Google Android Developer Interview Questions and Answers

Q1. What is the difference between interface and abstract class?
Ans. 
Interface defines only method signatures while abstract class can have both method signatures and implementations.
• An interface can be implemented by multiple classes while a class can only extend one abstract class.

• An abstract class can have constructors while an interface cannot.

• An abstract class can have non-abstract methods while an interface can only have abstract methods.

• An abstract class can have instance variabl...read more
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Q2. What is singleton class?
Ans. 
A singleton class is a class that can only have one instance created at a time.
• Singleton classes are often used for managing resources that should only have one instance, such as a database connection or a configuration file.

• They are implemented by making the constructor private and providing a static method to access the single instance.

• Singleton classes can also implement interfaces and inherit from other classes.

• Exa...read more
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Q1. Structs vs Classes
Ans. 
Structs are value types and passed by value, while classes are reference types and passed by reference.
• Structs are used for small, simple data types like coordinates or colors.

• Classes are used for more complex data types that require inheritance or reference semantics.

• Structs are copied when passed around, while classes are passed by reference.

• Structs are stack allocated, while classes are heap allocated.
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Q2. Discussion about design patterns
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Q3. OOPS discussion
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Q4. Concurrency discussion
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Data structure - tree and linkedlist questions asked, binary search tree

Q1. Java multithreading
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Q2. Write code for synchronise threads
Ans. 
Synchronizing threads in Android can be achieved using synchronization blocks or methods.
• Use synchronized keyword to create a synchronized block or method

• Use locks such as ReentrantLock for more complex synchronization needs

• Consider using synchronized collections like ConcurrentHashMap for thread-safe data structures
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Q1. Explain the concept of multithreading and how is it differ from multiprocessing
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Multithreading allows multiple threads to exist within the context of a single process, while multiprocessing involves multiple processes running concurrently.
• Multithreading allows multiple threads to share the same memory space and resources of a single process, while multiprocessing involves separate memory space for each process.

• Multithreading is more lightweight and efficient compared to multiprocessing as threads ...read more
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Q1. View Model Scope for activity or fragment
Ans. 
View Model Scope determines whether a ViewModel should be scoped to an activity or a fragment.
• View Model scoped to activity: shared between all fragments within the activity

• View Model scoped to fragment: specific to that fragment only

• Use activity scope for data shared across fragments, fragment scope for fragment-specific data
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Q1. Android Memory Leaks
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Q2. Android architecture
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Q3. Kotlin basics questions
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Q1. Questions related to kotlin coroutines in depth questions, scenario based questions
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Q2. Solid principles
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Q3. Architecture patterns
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Q4. Kotlin coroutine
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Q5. Unit testing, espresso scenario based
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Q1. Desing pattern and ui testing
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Q2. Design pattern and coding
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Q3. Make api flow and create with help of design pattern for ui and ux testing
Ans. 
The answer to the question is provided below.
• To create an API flow, start by identifying the endpoints and their functionalities.

• Design the UI and UX testing by using appropriate design patterns like MVC or MVVM.

• Implement the API calls and handle the responses using networking libraries like Alamofire.

• Use XCTest or UI Testing frameworks for automated UI and UX testing.

• Mock the API responses for testing purposes using t...read more
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