Intro to Android Development
  • Welcome
  • Syllabus
  • Hack Challenge
  • Resources
    • Lecture Videos
    • Ed Discussion
    • Git & GitHub Help/How-To
    • Setting up Android Studio
    • Starting an Android Studio Project & Making an Emulator
    • Importing, Exporting, & Submitting Your Projects to CMS
  • SP25 Course Material
    • Week 1 | Course Logistics, Kotlin, & Basic UI
      • Relevant Links
      • Demo/Lecture: Eatery Card
      • A0: Eatery Card (Follow-Along)
    • Week 2 | States, Components, LazyColumn
      • Relevant Links
      • Demo: Todo List
      • A2: Shopping List
    • Week 3 | Navigation & Animations
      • Relevant Links
      • Demo: Onboarding
      • A3: Stock Trading (RobbingGood)
    • Week 4 | MVVM and Flows
      • Relevant Links
      • Demo: Eatery Card 2
      • A4: Chat of a Lifetime
    • Week 5 | Dumb Components & UIEvents
      • Relevant Links
      • Demo: Music Player
      • A5: Rate My Vibe
    • Week 6 | Coroutines, Networking, JSON
      • Relevant Links
      • Demo: Retrofit
      • A6: You Should Even Lift, Bro.
  • Bonus Week | Android Job Search
    • Relevant Links
    • Android Technical Interview Question!
  • Textbook
    • 1. Introduction to the Editor and Views
      • 1.1 Introduction to the Editor
      • 1.2 SDK Management
      • 1.3 Kotlin Overview
      • 1.4 Views
      • 1.5 Android Studio Project Demo + Understanding The Editor
    • 2. Jetpack Compose
      • 2.1 Introduction
      • 2.2 Layouts
      • 2.3 Modifiers
      • 2.4 Animations
      • 2.5 Lazy Lists
      • 2.6 Reactive UI
    • 3. Intents and Manifest
      • 3.1 Activities
      • 3.2 Implicit Intents
      • 3.3 Explicit Intents
      • 3.4 Manifest
      • 3.5 Permissions
      • 3.6 Summary
    • 4. Navigation
      • 4.1 Types of Navigation
      • 4.2 Implementation of the Bottom Navigation Bar
    • 5. Data and Persistent Storage
      • 5.1 Singleton Classes
      • 5.2 Shared Preferences
      • 5.3 Rooms
      • 5.4 Entities
      • 5.5 Data Access Objects
      • 5.6 Databases
    • 5.5 Concurrency
      • 5.5.1 Coroutines
      • 5.5.2 Implementation of Coroutines
      • 5.5.3 Coroutines with Networking Calls
    • 6. Networking and 3rd Party libraries
      • 6.1 HTTP Overview
      • 6.2 3rd Party Libraries
      • 6.3 JSON and Moshi
      • 6.4 Retrofit
      • 6.5 Summary
    • 7. MVVM Design Pattern
      • 7.1 Key Idea
      • 7.2 Implementation Ideas
    • 8. Flows
    • 9. The Art and Ontology of Software
    • 10. 🔥 Firebase
      • 10.1 Setting up Firebase
      • 10.2 Authentication
      • 10.3 Analytics
      • 10.4 Messaging
      • 10.5 Firestore
  • Additional Topics
    • Git and GitHub
    • Exporting to APK
  • Archive
    • Archived Native Android Textbook Pages
      • 1. Layouts and More Views
        • 1.1 File Structure and File Types
        • 1.2 Resource Files
        • 1.3 Button and Input Control
        • 1.4 ViewGroups
        • 1.5 Summary + A Note On Chapter 2 Topics
      • 2. RecyclerViews
        • 2.1 RecyclerViews
        • 2.2 RecyclerView Performance
        • 2.3 Implementation of a Recycler View
        • 2.4 Implementation with Input Controls
        • 2.5 Filtering RecyclerViews
        • 2.6 Recyclerview Demo
      • 3. ListViews and Searching
        • 3.1 ListView vs. RecyclerView
        • 3.2 ListView Performance
        • 3.3 Implementation of a ListView
        • 3.4 Searching in a List View
      • 4. Fragments
        • 4.1 What are Fragments?
        • 4.2 Lifecycle of a Fragment
        • 4.3 Integrating a Fragment into an Activity
        • 4.4 Sharing Data Between Fragments
        • 4.5 Fragment Slide Shows
      • 5. OkHttp
      • 6. Activity Lifecycle
      • 7. Implementation of Tab Layout
    • Fall 2024 Course Material
      • Lecture 1 & Exercise 1: Introduction to Android
      • Lecture 1.5: Beauty of Kotlin
      • Lecture 2 & HW 2: Modifiers, Lazylists and Reactive UI
      • Lecture 3 & HW 3: Animations, Intents and Manifest
      • Lecture 4 & HW 4: Coroutines & Navigation
      • Lecture 5 & HW 5: Persistent Storage, Networking, and JSON Parsing
      • Lecture 6 & HW 6: MVVM, Flows
      • Bonus Lectures & Bonus HW
      • Bonus Lecture: Industry Practice
    • Spring 2024 Course Material
      • Lecture 1 & Exercise 1: Introduction to Android
      • Lecture 4 & HW 4: LazyLists
      • Lecture 6 & HW 6: Networking, Data, and Persistent Storage
    • Spring 2020 Course Material
      • Week 1: Intro to the Editor
      • Week 2: Views and Layouts
      • Week 3: Intent and Manifest
      • Week 4: ListView and RecyclerView
      • Week 5: Fragments
      • Week 6: Networking
    • Spring 2021 Lecture & HW 8: Networking & 3rd Party APIs
    • HackOurCampus Workshop
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  1. Archive
  2. Archived Native Android Textbook Pages
  3. 4. Fragments

4.1 What are Fragments?

Previous4. FragmentsNext4.2 Lifecycle of a Fragment

Last updated 7 months ago

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Say you have a complex activity that receives many different forms of user input and displays many different things to the user, like Facebook’s home screen. For these screens, fragments are used to divide up the activity into parts that are easier to work with.

Fragments are similar to activities in that each fragment has its own lifecycle methods (ie. onCreate(), onResume()) and has a unique layout file associated with it. However, unlike Activities, fragments don’t need to be declared in AndroidManifest.xml; instead, they must be attached to a larger activity.

Fragments are also often used to quickly change subsections of the screen while keeping other parts intact. For example, in Eatery, we have one main activity with three fragments (one for each tab).

Although it may seem like we are completely transitioning screens, there is only one activity (MainActivity.kt) that was used in creation of these displays. You’ll notice that the toolbar and the bottom navigation bar does not change as you switch tabs. This is because the toolbar and bottom navigation bar are created in MainActivity.kt.

Inside the main activity, we added a layout for displaying the different fragments, which exists between the toolbar and the bottom navigation bar. When the user switches the tab, the corresponding fragment is swapped in.