Android Performance Optimization and Memory Management Quiz Quiz

Challenge your understanding of Android performance techniques and effective memory management. This quiz covers best practices, key concepts, and real-world scenarios to help improve app efficiency and reduce memory issues in Android development.

1. Avoiding Memory Leaks

   Which method best helps to prevent memory leaks when using long-running tasks in Android activities?

   1. Store context in a static variable
   2. Use only global variables
   3. Use WeakReference for activity context
   4. Declare variables as public

   Explanation: Using WeakReference for the activity context ensures that the garbage collector can reclaim memory when the activity is destroyed, helping to prevent memory leaks. Declaring variables as public does not address memory management. Storing context in a static variable keeps the reference alive and prevents proper garbage collection, increasing leak risk. Using only global variables is unrelated to leak prevention and often exacerbates memory issues.

2. Efficient Image Loading

   When displaying a large image from storage in an Android app, how can you optimize memory usage?

   1. Load the image at full resolution
   2. Increase the heap size
   3. Downsample the image before loading
   4. Store all images in static variables

   Explanation: Downsampling the image before loading reduces its resolution and therefore the amount of memory required. Loading images at full resolution can quickly exhaust available memory and cause crashes. Storing all images in static variables leads to memory retention and possible leaks. Increasing heap size is not a practical or preferred solution; optimizing image size is more efficient.

3. Garbage Collection Triggers

   Which action is most likely to trigger garbage collection during your Android app's runtime?

   1. Switching between light and dark mode
   2. Applying a theme change
   3. Allocating a large number of new objects rapidly
   4. Opening the options menu

   Explanation: Rapidly allocating new objects can quickly consume available memory, prompting the system to run garbage collection to reclaim space. Opening the options menu and switching UI themes use standard operations but are unlikely by themselves to trigger garbage collection unless accompanied by significant memory allocation. Applying a theme change typically affects appearance but is not a direct cause of object allocation.

4. Thread Safety in UI Updates

   In Android, why should you avoid updating the user interface directly from a background thread?

   1. It improves battery consumption
   2. Background threads have higher priority
   3. Only services can update the UI
   4. UI updates must run on the main thread

   Explanation: UI updates must run on the main (UI) thread in Android to avoid unpredictable behavior and crashes. Background threads do not have higher priority than the main thread for UI changes. Services can execute code in the background but are not exclusively allowed to update the UI. Updating the UI from background threads does not improve battery consumption and is not recommended.

5. Best Practice with Caching

   What is considered best practice for caching large lists of data to improve performance in Android applications?

   1. Write repeatedly to internal storage
   2. Save to global variables
   3. Store in static lists
   4. Use a memory-efficient cache like LruCache

   Explanation: Using a memory-efficient cache such as LruCache automatically manages memory and removes the least recently used items, helping balance speed and memory usage. Saving data to global variables or static lists retains objects in memory longer than needed, increasing memory consumption risk. Writing data repeatedly to internal storage is slow and not efficient for high-performance caching.

6. Reducing Battery Drain

   How can limiting the frequency of background location updates improve an Android app's performance?

   1. It improves background music quality
   2. It reduces excessive CPU and memory usage
   3. It increases the number of background notifications
   4. It always reduces app startup time

   Explanation: Reducing the frequency of background location updates conserves CPU and memory, decreasing battery drain and resource use. It does not affect music playback quality, as that's unrelated to location updates. Increasing background notifications could further consume resources, not save them. Location update frequency has little to no impact on app startup time.

7. Avoiding Excessive Object Creation

   Why is creating unnecessary objects inside the onDraw method of a custom Android view discouraged?

   1. It avoids null pointer errors
   2. It accelerates GPU processing
   3. It disables hardware acceleration
   4. It increases memory allocation and slows rendering

   Explanation: Creating objects inside the onDraw method causes frequent memory allocations during every frame, resulting in sluggish rendering and possible frame drops. Accelerating GPU processing is unrelated; new objects do not speed up graphics processing. Avoiding null pointer errors depends on code logic, not object creation frequency. Hardware acceleration is managed outside object creation practices.

8. Managing Background Tasks

   Which approach helps avoid memory leaks when running background tasks in Android components that may be destroyed, such as activities or fragments?

   1. Keep a static reference to the component
   2. Always use synchronous background tasks
   3. Ignore the lifecycle of the component
   4. Cancel background tasks when the component is destroyed

   Explanation: Canceling background tasks when their associated component is destroyed ensures no lingering references and prevents memory leaks. Maintaining a static reference keeps the component alive unnecessarily, causing leaks. Ignoring the lifecycle of components misses key cleanup points. Always using synchronous tasks can block the UI and cause performance issues.

9. Memory Analysis Tools

   When experiencing unexplained memory growth in your Android app, which tool can you use to identify potential memory leaks?

   1. A code formatter
   2. A memory profiler
   3. A layout inspector
   4. A style editor

   Explanation: A memory profiler tracks memory allocation and identifies leaks by pinpointing where memory is not released. A layout inspector allows for debugging user interface layouts, not memory. A style editor helps with appearance customization but not memory tracking. A code formatter adjusts code style, offering no insights into memory usage.

10. Optimizing RecyclerView Performance

    Which is an effective way to improve performance and reduce memory usage with RecyclerView in an Android app?

    1. Inflate new item views each time
    2. Use static lists for data
    3. Reuse and recycle view holders
    4. Avoid using adapters

    Explanation: Reusing and recycling view holders minimizes view creation and reduces memory use, which is the core advantage of RecyclerView. Inflating new views for every item is inefficient and wasteful. Using static lists can create memory retention issues. Adapters are essential to managing view binding in RecyclerView; avoiding them is not recommended.