Head First Android Development. 3rd Edition

Spis treści ebooka

• Table of Contents (the real thing)
• How to use this book: Intro
  • Who is this book for?
    • Who should probably back away from this book?
  • We know what youre thinking
  • We know what your brain is thinking
  • Metacognition: thinking about thinking
  • Heres what WE did
    • Heres what YOU can do to bend your brain into submission
  • Read me
  • The truly awesome technical review team
  • Acknowledgments
  • OReilly Online Learning
• 1. Getting Started: Diving In
  • Welcome to Androidville
    • Activities define what the app does
    • Layouts define what each screen looks like
    • There may be extra files too
  • Activities and layouts form the backbone of your app
  • Heres what were going to do
  • Android Studio: your development environment
    • You need to install Android Studio
  • Install Android Studio
  • Lets build a basic app
  • How to build the app
    • 1. Create a new project
    • 2. Select a project template
    • 3. Configure your project
  • Youve created your first Android project
  • Dissecting your new project
    • The folder structure includes different types of files
  • Introducing the key files in your project
  • Edit code with the Android Studio editors
    • The code editor
    • The design editor
  • The story so far
  • How to run the app on a physical device
    • 1. Enable USB debugging on your device
    • 2. Set up your computer to detect the device
    • 3. Use a USB cable to plug your device into your computer
    • 4. Run the app
  • How to run the app on a virtual device
  • Create an Android Virtual Device (AVD)
    • Open the Android Virtual Device Manager
    • Select the hardware
    • Select a system image
    • Verify the AVD configuration
    • The virtual device gets created
    • Run the app on the AVD
  • Compile, package, deploy, run
  • Test Drive
  • What just happened?
  • Lets refine the app
    • The app has one activity and one layout
    • The activity controls what the app does
    • The layout controls the apps appearance
  • Whats in the layout?
    • The design editor
    • The code editor
  • activity_main.xml has two elements
  • Update the text displayed in the layout
  • What the code does
  • Test Drive
  • Your Android Toolbox
• 2. Building Interactive Apps: Apps That Do Something
  • Lets build a Beer Adviser app
  • Heres what were going to do
  • Create the project
  • Weve created a default activity and layout
  • A closer look at the design editor
  • Add a button using the design editor
    • Changes in the design editor are reflected in the XML
  • activity_main.xml has a new button
    • Buttons and text views are subclasses of the same Android View class
      • android:id
      • android:layout_width, android:layout_height
      • android:text
  • A closer look at the layout code
    • The <LinearLayout> element
    • The <Button> element
    • The <TextView> element
  • Lets update the layout XML
  • The XML changes are reflected in the design editor
  • Test Drive
  • There are warnings in the layout
    • because theres hardcoded text
  • Put text in a String resource file
    • Android Studio helps you extract String resources
  • Extract the String resource
    • A String resource has been added to strings.xml
  • activity_main.xml uses the String resource
    • You also can extract String resources manually
  • Add and use a new String resource
  • Test Drive
  • Add values to the spinner
    • Adding an array resource is similar to adding a String
  • Add the string-array to strings.xml
    • Get the spinner to display the arrays values
  • The full code for activity_main.xml
  • Test Drive
  • We need to make the app interactive
  • What the MainActivity code looks like
  • A button can listen for on-click events
    • using an OnClickListener
  • Get a reference to the button
    • and call its setOnClickListener method
  • Pass a lambda to the setOnClickListener method
  • How to edit a text views text
    • How to get the spinners value
  • Pool Puzzle
  • Pool Puzzle Solution
  • The updated code for MainActivity.kt
  • What happens when you run the code
  • Test Drive
  • Add the getBeers() method
  • Activity Magnets
  • Activity Magnets Solution
  • The full code for MainActivity.kt
  • What happens when you run the code
  • Test Drive
  • Your Android Toolbox
• 3. Layouts: Being a layout
  • It all starts with a layout
  • Android has different types of layout
    • Use the best layout for your screen design
  • Lets build a linear layout
    • Create a new project
  • How to define a linear layout
  • Orientation can be vertical or horizontal
  • Use padding to add space to the layouts edges
  • The layout code so far
  • An edit text lets you enter text
  • Add views to the layout XML
  • Make a view streeeeetch by adding weight
  • How to add weight to one view
  • How to add weight to multiple views
  • The gravity attribute controls the position of a views contents
  • Values you can use with the android:gravity attribute
  • Layout Magnets
  • Layout Magnets Solution
  • The story so far
  • layout-gravity controls the position of a view within a layout
  • More values you can use with the android:layout-gravity attribute
  • Use margins to add space between views
  • The full linear layout code
  • Test Drive
  • BE the Layout
  • BE the Layout Solution
  • Your activity code tells Android which layout it uses
    • The layouts views are inflated into objects
  • Layout inflation: an example
  • A frame layout stacks its views
    • Create a new project
    • How to define a frame layout
  • Add an image to your project
  • A frame layout stacks views in the order they appear in the layout XML
  • Test Drive
  • All layouts are a type of ViewGroup
    • and a ViewGroup is a type of View
  • A scroll view inserts a vertical scrollbar
  • How to add a scroll view
  • Test Drive
  • Your Android Toolbox
• 4. Constraint Layouts: Draw Up a Blueprint
  • Nested layouts revisited
  • Nesting layouts comes at a price
  • Introducing the constraint layout
    • You design constraint layouts VISUALLY
  • Constraint layouts are part of Android Jetpack
  • Heres what were going to do
    • Create a new project
  • Use Gradle to include Jetpack libraries
    • The project build.gradle needs a Google repository line
    • The app build.gradle includes the constraint layouts library
  • Lets add a constraint layout to activity_main.xml
    • Show the layout in the blueprint
  • Add a button to the blueprint
  • Position views using constraints
    • Well add a horizontal constraint to the button
  • Add a vertical constraint too
  • Use opposing constraints to center views
  • You can delete constraints you no longer need
  • Remove constraints with the constraint widget
    • You can use it to add margins too
  • Changes to the blueprint appear in the XML
  • Views can have bias
  • Test Drive
  • You can change a views size
    • Make the view just big enough
    • Match the views constraints
  • BE the Constraint
  • BE the Constraint Solution
  • Most layouts need multiple views
    • Add a second button to the blueprint
  • You can connect views to other views
  • You can align views too
  • Align views using guidelines
  • Guidelines have a fixed position
  • Create a movable barrier
    • Lets build a layout that uses a barrier
  • Add a horizontal barrier
    • Place the barrier beneath the views
  • Constrain a button under the barrier
  • The full code for activity_main.xml
  • Test Drive
  • Use a chain to control a linear group of views
    • Were going to create a horizontal chain
  • The chain will use three buttons
    • Align the views were going to chain
  • Create the horizontal chain
  • There are different styles of chain
    • Spread spaces out views between the blueprints edges
    • Spread inside moves the first and last view to the edges
    • Packed moves the views together
  • Test Drive
  • A flow is like a multi-line chain
  • How to add a flow
  • You can control the flows appearance
    • Use chain to create a multi-line chain
    • Use aligned to line up the views
  • The full code for activity_main.xml
  • Test Drive
  • Your Android Toolbox
• 5. The Activity Lifecycle: Being an Activity
  • How do activities really work?
    • Introducing the Stopwatch app
  • Create a new project
    • Add String resources for the text labels
    • The layout includes a Chronometer view
  • The full code for activity_main.xml
  • The activity code controls the stopwatch
    • The Chronometers key properties and methods
    • The base property
    • The start() method
    • The stop() method
  • The full code for MainActivity.kt
  • What happens when you run the app
  • Test Drive
    • But theres just one problem
  • What happens when the app runs
  • Rotating the screen changes the device configuration
  • An activitys states
  • The activity lifecycle: from create to destroy
  • Your activity inherits the lifecycle methods
  • Save the current state in a Bundle
    • Add values using put methods
    • Retrieve values using get methods
  • Save the state using onSaveInstanceState()
    • Restore the state using onCreate()
  • The updated MainActivity.kt code
  • What happens when you run the app
  • Test Drive
  • Activity Magnets
  • Activity Magnets Solution
  • Theres more to an activitys life than create and destroy
    • Start, stop, and restart
  • The visible lifecycle
  • We need to implement two more lifecycle methods
    • Implement onStop() to pause the stopwatch
  • Restart the stopwatch when the app becomes visible
  • The updated MainActivity.kt code
  • What happens when you run the app
  • Test Drive
  • What if an activity is only partially visible?
  • The foreground lifecycle
  • Pause the stopwatch if the activitys paused
  • The complete MainActivity.kt code
  • What happens when you run the app
  • Test Drive
  • Your handy guide to the activity lifecycle methods
  • BE the Activity
  • BE the Activity Solution
  • Your Android Toolbox
• 6. Fragments and Navigation: Finding Your Way
  • Most apps need more than one screen
  • Each screen is a fragment
    • WelcomeFragment
    • MessageFragment
    • EncryptFragment
  • Navigate between screens using the Navigation component
  • Heres what were going to do
  • Create a new project
    • Add some String resources
  • Add WelcomeFragment to the project
  • What fragment code looks like
    • Fragment code looks similar to activity code
  • The fragments onCreateView() method
    • Inflate the fragments layout, and return it
  • Fragment layout code looks like activity layout code
  • You display a fragment in a FragmentContainerView
  • Update the activity_main.xml code
    • The full code for MainActivity.kt
  • What the code does
  • Test Drive
  • Pool Puzzle
  • Pool Puzzle Solution
  • Create MessageFragment
  • Update MessageFragments layout
  • Update MessageFragment.kt
  • Use the Navigation component to navigate between fragments
  • Use Gradle to add the Navigation component to your project
    • Add a version number to the project build.gradle file
    • Add a dependency to the app build.gradle file
  • Create a navigation graph
  • Add fragments to the navigation graph
  • Connect fragments using an action
    • Every action needs a unique ID
  • Navigation graphs are XML resources
  • Add a navigation host to the layout using a FragmentContainerView
  • Add a NavHostFragment to activity_main.xml
    • We need to navigate between the fragments
  • Add an OnClickListener to the button
    • Fragment OnClickListener code is a little different
  • Get a navigation controller
    • Tell it where to navigate with an action
  • The full code for WelcomeFragment.kt
  • What happens when the app runs
  • Test Drive
  • Your Android Toolbox
• 7. Safe Args: Passing Information
  • The Secret Message app navigates between fragments
  • MessageFragment needs to pass the message to a new fragment
  • Heres what were going to do
  • Create EncryptFragment
    • and update its layout
  • Update EncryptFragment.kt
  • Add EncryptFragment to the navigation graph
  • The updated nav_graph.xml code
  • MessageFragment needs to navigate to EncryptFragment
  • Test Drive
  • Add Safe Args to the build.gradle files
    • Add a classpath to the project build.gradle file
    • Add the plug-in to the app build.gradle file
  • EncryptFragment needs to accept a String argument
  • The updated nav_graph.xml code
  • MessageFragment needs to pass a message to EncryptFragment
    • You can pass arguments to navigation actions
  • Safe Args generates Directions classes
    • Use a Directions class to add arguments to actions
  • Update the MessageFragment.kt code
  • EncryptFragment needs to get the arguments value
    • Use an Args class to retrieve arguments
    • We need to encrypt the message
  • The full code for EncryptFragment.kt
  • What happens when the app runs
  • Test Drive
  • Navigation Magnets
  • Navigation Magnets Solution
  • What if the user wants to go back?
  • We could change the back behavior
  • Welcome to the back stack
    • A back stack scenario
  • Use the navigation graph to pop fragments off the back stack
  • The updated nav_graph.xml code
  • Test Drive
  • BE the Safe Args Plug-in
  • BE the Safe Args Plug-in Solution
  • Your Android Toolbox
• 8. Navigation ui: Going Places
  • Different apps, different structures
  • Android includes navigation UI components
    • An app bar
    • The bottom navigation bar
    • A navigation drawer
  • How the CatChat app will work
  • Heres what were going to do
  • Create a new project
    • A default app bar gets added
    • by applying a theme
  • The CatChat app will use a Material theme
    • The app build.gradle file needs a Material library dependency
  • Apply a theme in AndroidManifest.xml
  • Define styles in style resource files
  • Styles can override theme colors
    • Color resource files define a set of colors
  • Replace the default app bar with a toolbar
    • Remove the default app bar using a theme
  • A toolbar is a type of View
  • Add the toolbar to activity_main.xml
    • Where did the app name go?
  • Set the toolbar as MainActivitys app bar
  • Test Drive
  • Lets use the toolbar to navigate
    • How toolbar navigation will work
  • Create InboxFragment
  • Create HelpFragment
  • Well use the Navigation component to navigate to HelpFragment
    • Add a version number to the project build.gradle file
    • Add dependencies to the app build.gradle file
  • Add the fragments to a navigation graph
  • Add a navigation host to activity_main.xml
  • Specify items in the toolbar with a menu resource file
  • Lets add a Help item to the menu
  • onCreateOptionsMenu() adds menu items to the toolbar
  • Respond to menu item clicks with onOptionsItemSelected()
  • We need to configure the toolbar
  • Configure the toolbar using an AppBarConfiguration
  • The full code for MainActivity.kt
  • What happens when the app runs
  • Test Drive
  • BE the Menu
  • BE the Menu Solution
  • Most types of UI navigation work with the Navigation component
    • How the bottom navigation bar will work
  • Create SentItemsFragment
  • Add SentItemsFragment to the Navigation graph
  • The bottom navigation bar needs a new menu resource file
  • A bottom navigation bar is a type of View
  • The full code for activity_main.xml
  • Link the bottom navigation bar to the navigation controller
  • The updated code for MainActivity.kt
  • Test Drive
  • A navigation drawer lets you display many navigation items
  • Lets replace the bottom navigation bar with a navigation drawer
  • Navigation drawers deconstructed
  • The drawer gets its items from a menu
  • Add the support section
    • as a separate submenu
  • Highlight the selected item with groups
  • The full code for menu_main.xml
  • Create the navigation drawers header
    • Add the image file
    • and update the nav_header.xml code
  • How to create a navigation drawer
  • The full code for activity_main.xml
    • Weve added a navigation drawer to the layout
  • Configure the toolbars drawer icon
    • and link the drawer to the navigation controller
  • The full code for MainActivity.kt
  • Test Drive
  • Layout Magnets
  • Layout Magnets Solution
  • Your Android Toolbox
• 9. Material Views: A Material World
  • Material is used throughout Androidville
  • The Bits and Pizzas app
  • Heres what well do
  • Create the Bits and Pizzas project
    • Add a Material library dependency to the app build.gradle file
  • Create OrderFragment
  • Display OrderFragment in MainActivitys layout
  • Replace the default app bar with a toolbar
  • Fragments dont have a setSupportActionBar() method
  • Weve added the toolbarnow what?
    • We want the toolbar to respond to scrolls
  • The coordinator layout coordinates animations between views
  • The app bar layout enables toolbar animation
  • Tell the toolbar how to respond to scroll events
  • A nested scroll view makes layout content scrollable
  • The full code for fragment_order.xml
  • Test Drive
  • BE the Layout
  • BE the Layout Solution
  • Lets create a collapsing toolbar
  • How to create a plain collapsing toolbar
  • How to add an image to a collapsing toolbar
  • Add a restaurant image drawable
    • The full code for fragment_order.xml
  • Test Drive
  • Layout Magnets
  • We need to build OrderFragments main content
  • Choose a pizza type using a radio button
  • Radio buttons are a type of compound button
  • A chip is a type of flexible compound button
  • Add multiple chips to a chip group
    • Use isChecked to find out if a chip is checked
  • A FAB is a floating action button
  • You can anchor a FAB to a collapsing toolbar
  • We need to build OrderFragments layout
  • The full code for fragment_order.xml
  • Test Drive
  • Lets make the FAB respond to clicks
  • Add an OnClickListener to the FAB
    • Find out if a pizza type has been selected
  • A toast is a simple pop-up message
    • Add a toast to the FAB OnClickListener
  • Display the pizza order in a snackbar
    • Snackbars can have actions
  • The snackbar code for the pizza order
  • The full code for OrderFragment.kt
  • Test Drive
  • Pool Puzzle
  • Pool Puzzle Solution
  • Layout Magnets Solution
  • Your Android Toolbox
• 10. View Binding: Bound Together
  • Behind the scenes of findViewById()
    • findViewById() looks for a view in the view hierarchy
  • Theres a downside to findViewById()
  • View binding to the rescue
    • View binding is safer and more efficient than findViewById()
  • Heres how well use view binding
  • The Stopwatch app revisited
  • Enable view binding in the app build.gradle file
    • Enabling view binding generates code for each layout
  • How to add view binding to an activity
  • Use the binding property to interact with views
    • The layout code
    • The activity code
  • The full code for MainActivity.kt
  • What the code does
  • Test Drive
  • Activity Magnets
  • Fragments can use view binding too (but the codes a little different)
    • Lets implement view binding in the Bits and Pizzas app
  • Enable view binding for Bits and Pizzas
    • Binding classes are generated for every layout
  • Fragment view binding code is a little different
    • Activities can access views from onCreate()
  • Fragments can access views from onCreateView() to onDestroyView()
  • What fragment view binding code looks like
  • _binding refers to the binding object
    • ...and the binding property provides non-null access to it
  • The full code for OrderFragment.kt
  • Test Drive
  • Activity Magnets Solution
  • Your Android Toolbox
• 11. View Models: Model Behavior
  • Configuration changes revisited
    • There are other problems, too
  • Introducing the view model
    • Why use a view model?
  • What the guessing game will do
  • How the app will be structured
  • Heres what were going to do
    • Create the Guessing Game project
  • Update the project build.gradle file
    • and update the app build.gradle file too
  • The Guessing Game app has two fragments
    • Create GameFragment
    • and then create ResultFragment
  • How navigation should work
    • Create the navigation graph
  • Update the navigation graph
  • Display the current fragment in MainActivitys layout
  • Update GameFragments layout
    • What GameFragment needs to do
  • The GameFragment.kt code
  • Update ResultFragments layout
    • We also need to update ResultFragment.kt
  • The ResultFragment.kt code
  • What happens when the app runs
  • Test Drive
  • The game loses state when the screen rotates
  • A view model holds business logic
  • Add a view model dependency to the app build.gradle file
    • and create a view model
  • The full code for GameViewModel.kt
  • Create a GameViewModel object
    • Use a ViewModelProvider to create view models
  • The updated code for GameFragment.kt
  • What happens when the app runs
  • Test Drive
  • BE the View Model
  • Weve added a view model for GameFragment
    • ResultFragment needs a view model too
  • ResultViewModel needs to hold the result
    • We need to link ResultViewModel to ResultFragment
  • A view model factory creates view models
  • Create the ResultViewModelFactory class
  • Use the factory to create the view model
  • The updated code for ResultFragment.kt
  • What happens when the app runs
  • Test Drive
  • View Model Magnets
  • View Model Magnets Solution
  • BE the View Model Solution
  • Your Android Toolbox
• 12. Live Data: Leaping into Action
  • The Guessing Game app revisited
  • The fragments decide when to update views
    • Let the view model say when a values changed
  • Heres what were going to do
    • Add a live data dependency to the app build.gradle file
  • GameViewModel and GameFragment need to use live data
    • Which view model properties should use live data?
  • Live data objects use a value property
    • The value property can be null
  • The full code for GameViewModel.kt
  • The fragment observes the view model properties and reacts to changes.
  • The full code for GameFragment.kt
  • What happens when the app runs
  • Test Drive
  • Fragments can update GameViewModels properties
    • Keep your privates private
  • The full code for GameViewModel.kt
  • What happens when the app runs
  • Test Drive
  • GameFragment still includes game logic
    • Make GameViewModel decide when the game is over
  • Pool Puzzle
  • Pool Puzzle Solution
  • The full code for GameViewModel.kt
  • Make GameFragment observe the new property
  • What happens when the app runs
  • Fragment Magnets
  • Fragment Magnets Solution
  • Test Drive
  • Your Android Toolbox
• 13. Data Binding: Building Smart Layouts
  • Back to the Guessing Game app
  • The fragments update the views in their layouts
    • We can make the views update themselves instead
  • Heres what were going to do
  • Enable data binding in the app build.gradle file
  • ResultFragment updates the text in its layout
    • How well implement data binding
  • 1. Add <layout> and <data> elements
  • 2. Set the layouts data binding variable
  • 3. Use the layouts data binding variable to access the view model
  • The full code for fragment_result.xml
  • The full code for ResultFragment.kt
  • What happens when the app runs
  • Test Drive
  • Layout Magnets
  • Layout Magnets Solution
  • GameFragment can use data binding too
  • Add <layout> and <data> elements to fragment_game.xml
  • Use the data binding variable to set the layouts text
    • Two of the views need to show extra text
  • String resources revisited
    • String resources can have arguments
    • Add two new String resources to strings.xml
  • The layout can pass parameters to String resources
  • The full code for fragment_game.xml
  • We need to set the gameViewModel variable
    • We also need to make the data binding use live data
  • The full code for GameFragment.kt
  • What happens when the app runs
  • Test Drive
  • You can use data binding to call methods
  • Add finishGame() to GameViewModel.kt
  • Use data binding to make a button call a method when clicked
  • The full code for fragment_game.xml
  • What happens when the app runs
  • Test Drive
  • Pool Puzzle
  • Fireside Chats
  • We can switch off view binding
    • Switch off view binding in the apps build.gradle file
  • Test Drive
  • Binding-Cross
  • Binding-Cross Solution
  • Pool Puzzle Solution
  • Your Android Toolbox
• 14. Room Databases: Room with a View
  • Most apps need to store data
    • Apps can persist data using a database
  • How the app will be structured
  • Room is a database library that sits on top of SQLite
    • Room apps are usually structured using MVVM
  • Heres what were going to do
    • Create the Tasks project
  • Add a variable to the project build.gradle file
    • and update the app build.gradle file, too
  • Create TasksFragment
    • Update TasksFragment.kt
  • Update fragment_tasks.xml
  • Display TasksFragment in MainActivitys layout
    • and check the MainActivity.kt code
  • How Room databases are created
    • 1. A database class
    • 2. Data classes for the tables
    • 3. Interfaces for data access
  • Well store tasks data in a table
    • You define tables with an annotated data class
    • Create the Task data class
  • Specify a table name with @Entity
    • Specify the primary key with @PrimaryKey
    • Specify column names with @ColumnInfo
  • The full code for Task.kt
  • Use an interface to specify data operations
    • Create the TaskDao interface
    • Use @Dao to mark the interface for data access
  • Use @Insert to insert a record
    • Use @Update to update a record
  • Use @Delete to delete a record
    • Use @Query for everything else
  • The full code for TaskDao.kt
  • Create a TaskDatabase abstract class
    • Annotate the class with @Database
  • Add properties for any DAO interfaces
    • Create and return an instance of the database
  • The full code for TaskDatabase.kt
  • MVVM revisited
    • Weve completed all the Model code
    • so lets move on to the ViewModel
  • Create TasksViewModel
  • Database operations can run in slooooow-moooo
    • Well use coroutines to run data access code in the background
  • 1. Mark TaskDaos methods with suspend
  • 2. Launch the insert() method in the background
  • TasksViewModel needs a view model factory
    • Create TasksViewModelFactory
  • TasksViewModelFactory needs a TaskDao
    • The TaskDatabase code has a TaskDao property
  • The updated code for TasksFragment.kt
  • TasksFragment can use data binding
  • Well use data binding to insert a record
    • Set TasksViewModels newTaskName property
    • Call TasksViewModels addTask() method
  • The full fragment_tasks.xml code
  • The full TasksFragment.kt code
  • What happens when the code runs
  • Test Drive
  • TasksFragment needs to display records
  • Use getAll() to get all tasks from the database
  • A LiveData<List<Task>> is a more complex type
    • Use Transformations.map() to transform live data objects
  • Lets update the TasksViewModel code
  • Well bind the tasksString property to the layouts text view
    • We need to make the layout respond to live data updates
  • The full TasksFragment.kt code
  • What happens when the code runs
  • Test Drive
  • Mixed Messages
  • Mixed Messages Solution
  • Your Android Toolbox
• 15. Recycler Views: Reduce, Reuse, Recycle
  • What the Tasks app currently looks like
  • We can turn the list into a recycler view
  • Why use a recycler view?
    • Recycler views get their data from an adapter
  • Heres what were going to do
    • Add a recycler view dependency to the app build.gradle file
  • Tell the recycler view how to display each item
    • by defining a layout file
  • The adapter adds data to the recycler view
    • Create the adapter file
  • Tell the adapter what data it should work with
    • Override the getItemCount() method
  • Define the adapters view holder
  • Override the onCreateViewHolder() method
  • Add data to the layouts view
  • The full code for TaskItemAdapter.kt
  • The adapter code is complete
  • We need to display the recycler view
    • How to add a recycler view to a layout
  • The full code for fragment_tasks.xml
    • Tell the recycler view to use the adapter
  • The updated code for TasksFragment.kt
  • Weve added a recycler view to TasksFragments layout
    • Well make TasksFragment add task data to TaskItemAdapter
  • Update the TasksViewModel.kt code
  • TasksFragment needs to update TaskItemAdapters data property
  • The full code for TasksFragment.kt
    • Weve finished writing all the recycler view code
  • What happens when the code runs
  • Test Drive
  • Adapter Magnets
  • Adapter Magnets Solution
  • Recycler views are very flexible
  • Recycler view 2.0
    • Add a card view dependency to the app build.gradle file
  • How to create a card view
  • The full code for task_item.xml
  • The adapters view holder needs to work with the new layout code
  • The full code for TaskItemAdapter.kt
  • What the recycler view looks like so far
  • The layout manager gallery
    • Display items in a horizontal row
    • Use GridLayoutManager to display items in a grid
    • Arrange items in a staggered grid
  • Update fragment_tasks.xml to arrange items in a grid
  • What happens when the code runs
  • Test Drive
  • Pool Puzzle
  • Pool Puzzle Solution
  • Your Android Toolbox
• 16. Diffutil and Data Binding: Life in the Fast Lane
  • The recycler view displays task data correctly
    • but when the datas updated, the recycler view jumps
  • The Tasks app revisited
  • How the recycler view gets its data
  • The data propertys setter calls notifyDataSetChanged()
    • notifyDataSetChanged() redraws the entire list
  • Tell the recycler view what needs to change
    • DiffUtil works out differences between lists
  • Heres what were going to do
  • We need to implement DiffUtil.ItemCallback
    • Create TaskDiffItemCallback.kt
  • A ListAdapter accepts a DiffUtil.ItemCallback argument
    • We can simplify the rest of TaskItemAdapters code
  • The updated code for TaskItemAdapter.kt
  • Populate the ListAdapters list
    • using submitList()
  • The updated code for TasksFragment.kt
  • What happens when the code runs
  • Test Drive
  • BE the ListAdapter
  • Recycler views can use data binding
    • How well implement data binding
  • Add a data binding variable to task_item.xml
  • The layout gets inflated in the adapters view holder code
  • Use the binding class to inflate the layout
    • Set the layouts data binding variable to a Task
  • The full code for TaskItemAdapter.kt
    • Use data binding to set the layouts views
  • The full code for task_item.xml
  • What happens when the code runs
  • Test Drive
  • Adapter Magnets
  • Adapter Magnets Solution
  • BE the ListAdapter Solution
  • Your Android Toolbox
• 17. Recycler View Navigation: Pick a Card
  • Recycler views can be used for navigation
  • How the Tasks app is currently structured
  • Were going to make the recycler view navigate to a new fragment
  • Heres what were going to do
  • Make each item clickable
  • Where should we create the toast?
    • Well make TasksFragment pass the toast code in a lambda
  • How the code will work
  • The full code for TaskItemAdapter.kt
  • Well pass a lambda to TaskItemAdapter
  • The full code for TasksFragment.kt
  • What happens when the code runs
  • Test Drive
  • Adapter Magnets
  • Adapter Magnets Solution
  • We want to use the recycler view to navigate to a new fragment
  • Update the project build.gradle file
    • then update the app build.gradle file
  • Create EditTaskFragment
    • and create a navigation graph
  • Update the navigation graph
  • Add a NavHostFragment to MainActivitys layout
  • Make TasksFragment navigate to EditTaskFragment
  • Add a new property to TasksViewModel
    • Add methods to update the new property
  • The full code for TasksViewModel.kt
  • Make TasksFragment navigate to EditTaskFragment
    • Call onTaskClicked() when the user clicks a task
    • Navigate to EditTaskFragment when navigateToTask gets updated
  • The full code for TasksFragment.kt
  • Make EditTaskFragment display the task ID
    • We also need to update EditTaskFragment.kt
  • The full code for EditTaskFragment.kt
  • What happens when the code runs
  • Test Drive
  • We want to use EditTaskFragment to update task records
  • Use TaskDao to interact with database records
    • Well create a view model to access TaskDaos methods
  • Create EditTaskViewModel
    • The view model needs to get a task record
    • and include methods to update and delete the task
  • EditTaskViewModel will tell EditTaskFragment when to navigate
  • The full code for EditTaskViewModel.kt
  • EditTaskViewModel needs a view model factory
    • Create EditTaskViewModelFactory
  • fragment_edit_task.xml needs to display the task
    • We need to update EditTaskFragment.kt too
  • The full code for EditTaskFragment.kt
  • What happens when the code runs
  • Test Drive
  • Your Android Toolbox
• 18. Jetpack Compose: Compose Yourself
  • UI components dont have to be Views
    • Were going to build a Compose app
  • Heres what were going to do
  • Create a new Compose project
  • Configure the project
  • Compose projects have no layout files
  • What Compose activity code looks like
    • Compose activities extend ComponentActivity
  • Use a Text composable to display text
  • Use composables in composable functions
    • Call the Hello composable from setContent()
  • Most UIs have multiple composables
    • You can arrange composables using Row or Column
  • The full code for MainActivity.kt
  • Test Drive
  • You can preview composable functions
    • Add MainActivityPreview to MainActivity.kt
  • Preview composables with the Design or Split option
  • Pool Puzzle
  • Pool Puzzle Solution
  • Lets make the app convert temperatures
  • Add a MainActivityContent composable function
  • Display the header image
    • with an Image composable
  • Add an Image to MainActivity.kt
  • Lets display the temperature text
  • Test Drive
  • Use a Button composable to add a button
    • Lets write a ConvertButton composable function
  • We need to pass a lambda to ConvertButton
  • We need to change the value of TemperatureTexts argument
    • Use remember to store celsius in memory
  • The full code for MainActivity.kt
  • What happens when the app runs
  • Test Drive
  • Compose Magnets
  • Compose Magnets Solution
  • Let the user enter a temperature
    • Well use a TextField composable
  • Add a TextField to a composable function
    • Call the function in MainActivityContent
  • The full code for MainActivity.kt
  • What happens when the app runs
  • Test Drive
  • Well tweak the apps appearance
  • Add padding to the Column composable
  • You can center composables in Columns or Rows
    • Center all of a Columns content
    • Center the content of a single Row
  • Applying themes: revisited
    • How to apply a theme to composables
  • Android Studio includes extra theme code
    • How to apply the theme
  • The full code for MainActivity.kt
  • Test Drive
  • BE Compose
  • BE Compose Solution
  • Your Android Toolbox
• 19. Integrating Compose with views: Perfect Harmony
  • You can add composables to View-based UIs
    • The Guessing Game app revisited
  • The Guessing Game app structure
  • Heres what were going to do
  • Update the project build.gradle file
    • and update the app build.gradle file, too
  • Well replace ResultFragments views with composables
  • A ComposeView lets you add composables to a layout
    • Well add a ComposeView to fragment_result.xml
  • Add composables using Kotlin code
  • Add a composable function for the fragments content
  • Reproduce the Start New Game button
  • Reproduce ResultFragments TextView
  • The updated code for ResultFragment.kt
  • Test Drive
  • We need to remove ResultFragments views
    • and update ResultFragment.kt
  • onCreateView() returns the UIs root view
    • Return a ComposeView for Compose UIs
  • The full code for ResultFragment.kt
    • We can delete fragment_result.xml
  • What happens when the app runs
  • Test Drive
  • Pool Puzzle
  • Next well make GameFragment use composables too
  • Well add a ComposeView to fragment_game.xml
  • Add a composable function for GameFragments content
  • Reproduce the Finish Game button
  • Reproduce the EditText with a TextField
  • Reproduce the Guess button
  • The updated code for GameFragment.kt
  • Test Drive
  • Well display the incorrect guesses in a Text composable
    • Respond to LiveData using observeAsState()
  • Create an IncorrectGuessesText composable function
    • Run IncorrectGuessesText from GameFragmentContent
  • Compose Magnets
  • Compose Magnets Solution
  • The updated code for GameFragment.kt
  • Test Drive
  • Remove views from GameFragment.kt
  • Delete fragment_game.xml
    • We can also switch off data binding
  • Test Drive
  • Pool Puzzle Solution
  • Your Android Toolbox
  • Leaving town
  • Its been great having you here in Androidville
• A. Leftovers: The Top Ten Things (we didnt cover)
  • 1. Sharing data with other apps
    • Sharing data with Androids intent resolver
    • Sharing data with the Android Sharesheet
  • 2. WorkManager
    • Use WorkManager to schedule deferrable tasks
  • 3. Dialogs and notifications
    • Use dialogs to prompt the user for a decision
    • Notifications appear outside the apps UI
  • 4. Automated testing
    • Unit tests
    • Instrumented tests
    • An instrumented test example
  • 5. Supporting different screen sizes
    • Provide alternate layouts
    • Use a SlidingPaneLayout
  • 6. More Compose features
    • The Compose ViewModel library
    • Compose constraint layout library
    • The Compose Navigation component
  • 7. Retrofit
  • 8. Android Game Development Kit
  • 9. CameraX
  • 10. Publishing your app
    • Preparing your app for release
    • Releasing your app
• Index

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