The demand for new technologies and skilled developers is escalating in the midst of the ongoing digital transformation of the world. Modern lifestyles heavily rely on apps for a multitude of purposes, encompassing information retrieval, social connectivity, and daily tasks such as shopping, commuting, and bill management. Have you ever pondered the compensation that Android Developers receive for enabling these conveniences? According to PayScale, an Android Software Engineer’s annual salary in India is estimated at ₹3,99,594. To excel in interviews for both product and service-based companies, a strong grasp of the Top 10 Advanced Android Interview Questions is imperative.
In India, an experienced Android developer commands an average income of ₹13,16,973/-, reflecting the substantial rewards attainable in this field. The landscape varies when considering Android Developer Salaries on a global scale, with figures of $113,900 in the United States and £35,554 in the United Kingdom.
Prominent industry players such as Google, Amazon, Facebook, and burgeoning startups like Zomato, Paytm, and CRED are actively recruiting Android Developers. If your aspirations align with employment opportunities at these esteemed companies, immersing yourself in the top 10 Advanced Android Interview Questions and their corresponding answers can significantly enhance your interview performance.
Q1. What are the Lifecycle Events of an Android Activity?
The Android Lifecycle is a crucial component that provides insights into an activity or fragment’s current state. It offers a way for other objects to observe and react to these state changes. The Lifecycle class, along with Lifecycle Owner and Lifecycle Observer, forms the core of this architecture.
A. Lifecycle The Lifecycle class is instrumental in tracking the lifecycle events of an activity or fragment. It employs enumerations for States and Events, each event corresponding to a unique state. For example, OnCreate() is triggered when the activity is created, while OnStart() is called when it becomes visible to the user.
B. Lifecycle Owner Every Android activity has its own Lifecycle, and it serves as the Lifecycle Owner. The LifecycleOwner interface can be implemented by classes like Fragments and Activities, making them capable of maintaining their lifecycles. This enables the creation of unique LifecycleOwner components.
C. Lifecycle Observer The Lifecycle Observer, as the name suggests, observes the lifecycle of an activity or fragment. It records the state changes and responds accordingly. This observer’s behavior is linked to the lifecycle of the owning component. It’s a powerful tool for managing actions based on specific lifecycle events.
Q2. How would you communicate between Two Fragments?
In Android, efficient communication between fragments is essential. To ensure proper separation of concerns, direct communication between fragments should be avoided. Instead, a shared ViewModel or the related Activity can serve as the communication channel.
To facilitate communication, a shared ViewModel instance can be utilized. Both fragments can access this ViewModel through the hosting Activity. By exposing data via LiveData, the second fragment can receive updates whenever the data changes. This approach promotes data consistency and allows fragments to update the shared ViewModel.
Q3. What is a ViewHolder Pattern? Why should We use it?
The ViewHolder pattern is an optimization technique employed in Android’s RecyclerView, aimed at improving performance and reducing overhead. Unlike calling findViewById() for each item in a list, the ViewHolder pattern stores references to view elements, eliminating the need for repeated searches.
By using the ViewHolder pattern, the application’s efficiency increases significantly. The pattern ensures that view resources are referenced efficiently, preventing unnecessary lookups and contributing to smoother scrolling and better battery life.
Q4. What is the difference between Handler, AsyncTask, and Thread?
In Android, Handler, AsyncTask, and Thread are tools for managing concurrency and UI interactions.
Handler facilitates communication between background threads and the UI thread. It enables background threads to post messages to the UI thread’s message queue, ensuring safe UI updates.
AsyncTask simplifies managing asynchronous tasks by providing a concise way to run code in the background and update the UI. It also includes progress reporting and result handling.
Thread is a fundamental building block of multithreading. It allows you to execute tasks concurrently, but it lacks certain features like UI thread synchronization, thread pooling, and handling configuration changes.
Q5. Discuss Singletons vs Application Context for the app-global state.
While both Singletons and the Application Context can serve as app-global state management options, they have distinct characteristics.
Static Singletons can efficiently manage shared states across the application, but they can introduce complexities in testing and synchronization. On the other hand, the Application Context, maintained by the framework, offers a well-defined lifecycle and scope for managing app-global state.
Due to its clear lifecycle and scope, the Application Context is recommended for maintaining app-global state. Singletons, although powerful, should be used cautiously to avoid synchronization issues and unexpected side effects.
Q6. What is Android Jetpack Architecture Components?
Android Jetpack is a set of libraries, tools, and guidance provided by Google to enhance Android app development. It includes a collection of architecture components that assist in creating robust and maintainable apps.
These components include:
- Data Binding: Connecting data sources to UI elements declaratively.
- Lifecycles: Managing fragment and activity lifecycles, preventing memory leaks.
- LiveData: Notifying views about data changes in databases.
- Paging: Gradually loading data from data sources.
- Room: Mapping SQLite data to Java objects, providing compile-time checks.
- WorkManager: Managing background tasks under specific conditions.
Q7. What are some differences between Parcelable and Serializable?
Parcelable and Serializable are mechanisms for passing objects between components, but they differ in performance and implementation complexity.
Parcelable is optimized for Android and requires more effort to implement compared to Serializable. It offers better performance due to its explicit serialization procedure, making it faster than Serializable.
On the other hand, Serializable is simpler to implement but slower due to its use of reflection. Parcelable is more suitable for Android components like Intents, where performance is crucial, while Serializable is a more straightforward option for simpler cases.
Q8. What is Broadcast Receiver?
A Broadcast Receiver is a component in Android that allows apps to receive and respond to broadcast messages from other apps or the system. These messages can signal various events or system-level changes. Broadcast Receivers can handle two types of broadcasts: Normal Broadcasts and Ordered Broadcasts.
Q9. What is MVVM in Android?
The Model-View-ViewModel (MVVM) architecture is a design pattern that separates an Android app into distinct layers: Model, View, and ViewModel. This separation enhances maintainability and testability.
- Model: Represents the app’s data and business logic.
- View: Displays the UI elements and user interface.
- ViewModel: Acts as an intermediary between the Model and View, providing data and handling UI-related logic.
MVVM promotes a clear separation of concerns and improves code organization, making it easier to manage complex apps.
Q10. What is Android Jetpack?
Android Jetpack is a comprehensive suite of libraries, tools, and architectural guidance designed by Google to streamline Android app development. It comprises various components categorized into Foundation, Architecture, Behavior, and UI Components, which work together to create robust and efficient Android applications.
