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Questions and Answers
What is the primary purpose of using fragments in Android apps?
What is the primary purpose of using fragments in Android apps?
What does an Explicit Intent specify?
What does an Explicit Intent specify?
Which of the following is NOT a function of an Intent in Android?
Which of the following is NOT a function of an Intent in Android?
Which statement accurately describes an Implicit Intent?
Which statement accurately describes an Implicit Intent?
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What does lifecycle awareness refer to in the context of fragments?
What does lifecycle awareness refer to in the context of fragments?
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What is the primary purpose of Mobile App Architecture?
What is the primary purpose of Mobile App Architecture?
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Which architecture pattern is commonly used for Android apps?
Which architecture pattern is commonly used for Android apps?
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During which stage of the Android Activity Lifecycle is the Activity first created?
During which stage of the Android Activity Lifecycle is the Activity first created?
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What happens during the onPause() method of an Android Activity?
What happens during the onPause() method of an Android Activity?
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Which lifecycle method should be called to set up UI components after the Activity becomes visible?
Which lifecycle method should be called to set up UI components after the Activity becomes visible?
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What is the key role of the onResume() method in the Android Activity Lifecycle?
What is the key role of the onResume() method in the Android Activity Lifecycle?
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Which stage is NOT part of the Android Activity Lifecycle?
Which stage is NOT part of the Android Activity Lifecycle?
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What should occur during the onStart() method of an Android Activity?
What should occur during the onStart() method of an Android Activity?
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What is the primary purpose of the onStop() method in an Android Activity?
What is the primary purpose of the onStop() method in an Android Activity?
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Which method should be used to reinitialize resources that were released in onStop()?
Which method should be used to reinitialize resources that were released in onStop()?
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When is the onDestroy() method typically called?
When is the onDestroy() method typically called?
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What is the purpose of the line intent.putExtra("username", "JohnDoe");?
What is the purpose of the line intent.putExtra("username", "JohnDoe");?
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Which lifecycle method is called when an Activity is first created?
Which lifecycle method is called when an Activity is first created?
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What is the function of the onPause() method in the Android Activity lifecycle?
What is the function of the onPause() method in the Android Activity lifecycle?
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In the context of starting a new activity, what does startActivity(intent); do?
In the context of starting a new activity, what does startActivity(intent); do?
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In which scenario would onRestart() be called in an Android Activity?
In which scenario would onRestart() be called in an Android Activity?
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Which method is used to replace a fragment in the MainActivity?
Which method is used to replace a fragment in the MainActivity?
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What should be done in the onCreate() method of an Android Activity?
What should be done in the onCreate() method of an Android Activity?
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What will happen if savedInstanceState is not null in MainActivity?
What will happen if savedInstanceState is not null in MainActivity?
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What happens when detailsButton.setOnClickListener(v -> ... is called?
What happens when detailsButton.setOnClickListener(v -> ... is called?
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Which of the following statements about Activities in Android is FALSE?
Which of the following statements about Activities in Android is FALSE?
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How are data extras retrieved in the Second Activity?
How are data extras retrieved in the Second Activity?
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What does addToBackStack(null) do in the context of fragment transactions?
What does addToBackStack(null) do in the context of fragment transactions?
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What is the correct way to inflate a fragment view inside ListFragment?
What is the correct way to inflate a fragment view inside ListFragment?
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What is the primary role of an Activity in Android?
What is the primary role of an Activity in Android?
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Which method is called when an Activity is launched for the first time?
Which method is called when an Activity is launched for the first time?
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What does the onPause() method indicate in the Activity lifecycle?
What does the onPause() method indicate in the Activity lifecycle?
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What is the purpose of using Fragments in Android applications?
What is the purpose of using Fragments in Android applications?
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What happens during the onStop() method in the Activity lifecycle?
What happens during the onStop() method in the Activity lifecycle?
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How are Fragments integrated within an Activity?
How are Fragments integrated within an Activity?
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Which of the following best describes the Home Activity in an Android app?
Which of the following best describes the Home Activity in an Android app?
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Which of the following is NOT a lifecycle method of an Activity in Android?
Which of the following is NOT a lifecycle method of an Activity in Android?
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Study Notes
Mobile App Architecture
- Mobile app architecture is the structure of an app's core components, including data, presentation, and navigation.
Why Mobile App Architecture?
- Affects app performance, maintainability, and scalability.
- Platform differences, such as Android (MVVM or Clean Architecture) and iOS (MVC or MVVM), exist.
Android Activity Lifecycle
- Manages user interactions and resource handling, including pausing activities during interruptions (like phone calls).
Android Activity Lifecycle Stages and Methods
- onCreate(Bundle savedInstanceState): Called when an Activity is first created. Initializes the activity's UI, binds data, and initializes components.
-
onStart(): Called after
onCreateand displays the activity to the user, initiating actions like registering receivers and starting animations whenever the activity becomes visible. - onResume(): Called when the activity gains focus and becomes interactive, updating things like starting animations, refreshing UI, or updating data whenever the activity is active.
- onPause(): Called when the activity is partially blocked, like when a dialog appears or the user navigates away. Pauses updates, animations, or audio playback, saves data, and commits changes.
- onStop(): Called when the activity is no longer visible, often when the user opens a new activity.
-
onRestart(): Called if the activity is stopped and then restarted, such as when a user returns to it from the Recent Apps menu. Re-initializes any resources released in
onStop. - onDestroy(): Called before the activity is fully destroyed due to user or system-initiated actions. Cleans up remaining resources, ends background tasks, and performs any final state persistence.
Components of Android Apps - Activities
- An Activity is a single screen UI element, e.g., a news feed, editing a document, or navigating a map.
Purpose of Activities
- Displays user interfaces for interaction.
- Handles user input.
- Manages transitions between screens.
- Acts as an entry point to an app.
Activity Lifecycle (detailed steps)
- onCreate(): Called when the Activity is first created.
- onStart(): The Activity is visible to the user, but not yet fully in the foreground.
- onResume(): The Activity is interactive and in the foreground.
- onPause(): The Activity is about to lose focus.
- onStop(): The Activity is no longer visible.
- onDestroy(): The Activity is completely destroyed from memory.
Components of Android Apps - Fragments
- Fragments are reusable UI elements embedded within an Activity.
- They allow for modular design for reuse across various screens/sections of an app.
Purpose of Fragments
- Reusability
- Dynamic UI Design
- Simplified Navigation
- Lifecycle Awareness
Components of Android Apps - Intents
- Intents are abstract descriptions of actions/operations.
- Start new activities
- Start services (background)
- Send messages to other apps
- Pass data
Types of Intents
- Explicit Intent: Launches a specific component within the same app.
- Implicit Intent: Allows communication between different apps.
Passing Data Using Intents
- Use
putExtra()in the intents to carry data (e.g., String data).
Implementing Activities & Fragments in Android (Coding examples)
- Code examples demonstrate using Activities and Fragments to create Android applications, show content in layouts, etc.
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Description
This quiz explores the core components of mobile app architecture and its importance for performance and maintainability. It also covers the Android activity lifecycle stages and methods, detailing how they manage user interactions and resource handling.
