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Android Interview most asked coding questions

High-level and interview-ready advanced android set covering : Coding Questions (with logic & explanations) | 5+ Years / 10+ Years Advanced Android Questions | Android System Design (Real Interview Level)

By Skill to Growth

10 Jan 2026

Android Coding Interview Questions with practical explanation)

These questions focus on real coding logic. Interviewers ask these to check how you think, structure code, and handle real scenarios, not whether you remember definitions.

1. Reverse a String in Android (Java / Kotlin)

Question:
Write code to reverse a string.

Why interviewer asks this:
To check basic logic, string handling, and clean coding style.

Answer (Kotlin):

fun reverseString(input: String): String { return input.reversed() }

Human explanation:
In real apps, you rarely write such logic manually, but this checks your basics. Kotlin provides built-in functions, and interviewers like when you use them instead of overcomplicating things.

2. Check if a String is Palindrome

Question:
Check whether a given string is a palindrome.

Concept tested:
Loops, conditions, string comparison.

fun isPalindrome(text: String): Boolean { val cleanText = text.lowercase() return cleanText == cleanText.reversed() }

Real-world thinking:
Interviewers want to see clarity, not smart tricks. Clean code > complex logic.

3. Remove Duplicate Elements from a List

Question:
Remove duplicates from a list of integers.

fun removeDuplicates(list: List<Int>): List<Int> { return list.toSet().toList() }

Why this matters:
Android apps often deal with API data where duplicates appear. Knowing collections well is important.

4. Find the Largest Number in an Array

fun findMax(numbers: IntArray): Int { return numbers.maxOrNull() ?: 0 }

Interview expectation:
They check if you know standard library usage and null safety.

5. Handle Button Click Without Memory Leak

Question:
How do you handle click listeners safely?

button.setOnClickListener { // handle click }

Senior-level note:
In Fragments, always clear references in onDestroyView() to avoid leaks.

6. RecyclerView Adapter Basic Code

Question:
Write a simple RecyclerView adapter.

class MyAdapter(private val items: List) : RecyclerView.Adapter() { class ViewHolder(val view: View) : RecyclerView.ViewHolder(view) override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder { val view = LayoutInflater.from(parent.context) .inflate(android.R.layout.simple_list_item_1, parent, false) return ViewHolder(view) } override fun onBindViewHolder(holder: ViewHolder, position: Int) { (holder.view as TextView).text = items[position] } override fun getItemCount(): Int = items.size }

Why interviewer asks:
RecyclerView is unavoidable in Android jobs.

7. Difference Between == and equals()

Question:
Explain with code.

val a = "Android" val b = "Android" println(a == b) // true (content check) println(a === b) // false or true (reference check)

Important:
Kotlin uses == for content equality — very common interview trap.

8. API Call Using Retrofit (Basic)

interface ApiService { @GET("users") suspend fun getUsers(): List }

What they check:
Do you know modern Android (Retrofit + Coroutines)?

9. Coroutine vs Thread (Coding Perspective)

lifecycleScope.launch { val data = api.getUsers() }

Explanation:
Coroutines are lightweight and lifecycle-aware — perfect for Android.

10. Pass Data Between Activities

val intent = Intent(this, DetailActivity::class.java) intent.putExtra("name", "Android") startActivity(intent)

Explanation:
How would you handle null safety while receiving data?

11. Handle Configuration Changes with ViewModel

class MyViewModel : ViewModel() { val counter = MutableLiveData(0) }

Why this matters:
Interviewers want to see if you understand rotation problems.

12. Validate Email Input

fun isValidEmail(email: String): Boolean { return android.util.Patterns.EMAIL_ADDRESS.matcher(email).matches() } 

13. Find Even Numbers from List

fun getEvenNumbers(list: List<Int>): List<Int> { return list.filter { it % 2 == 0 } }

Explanation:
Functional programming knowledge.

14. Lazy Initialization Example

val userName: String by lazy { "Android Developer" }

Explanation:
Memory optimization and Kotlin basics.

15. Handle Null Safety in Kotlin

val name: String? = null println(name ?: "Default")

Very important for interviews.

16. Background Task Using WorkManager

val workRequest = OneTimeWorkRequestBuilder().build() WorkManager.getInstance(context).enqueue(workRequest)

Explanation:
Checks background task handling knowledge.

17. Detect Network Connectivity

val connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager 

18. Sort a List Alphabetically

val names = listOf("Android", "Kotlin", "Java") val sorted = names.sorted()

19. Prevent Multiple Button Clicks

button.isEnabled = false 

20. Memory Leak Prevention (Code Level)

Question:
How do you avoid memory leaks?

🔸 Use ViewBinding properly
🔸 Clear references in Fragment
🔸 Avoid static Context
🔸 Use LeakCanary

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Welcome to Skill to Growth - technology-focused learning blog, created for developers who want to build strong, real-world skills and grow confidently in their careers. I started this blog with one clear mission: to make learning technology simple, practical, and career-oriented for anyone who truly wants to grow. In a world full of scattered tutorials and half-explained concepts, this platform is built to give you clarity, structure, and confidence. This blog covers Android development, Flutter, React Native, Spring Boot, DevOps, and Git, designed carefully from absolute beginner to industry-ready level. Every topic here is written with the mindset of real-world application, not just theory. I believe that learning should not feel confusing or intimidating. That’s why each article focuses on strong fundamentals, clean explanations, and step-by-step learning paths that actually make sense. If you are a student starting from zero, this blog helps you build a solid foundation. If you are a working professional, it helps you upgrade your skills, stay relevant, and move ahead in your career. You’ll learn how to build mobile applications, create powerful backend systems, manage code using Git, and deploy applications using modern DevOps practices. More importantly, you’ll understand how everything connects, so you think like a complete developer—not just a coder. This platform is for those who are serious about their growth, who want more than just copy-paste tutorials. It’s for learners who want confidence in interviews, clarity in projects, and stability in their careers. Technology changes fast, but strong fundamentals and the right mindset never go out of date. This blog exists to help you build both. If you’re ready to invest in yourself, stay consistent, and learn the right way— you’re in the right place.
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