Activities Vs. Fragments

An exploration of when to use Activities and when to use Fragments

Transcript

1. Activities vs. Fragments
   Bryan Herbst – Senior Software Engineer, The Nerdery
   

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2. Activity
   “An activity is a single, focused thing that the user can do.”
   - Android API documentation
   

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3. Fragment
   “A Fragment represents a behavior or a portion of user interface in an Activity.”
   “[…] You can think of a fragment as a modular section of an activity.”
   -Android API documentation
   

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4. IO
   

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5. Activity- What it is
    Entry point to the application
    Set of Fragments with related purpose
    Easy to manage navigation
   

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6. Activity- What it isn’t
    Scary or evil
    Super lightweight
    Reusable
   

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7. Fragment- What it is
    A specific piece of functionality
    Reusable
    Relatively lightweight
   

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8. Fragment- What it isn’t
    The only option for displaying content in an application
    Easy to manage navigation
   

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9. Where to start?
    Create a navigation map of app
    Focus on hierarchy
    Clearly identify sibling screens (e.g. top level
   nav items) and descendant screens
    Determine entry points to the application
   

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10. Choose your weapon
     Is this screen a potential entry point?
     Yes: Activity
     No: Maybe Fragment
     Is this screen a hierarchical child of another screen (or: should it provide up navigation)?
     Yes: Probably Activity
     No: Maybe Fragment
     Will this UI component be used elsewhere?
     Yes: Fragment
    

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11. Case study: Cartwheel
     Deep linking
     All links route through MainActivity
     Should have let the framework do the work
     Scoreboard
     Re-used throughout the app
     Event bus for updating
    

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12. The Navigation Drawer
    Navigation hub vs. replacement for tabs => Activity vs Fragment
    “Use navigation drawers if:
     You don't want to give up the vertical screen real estate for a dedicated tab bar. “
    -- Android documentation- App Structure
    

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13. Multi-fragment layouts
     AKA “tablet layouts”
     Doesn’t play nice with the single activity navigation drawer!
    

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