– Activity supplies implementation to fragment
– Fragment calls listener methods as needed
– Activity responds
● Dynamic fragment or reconfigure existing
fragment
● Start an activity

9. Step #4: Apply Fragments
● Hoped-For Outcomes
– Fragments directly usable in all screen sizes
● 1 per activity in small/normal screens
● 1+ per activity in large/xlarge screens
● Fragment implementations oblivious to where other
fragments reside
– Views and models unaffected

10. Step #5: Tactical Considerations
● Use density-independent dimensions
● Use stretchable graphics
– ShapeDrawable
– Nine-patch PNGs
– SVG (via add-on library)

11. Step #5: Tactical Considerations
● Tell Android where whitespace goes
– LinearLayout and android:layout_weight
– TableLayout and android:stretchColumns
– RelativeLayout and wise choice of rules
● Get graphics designer to design with rules in mind!

12. Step #5: Tactical Considerations
● Resource Set Strategy
– Drawables by Density
● Want image to stay roughly the same size
– Layout by Screen Size
● Apply appropriate fragments, sized and positioned
as needed
– Values by Density (dimensions)
– New in 3.2: minimum resolution resource sets

13. Step #5: Tactical Considerations
● API Versions and Backwards Compatibility
– Class Detection
– Reflection
– Conditional Class Loading
● Newer API only
● Abstract class and multiple API concrete
implementations
– Why? For other tablet features
● E.g., work with action bar

14. Step #6: Testing
● Emulators
● Devices
– Owned
– Loaned (e.g., user group events, device labs at
conferences)
– DeviceAnywhere and similar services
– Controlled beta test release

15. Alternative #1: Market Filtering
● Upload Multiple APKs
– Each targeting a different device spec
● Apply Market Filters
– APKs only delivered to devices on which it
should work

16. Alternative #2: Manifest Filtering
● <compatible-screens>
● <supports-screens>
● <uses-configuration>
● <uses-feature>
● <uses-sdk>

17. Alternative #3: HTML5
● Detect window size or user agent, use
appropriate formatting
– Screen density can be a challenge
● Use PhoneGap to convert into installable APK
● Bonus: cross-platform
● Cons: limited device integration, “non-native”
feel