1. Usability and Performance Rules of Thumb for Mobile Java Developers Jackson Feijó Filho Software Developer Lightning talk at Java Mobile, Media & Embedded Developer Days – Santa Clara, CA January, 2009

2. Of usability and performance for mobile java developers - lightning talk Rules of Thumb Origin of the phrase The earliest citation comes from Sir William Hope’s The Complete Fencing- Master, second edition, 1692, page 157: "What he doth, he doth by rule of thumb, and not by art." The term is thought to originate with wood workers who used the length of their thumbs rather than rulers for measuring things, cementing its modern use as an inaccurate, but reliable and convenient standard.

3. Of usability and performance for mobile java developers - lightning talk Rules of Thumb Use cases: Under the absence of an usability expert on the team. All through the developent process. Solo or pet projects. Warning: no silver bullets. Attention and good sense instead.

4. Of usability and performance for mobile java developers - lightning talk Rules of Thumb Lightning Definitions and Principles: Usability: how easy user interfaces are to use. Usability framework can be composed of: Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design? Efficiency: Once users have learned the design, how quickly can they perform tasks? Memorability: When users return to the design after a period of not using it, how easily can they re establish proficiency? Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors? Satisfaction: How pleasant is it to use the design?

5. Of usability and performance for mobile java developers - lightning talk Rules of Thumb Paper Prototyping Paper prototyping is a widely used method in the user-centered design process. -> Get a printed frame of the target device of your application. -> Paper stickers Applying paper prototypes: Communication in the team Usability testing Design testing Information architecture

6. Of usability and performance for mobile java developers - lightning talk Rules of Thumb That said, let the THUMBS begin!!! Take users into account in every phase of the application development process Success in developing usable products requires that usability be designed into the product right from the start. Know the users and design for them Having key features clearly visible and working properly is better than having too many technical functions. Study your target users Product design must understand who the target users are and what their culture is like right from the start.

7. Of usability and performance for mobile java developers - lightning talk Rules of Thumb Hide rarely used features in Options menu Before doing that – make sure they are rarely used by most users! Make sure user fills needed information Whenever possible, provide default values Users often do not have an idea what the setting item or value in a field should be. Avoid long forms Even if form items are not mandatory, many users put time into filling the fields just because they are there – not because they need to.

8. Of usability and performance for mobile java developers - lightning talk Rules of Thumb Take care with colors, Colors have culture-dependent meanings, as do icons and graphics. The color red, for example, may be used to represent a warning or an error message, but in another culture it may be used to promote a positive experience.

9. Of usability and performance for mobile java developers - lightning talk Rules of Thumb Use consistent terminology and the user's language and terms Make sure users understand the terms used, avoid acronyms, and make sure the text is grammatically correct. Give useful feedback to the user Let the user know if an action was successful or not. If processing takes more than 0.5 seconds, indicate that something is happening.

10. Of usability and performance for mobile java developers - lightning talk Rules of Thumb Provide consistent softkey labels Consistent softkey labels in mobile applications enhance learnability and user experience. Use the left softkey for positive actions such as OK, Select, and Menu, and the right softkey for Cancel, Back, and Quit. When the middle softkey is available, use it for the action that the user will most probably do in a certain situation.

11. Of usability and performance for mobile java developers - lightning talk Rules of Thumb Create your own usability checklist! Experience will tell which items of the usability checklist are most important and which ones are missing. Different target users may require different usability checklist items.

12. Thank you pv1.7