Android Interview Questions and Answers
Android Interview Questions and Answers - Your Cheat Sheet For Android Interview
Prepared and maintained by the Founder of Outcome School: Amit Shekhar
About me
Hi, I am Amit Shekhar, Founder @ Outcome School • IIT 2010-14 • I have taught and mentored many developers, and their efforts landed them high-paying tech jobs, helped many tech companies in solving their unique problems, and created many open-source libraries being used by top companies. I am passionate about sharing knowledge through open-source, blogs, and videos.
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Live session on "Android Developer Interview Preparation for Product-based Companies"
I conducted a live session on "Android Developer Interview Preparation for Product-based Companies"
Interacted with over 500 Android Developers.
Guided, motivated, and inspired them to aim higher and achieve more.
Recording Link: https://www.youtube.com/watch?v=Yby0AA7ZSUE
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Contents - Android Interview Questions
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Android Interview Questions and Answers Playlist
Watch this video on "Android Developer Interview Preparation for Product-Based Companies": Android Developer Interview Preparation for Product-Based Companies
- Question: Android Push Notification Flow using FCM
- Question: What is an inline function in Kotlin?
- Question: What is the advantage of using const in Kotlin?
- Question: What is a reified keyword in Kotlin?
- Question: Suspending vs Blocking in Kotlin Coroutines
- Question: Retrofit vs OkHttp
- Question: Launch vs Async in Kotlin Coroutines
- Question: internal visibility modifier in Kotlin
- Question: open keyword in Kotlin
- Question: lateinit vs lazy in Kotlin
- Question: What is Multidex in Android?
- Question: How does the Android Push Notification system work?
- Question: How does the Kotlin Multiplatform work?
- Question: What is a ViewModel and how is it useful?
- Question: Is it possible to force the Garbage Collection in Android?
- Question: What is a JvmStatic Annotation in Kotlin?
- Question: init block in Kotlin
- Question: JvmField Annotation in Kotlin
- Question: singleTask launchMode in Android
- Question: Difference between == and === in Kotlin
- Question: JvmOverloads Annotation in Kotlin
- Question: Why is it recommended to use only the default constructor to create a Fragment?
- Question: Why do we need to call setContentView() in onCreate() of Activity class?
- Question: When only onDestroy is called for an activity without onPause() and onStop()?
Kotlin Coroutines
Topics you should know in Kotlin Coroutines for Android Interview:
- coroutines
- suspend
- launch, async-await, withContext
- dispatchers
- scope, context, job
- lifecycleScope, viewModelScope, GlobalScope
- suspendCoroutine, suspendCancellableCoroutine
- coroutineScope, supervisorScope
- runBlocking
- Exception Handling
Learn the above-mentioned from the following links:
Kotlin Flow API
Topics you should know in Kotlin Flow API for Android Interview:
- Flow Builder, Operator, Collector
- flowOn, dispatchers
- Operators such as filter, map, zip, flatMapConcat, retry, debounce, distinctUntilChanged, flatMapLatest
- Terminal operators
- Cold Flow vs Hot Flow
- StateFlow, SharedFlow, callbackFlow, channelFlow
Learn the above-mentioned from the following links:
Kotlin
Android Interview Questions and Answers:
Android
Android Interview Questions and Answers:
Base
Activity and Fragment
Why is it recommended to use only the default constructor to create a Fragment? - Learn from video and blog
What is Activity and its lifecycle? - Learn from here
What is the difference between onCreate() and onStart() - Learn from here
When only onDestroy is called for an activity without onPause() and onStop()? - Learn from here
Why do we need to call setContentView() in onCreate() of Activity class? - Learn from here
What is onSaveInstanceState() and onRestoreInstanceState() in activity? - Learn from here
What is Fragment and its lifecycle? - Learn from here
What is Bundle in Android? - Learn from here
What are "launchMode"? - Learn from here and singleTask launchMode in Android
What is the difference between a Fragment and an Activity? Explain the relationship between the two. - Learn from here
When should you use a Fragment rather than an Activity?
- When you have some UI components to be used across various activities
- When multiple views can be displayed side by side just like ViewPager
What is the difference between FragmentPagerAdapter vs FragmentStatePagerAdapter?
- FragmentPagerAdapter: Each fragment visited by the user will be stored in the memory but the view will be destroyed. When the page is revisited, then the view will be created not the instance of the fragment.
- FragmentStatePagerAdapter: Here, the fragment instance will be destroyed when it is not visible to the user, except the saved state of the fragment.
What is the difference between adding/replacing fragment in backstack? - Learn from here
How would you communicate between two Fragments?
What is retained Fragment? - Learn from here
What is the purpose of addToBackStack() while commiting fragment transaction?
- By calling addToBackStack(), the replace transaction is saved to the back stack so the user can reverse the transaction and bring back the previous fragment by pressing the Back button. For more Learn from here
Views and ViewGroups
Optimizing layouts in Android - Learn from here
What is View in Android?
Difference between View.GONE and View.INVISIBLE? - Learn from here
Can you a create custom view? How?
What are ViewGroups and how they are different from the Views?
- View: View objects are the basic building blocks of User Interface(UI) elements in Android. View is a simple rectangle box which responds to the user’s actions. Examples are EditText, Button, CheckBox etc. View refers to the android.view.View class, which is the base class of all UI classes.
- ViewGroup: ViewGroup is the invisible container. It holds View and ViewGroup. For example, LinearLayout is the ViewGroup that contains Button(View), and other Layouts also. ViewGroup is the base class for Layouts.
What is a Canvas? - Learn from here
What is a SurfaceView? - Learn from here
Relative Layout vs Linear Layout.
Tell about Constraint Layout optimization - Learn from here
Do you know what is the view tree? How can you optimize its depth? - Learn from here
Displaying Lists of Content
What is the difference between ListView and RecyclerView? - Learn from here
How does the RecyclerView work? - Learn from here
RecyclerView Optimization - Scrolling Performance Improvement - Learn from here
Optimizing Nested RecyclerView - Learn from here
How does RecyclerView improve performance over ListView?
What are the components of a RecyclerView?
Explain the role of RecyclerView.Adapter and RecyclerView.ViewHolder - Learn from here
What is a LayoutManager in RecyclerView?
How do you handle multiple view types in a single RecyclerView?
What is DiffUtil and how does it improve RecyclerView performance? - Learn from here
What is the purpose of RecyclerView.setHasFixedSize(true)? - Learn from here
How do you update a specific item in RecyclerView?
What is SnapHelper? - Learn from here: SnapHelper
Dialogs and Toasts
Intents and Broadcasting
What is Intent? - Learn from here
What is an Implicit Intent? - Learn from here
What is an Explicit Intent? - Learn from here
What is a BroadcastReceiver? - Learn from here
Describe how broadcasts and intents work to be able to pass messages around your app? - Learn from here
What is a PendingIntent?
- If you want someone to perform any Intent operation at future point of time on behalf of you, then we will use Pending Intent.
What are the different types of Broadcasts? - Learn from here
Services
Inter-process Communication
How can two distinct Android apps interact? - Learn from here
Is it possible to run an Android app in multiple processes? How? - Learn from here
What is AIDL? Enumerate the steps in creating a bounded service through AIDL. - Learn from here
What can you use for background processing in Android? - Learn from here
What is a ContentProvider and what is it typically used for? - Learn from here
Long-running Operations
Working With Multimedia Content
Data Saving
Jetpack DataStore Preferences - Learn from here
Persisting Data in an Android App - Learn from here
What is ORM? How does it work?
How would you preserve the Activity state during a screen rotation? - Learn from here
What are different ways to store data in your Android app? - Learn from here
Explain Scoped Storage in Android.
How to encrypt data in Android?
What is commit() and apply() in SharedPreferences?
- commit() returns a boolean value of success or failure immediately by writing data synchronously.
- apply() is asynchronous and it won't return any boolean response. If you have an apply() outstanding and you are performing commit(), then the commit() will be blocked until the apply() is not completed.
Look and Feel
What is a Spannable?
What is a SpannableString?
- A SpannableString has immutable text, but its span information is mutable. Use a SpannableString when your text doesn't need to be changed but the styling does. Spans are ranges over the text that include styling information like color, highlighting, italics, links, etc
What are the best practices for using text in Android?
How to implement Dark mode in any application?
Memory Optimizations
Improve Android App Performance - Learn from here
What is the onTrimMemory() method? - Learn from here
How to identify and fix OutOfMemory issues?
How do you find memory leaks in Android applications?
Battery Life Optimizations
Supporting Different Screen Sizes
Permissions
- What are the different protection levels in permission?
Native Programming
Android System Internal
Android Jetpack
Others
Android Libraries
Android Interview Questions and Answers:
Android Architecture
Android Interview Questions and Answers:
Design Pattern
Android Interview Questions and Answers
Android System Design
Android Interview Questions and Answers:
Refer to this blog: Android System Design Interviews
Android Unit Testing
Android Interview Questions and Answers:
Android Interview Questions and Answers:
Jetpack Compose
Topics you should know in Jetpack Compose for Android Interview:
- Compose
- State: remember, rememberSaveable, MutableState
- Recomposition
- State hoisting
- Side-effects
- Modifier
- Theme
- Layout, List
- Gestures, Animation
- CompositionLocal
- Phases
Learn the above-mentioned from the following links:
Questions
Jetpack Compose vs Android View System
Explain the concept of declarative UI in Jetpack Compose.
Declarative UI vs Imperative UI
What are Composable functions?
What is Recomposition?
What is State in Compose?
How does state management work in Jetpack Compose?
Stateful composable vs Stateless composable
What are the side effects?
Difference between LaunchedEffect and DisposableEffect.
What is rememberCoroutineScope and its use cases?
How to observe Flows, and LiveData states in Compose UI?
How can we handle asynchronous operations in Jetpack Compose?
How can we convert a non-compose state into a Compose state?
Explain derivedStateOf.
Explain rememberUpdatedState.
Difference between remember and rememberSaveable. - Learn from here
Explain the Lifecycle of a Composable in Jetpack Compose.
How do you handle lifecycle events in Compose functions?
What are the best practices for performance optimization in Jetpack Compose?
Can we use both Jetpack Compose and Android View in a Single App?
What is State Hoisting?
Explain CompositionLocal
Explain Jetpack Compose Phases. - Learn from here
What is the role of the Modifier in Jetpack Compose?
What are Semantics?
How can you handle user input and events in Jetpack Compose?
How do you handle navigation in Jetpack Compose?
How do you handle orientation changes in Jetpack Compose?
Explain the concept of unidirectional data flow in Jetpack Compose.
How to create Custom Layouts in Compose?
Java
Android Interview Questions and Answers:
Solid Principles
- “S” in SOLID Principles: The Single Responsibility Principle - Learn from here
- "O" in SOLID Principles: Open/Closed Principle - Learn from here
- “L” in SOLID Principles: Liskov Substitution Principle (LSP) - Learn from here
- “I” in SOLID Principles: Interface Segregation Principle (ISP) - Learn from here
- “D” in SOLID Principles: Dependency Inversion Principle (DIP) - Learn from here
OOP
Explain OOP Concepts.
Differences between abstract classes and interfaces?
- An abstract class, is a class that contains both concrete and abstract methods
(methods without implementations). An abstract method must be implemented by the abstract class
sub-classes. Abstract classes cannot be instantiated and need to be extended to be used.
- An interface is like a blueprint/contract of a class (or it may be thought of as a class with methods, but without their implementation). It contains empty methods that
represent, what all of its subclasses should have in common. The subclasses provide the
implementation for each of these methods. Interfaces are implemented.
Difference between method overloading and overriding.
Explain "String Pool" in Java - Learn from here
What are the access modifiers you know? What does each one do?
- There are four access modifiers in Java language (from strictest to the most lenient):
private variables, methods, constructors or inner classes are only visible to its' containing class and its' methods. This modifier is most commonly used, for example, to allow variable access only through getters and setters or to hide underlying implementation of classes that should not be used by user and therefore maintain encapsulation. Singleton constructor is also marked private to avoid unwanted instantiation from outside.Default (no keyword is used) this modifier can be applied to classes, variables, constructors and methods and allows access from classes and methods inside the same package.protected can be used on variables, methods and constructors therefore allowing access only to subclasses and classes that are inside the same package as protected members' class.public modifier is widely-used on classes, variables, constructors and methods to grant access from any class and method anywhere. It should not be used everywhere as it implies that data marked with public is not sensitive and can not be used to harm the program.
Can an Interface implement another Interface?
- Yes, an interface can implement another interface (and more than one), but it needs to use
extends, rather than implements keyword. And while you can not remove methods from parent interface, you can add new ones freely to your sub-interface.
What is Polymorphism? What about Inheritance?
Collections and Generics
Objects and Primitives
How is String class implemented? Why was it made immutable?
There is no primitive variant of String class in Java language - all strings are just wrappers around underlying array of characters, which is declared final. This means that, once a String object is instantiated, it cannot be changed through normal tools of the language (Reflection still can mess things up horribly, because in Java no object is truly immutable). This is why String variables in classes are the first candidates to be used, when you want to override hashCode() and equals() of your class - you can be sure, that all their required contracts will be satisfied.
Note: The String class is immutable, so that once it is created a String object cannot be changed. The String class has a number of methods, some of which will be discussed below, that appear to modify strings. Since strings are immutable, what these methods really do is create and return a new string that contains the result of the operation. (Official Java Documentation)
This class is also unique in a sense, that, when you create an instance like this:
String helloWorld = "Hello, World!";
"Hello, World!" is called a literal and compiler creates a String object with its' value. So
String capital = "Hello, World!".toUpperCase();
is a valid statement, that, firstly, will create an object with literal value "Hello, World!" and then will create and return another object with value "HELLO, WORLD!"
String was made immutable to prevent malicious manipulation of data, when, for example, user login or other sensitive data is being send to a server.
What does it means to say that a String is immutable?
- It means that once created,
String object's char[] (its' containing value) is declared final and, therefore, it can not be changed during runtime.
Can you list 8 primitive types in java?
byteshortintlongfloatdoublecharboolean
What is the difference between an Integer and int?
int is a primitive data type (with boolean, byte, char, short, long, float and double), while Integer (with Boolean, Byte, Character, Short,Long, Float and Double) is a wrapper class that encapsulates primitive data type, while providing useful methods to perform different tasks with it.
Do objects get passed by reference or value in Java? Elaborate on that.
Java Memory Model and Garbage Collector
Concurrency
What does the keyword synchronized mean?
What is a ThreadPoolExecutor? - ThreadPoolExecutor in Android
What is volatile modifier?
Object Level Lock vs Class Level Lock in Java - Learn from here
Concurrency vs Parallelism - Learn from here
The classes in the atomic package expose a common set of methods: get, set,, lazyset, compareAndSet, and weakCompareAndSet. Please describe them.
Exceptions
How does the try{}, catch{}, finally works?
What is the difference between a Checked Exception and an Un-Checked Exception?
Others
Shallow vs. Deep Copy in Java - Learn from here
Explain Serialization and Deserialization - Learn from here
What is serialization? How do you implement it?
What is transient modifier?
What are anonymous classes?
What is the difference between using == and .equals on an object?
What is the hashCode() and equals() used for?
When would you make an object value final?
What are these final, finally and finalize keywords?
What is the difference between "throw" and "throws" keyword in Java?
throws is just used to indicated which exception is to be thrown. But the throw keyword is used to throw some exception from any static block or any method.
What does the static word mean in Java?
- In case of
static variable it means that this variable (its' value or the object it references) spans across all instances of enclosing class (changing it in one instance affects all others), while in case of static methods it means that these methods can be invoked without an instance of their enclosing class. It is useful, for example, when you create util classes that need not be instantiated every time you want to use them.
Can a static method be overridden in Java?
- While child class can override a static method with another static method with the same signature (return type can be down-casted), it is not truly overridden - it becomes "hidden", but both methods can still be accessed under right circumstances (see question about overloading/overriding above).
When is a static block run?
- Code inside static block is executed only once: the first time you make an object of that class or the first time you access a static member of that class (even if you never make an object of that class).
Explain Reflection in Java - Learn from here
What is Dependency Injection?
Difference between StringBuffer and StringBuilder? - Learn from here
What is the difference between fail-fast and fail-safe iterators in Java?
Monitor and Synchronization
Other Topics
Android Interview Questions and Answers:
Data Structures and Algorithms
- Android Developer should know these Data Structures for Next Interview - Check here
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License
Copyright (C) 2025 Amit Shekhar
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
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这是一个规模很大的 Android 面试题集，收录了问题与答案，涵盖 Kotlin、Kotlin 协程、Kotlin Flow、Android 基础、架构、设计模式、系统设计、单元测试和 Java。