60+ Interview Question

Q32. Have you worked on MVVM?

Ans. Yes, I have worked on MVVM architecture pattern.

• MVVM stands for Model-View-ViewModel.

• It separates the UI logic from the business logic.

• ViewModel acts as a mediator between Model and View.

• Data binding is a key feature of MVVM.

• I have implemented MVVM in my previous Android projects using Android Architecture Components such as LiveData and ViewModel.

Q33. What is a Broadcast Receiver?

Ans. Broadcast Receiver is a component of Android system that listens to system-wide broadcast announcements.

• It is used to respond to system-wide broadcast announcements.

• It is implemented as a subclass of BroadcastReceiver class.

• It can be registered either statically in AndroidManifest.xml or dynamically in code.

• Examples of system-wide broadcasts are battery low, network connectivity changes, etc.

Q34. Write a recursive function to reverse a string.

Ans. Recursion can be used to reverse a string by breaking it down into smaller parts until the base case is reached.

• Base Case: If the string is empty or has one character, return it as is.

• Recursive Case: Take the last character and append it to the result of reversing the substring excluding the last character.

Q35. Your last projects.describe tools used for coding

Ans. I have used Android Studio, Git, JIRA, and Slack for coding in my last projects.

• Android Studio for development

• Git for version control

• JIRA for project management

• Slack for team communication

Q36. What is the Fibonacci series?

Ans. The Fibonacci series is a sequence of numbers where each number is the sum of the two preceding ones.

• The series starts with 0 and 1, and each subsequent number is the sum of the two preceding numbers.

• The Fibonacci series: 0, 1, 1, 2, 3, 5, 8, 13, 21, ...

• It is a common mathematical sequence used in various algorithms and applications.

Q37. What is AAPT?

Ans. AAPT stands for Android Asset Packaging Tool. It is used to package and compile Android app resources.

• AAPT is a command-line tool that is included in the Android SDK.

• It is used to compile resources such as images, layouts, and strings into a binary format that can be used by the Android system.

• AAPT also generates the R.java file, which contains references to all the resources in an Android app.

• It can be used to package an app's resources into an APK file for distribution.

• AAPT can be used to validate and debug Android app resources.

Q38. What is RxJava?

Ans. RxJava is a library for composing asynchronous and event-based programs using observable sequences.

• RxJava is a Java implementation of ReactiveX, a library for composing asynchronous and event-based programs using observable sequences.

• It provides a set of operators to transform, filter, and combine these sequences.

• RxJava can be used for network calls, database operations, UI events, and more.

• It simplifies concurrency and makes code more readable and maintainable.

• Example: Observable.just(1, 2, 3).map(i -> i * 2).subscribe(System.out::println);

Q39. What are the key differences between Java and C++?

Ans. Java is an object-oriented programming language while C++ is a hybrid language that supports both procedural and object-oriented programming.

• Java is platform-independent while C++ is platform-dependent.

• Java has automatic garbage collection while C++ requires manual memory management.

• Java has a simpler syntax compared to C++.

• Java does not support pointers while C++ does.

• Java has a built-in exception handling mechanism while C++ requires manual exception handling.

• Java is used for developing Android apps while C++ is used for developing system software, games, and high-performance applications.

Q40. Write the output of the given left join.

Ans. The output of a left join operation.

• A left join returns all the rows from the left table and the matching rows from the right table.

• If there is no match, NULL values are returned for the right table columns.

• The output will have all the columns from the left table and the matching columns from the right table.

Q41. What is Jetpack Compose?

Ans. Jetpack Compose is a modern Android UI toolkit for building native UIs using a declarative approach.

• Jetpack Compose allows developers to build UI components using a Kotlin-based DSL.

• It simplifies UI development by enabling a reactive programming model.

• Composable functions in Jetpack Compose are used to define UI elements.

• It offers a more efficient way to create dynamic and interactive user interfaces.

• Jetpack Compose is part of the Jetpack suite of libraries provided by Google for Android development.

Q42. Explain the perfect singleton design pattern.

Ans. Perfect singleton design pattern ensures only one instance of a class is created and provides a global point of access to it.

• Private constructor to prevent direct instantiation

• Private static instance variable

• Public static method to access the instance

• Lazy initialization to create the instance only when needed

• Thread-safe implementation to prevent multiple instances in a multi-threaded environment

Q43. How to work with school

Ans. Working with school requires communication, planning, and flexibility.

• Establish clear communication channels with school staff

• Plan ahead for deadlines and events

• Be flexible and adaptable to changes in schedule or curriculum

• Collaborate with teachers and administrators to support student success

Q44. What is WorkManager?

Ans. Work Manager is an Android Jetpack library used for managing deferrable, asynchronous tasks.

• Work Manager is part of the Android Jetpack library.

• It is used for managing deferrable, asynchronous tasks that need to run even if the app is in the background.

• Work Manager provides various constraints and options for scheduling tasks, such as network availability, charging status, and more.

• It is recommended for tasks that are not time-critical and can be deferred to run at a later time.

• Work Manager is a good choice for tasks like syncing data, uploading logs, and periodic tasks.

Q45. Given a list of strings, how would you implement a search function?

Ans. Use a loop to search for a specific string in an array of strings.

• Iterate through each string in the array

• Use a conditional statement to check if the current string matches the search string

• Return the index of the matching string or -1 if not found

Q46. What do you know about Android?

Ans. Android is an operating system developed by Google for mobile devices.

• Android is based on the Linux kernel.

• It provides a framework for building mobile applications.

• Android applications are written in Java or Kotlin programming languages.

• Android supports a wide range of hardware devices and screen sizes.

• Google Play Store is the official app store for Android applications.

Q47. Explain the activity lifecycle.

Ans. Activity life cycle refers to the stages an activity goes through from creation to destruction.

• An activity is created using onCreate() method

• It becomes visible using onStart() method

• It becomes interactive using onResume() method

• It goes to background using onPause() method

• It becomes invisible using onStop() method

• It gets destroyed using onDestroy() method

Q48. Explain MVVM in detail

Ans. MVVM is a design pattern that separates UI code from business logic and data handling.

• MVVM stands for Model-View-ViewModel

• Model represents the data and business logic

• View displays the UI and user interactions

• ViewModel acts as a mediator between Model and View

• ViewModel exposes data and commands to the View

• Data binding is used to keep the View and ViewModel in sync

• MVVM promotes testability and maintainability of code

Q49. Life Cycle Of android activity

Ans. The life cycle of an Android activity refers to the different states an activity goes through during its lifetime.

• onCreate() is called when the activity is first created

• onStart() is called when the activity becomes visible to the user

• onResume() is called when the activity starts interacting with the user

• onPause() is called when the activity is partially obscured by another activity

• onStop() is called when the activity is no longer visible to the user

• onDestroy() is called when the activity is being destroyed

Q50. What skills are important for an Android developer?

Ans. An Android developer should have knowledge of Java, Android SDK, and experience in developing mobile applications.

• Proficiency in Java programming language

• Familiarity with Android SDK and Android Studio

• Experience in developing mobile applications

• Knowledge of RESTful APIs and JSON

• Understanding of Material Design guidelines

• Ability to work with third-party libraries and APIs

• Debugging and problem-solving skills

• Knowledge of version control systems like Git

Q51. Describe architectural design patterns.

Ans. MVC (Model-View-Controller) architecture design pattern separates an application into three main components.

• Model: Represents the data and business logic of the application

• View: Represents the UI components of the application

• Controller: Acts as an intermediary between Model and View, handling user input and updating the Model accordingly

Q52. What is context?

Ans. Context is an object that provides access to application-specific resources and classes.

• Context is used to access resources like databases, preferences, etc.

• It is required for creating views, starting activities, and accessing system services.

• Examples include accessing strings from resources, launching activities, and creating intents.

Q53. Can you provide a Java thread code example?

Ans. Java threads allow concurrent execution of multiple parts of a program.

• Threads are created by extending the Thread class or implementing the Runnable interface

• Threads can be started using the start() method

• Thread.sleep() can be used to pause a thread for a specified amount of time

• Synchronization can be used to prevent multiple threads from accessing shared resources simultaneously

Q54. What is an intent?

Ans. Intent is a messaging object used to request an action from another app component.

• Intent is used to start activities, services, and broadcast receivers in Android.

• It can also be used to pass data between components.

• There are two types of intents: explicit intents and implicit intents.

• Explicit intents specify the component to start by name.

• Implicit intents specify the action to perform and let the system find the appropriate component to handle it.

Q55. How does OOP work?

Ans. OOPs is a programming paradigm that uses objects to represent real-world entities and their interactions.

• OOPs stands for Object-Oriented Programming.

• It is based on the concept of classes and objects.

• Encapsulation, inheritance, and polymorphism are the three main pillars of OOPs.

• Encapsulation is the process of hiding the implementation details of an object from the outside world.

• Inheritance allows a class to inherit properties and methods from another class.

• Polymorphism allows objects of different classes to be treated as if they are of the same class.

• Java and C++ are two popular programming languages that support OOPs.

Q56. Scope functions in kotlin

Ans. Scope functions in Kotlin are functions that allow you to execute a block of code within the context of an object.

• There are five scope functions in Kotlin: let, run, with, apply, and also.

• Each scope function has a specific use case and can help improve code readability and reduce boilerplate code.

• Scope functions can be used to perform operations on an object and return a result or modify the object itself.

• For example, 'apply' is commonly used for initializing objects, while 'let' is used for null-checking and transforming objects.

Q57. What are the differences between LazyRow and RecyclerView?

Ans. LazyRow is a Jetpack Compose component for displaying horizontally scrolling lists, while RecyclerView is a traditional Android view for displaying large data sets efficiently.

• LazyRow is part of Jetpack Compose, RecyclerView is part of the Android framework

• LazyRow is more declarative and easier to use for simple lists, RecyclerView is more powerful and customizable for complex lists

• LazyRow automatically handles recycling of items, RecyclerView requires manual implementation of view recycling

Q58. MVVM Pattern in android

Ans. MVVM is a design pattern used in Android development to separate the UI logic from the business logic.

• MVVM stands for Model-View-ViewModel

• Model represents the data and business logic

• View is the UI component that displays the data

• ViewModel acts as a mediator between the Model and View, handling the UI logic and data manipulation

• MVVM helps in maintaining a clean and organized codebase

Q59. Define the various types of errors.

Ans. Various types of errors include syntax errors, logical errors, and runtime errors.

• Syntax errors occur when code violates the rules of the programming language.

• Logical errors occur when code does not produce the expected output due to flawed logic.

• Runtime errors occur when code encounters an unexpected condition during execution.

• Other types of errors include semantic errors, input/output errors, and network errors.

Q60. How would you implement an LRU cache?

Ans. Leu cache is a caching mechanism that improves performance by storing frequently accessed data in memory.

• Leu cache is based on the Least Recently Used (LRU) eviction policy.

• It stores key-value pairs, where keys are unique identifiers for data.

• Example: In an Android app, caching images can reduce loading times.

• Leu cache can be implemented using libraries like LruCache in Android.

• It helps in reducing network calls by storing previously fetched data.

Q61. Explain the concept of view binding.

Ans. View binding simplifies UI interactions in Android by providing type-safe access to views.

• View binding is enabled in the build.gradle file: 'android { viewBinding { enabled = true } }'

• It generates a binding class for each XML layout file, e.g., 'ActivityMainBinding' for 'activity_main.xml'.

• Access views directly using the binding object, e.g., 'binding.textView.setText('Hello World!')'.

• No need for 'findViewById', reducing boilerplate code and potential null pointer exceptions.

• View binding works with both fragments and activities, enhancing code readability and maintainability.