android-Designing Effective Navigation,Planning Screens and Their Relationships

 >Designing Effective Navigation

 One of the very first steps to designing and developing an Android application is to determine what users are able to see and do with the app.Once you know what kinds of data users are interacting with in the app, the next step is to design the interactions that allow users to navigate across, into, and back out from the different pieces of content within the app.

 You should also have basic familiarity with the Action Bar (pattern docs at Android Design), used across most applications in devices running Android 3.0 and later.

>Planning Screens and Their Relationships

 Most apps have an inherent information model that can be expressed as a tree or graph of object types. Software engineers and data architects often use entity-relationship diagrams (ERDs) to describe an application's information model.

 >In our example application, we want to enable users to view, save, and share categorized stories and photos. Below is an exhaustive list of screens that covers these use cases.

• Home or "launchpad" screen for accessing stories and photos
• List of categories
• List of news stories for a given category
• Story detail view (from which we can save and share)
• List of photos, uncategorized
• Photo detail view (from which we can save and share)
• List of all saved items
• List of saved photos
• List of saved stories

 >A simplistic user interface could consist of lists and buttons leading to child screens:

• Buttons leading to different sections (e.g., stories, photos, saved items)
• Vertical lists representing collections (e.g., story lists, photo lists, etc.)
• Detail information (e.g., story view, full-screen photo view, etc.)