InnovationM Senior Android Developer Interview Questions, Process, and Tips

Q1. What are the different android components and concepts such as Recycler View, View Model, ANR and how do they function internally?
Ans. 
Android components like Recycler View, View Model, ANR are essential for building robust Android applications.
• Recycler View: Efficient way to display large data sets by recycling views as they scroll off the screen.

• View Model: Manages UI-related data in a lifecycle-conscious way, surviving configuration changes.

• ANR (Application Not Responding): Dialog shown to the user when the main thread of an app is blocked for too ...read more
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Q2. How will you debug and solve the following crash and ANR from the given stack trace?
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Q3. Solve this DSA question.
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Q1. Similar questions to the first round.
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Q1. Implement an LRU cache
Ans. 
LRU cache is a data structure that stores the most recently used items, discarding the least recently used items when full.
• Use a hashmap to store key-value pairs for quick access

• Use a doubly linked list to keep track of the order of items based on their usage

• When an item is accessed, move it to the front of the list

• When the cache is full, remove the least recently used item from the end of the list
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Q1. Basic OOPs questions
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Q2. Questions on my project, what is the current project I am working on, my role in that
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Q3. Life cycle questions
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Q1. Android related questions
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Q2. One DSA question
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Q1. About previous projects
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Q2. About technology used in previous projects
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Q1. Activity life cycle Factorial and fabbonacci series lateiniti var vs lazy Var vs val
Ans. 
Activity life cycle is a crucial concept in Android development. Factorial and Fibonacci series are common mathematical problems. lateinit var and lazy are used for initializing variables. Var and val are used for declaring variables.
• Activity life cycle includes methods like onCreate, onStart, onResume, onPause, onStop, onDestroy.

• Factorial is the product of all positive integers up to a given number. Example: 5! = 5*4*...read more
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There were total 3 rounds and it consists of Basic array and string coding question

Round duration - 60 minutes
Round difficulty - Easy

This was a DSA based round, I was asked to code on collabedit.

Q1. Rearrange Linked List
You have been given a singly Linked List in the form of 'L1' -> 'L2' -> 'L3' -> ... 'Ln'. Your task is to rearrange the nodes of this list to ...read more
Ans. 
A simple approach to do this is to sort the linked list using merge sort and then swap alternate nodes.
Time Complexity : O(nlogn)
The efficient approach would be to traverse the given linked list and check if current node maintains the zigzag order or not. 
To check if the given node maintains zigzag order or not, a variable ind is used. 
If ind = 0, then the current node’s data should be less than its adjacent ...read more
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Q2. Find Missing Number In String
You had a sequence of consecutive nonnegative integers. You appended all integers at the end of each other to form a string ‘S’ without any separators. While appending each in...read more
Ans. 
XOR approach can be used to solve this question in an efficient manner. The following property of XOR can be used :
1. If x1^x2^…xn = a and x1^x2^..xn-1 = b , then a^b = xn
Steps:
1. Declare two variables a= 0 and b = 0
2. Calculate the xor of numbers from 1 to n and store them in a i.e. 1^2^…n = a. 
3. Now traverse the array from start to end.
4. For every index i update b as b = b ^ arr[i]
5. Return the missing number ...read more
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Q3. Palindrome Permutation
You are given a string 'S', check if there exists any permutation of the given string that is a palindrome.
Note :
1. A palindrome is a word or phrase that reads the same ...read more
Ans. 
A set of characters can form a palindrome if at most one character occurs odd number of times and all characters occur even number of times.

This can be done in O(n) time using a count array. 
Steps : 
1. Create a count array of alphabet size which is typically 256. Initialize all values of count array as 0.
2. Traverse the given string and increment count of every character.
3. Traverse the count array and if the...read more
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Round duration - 30 minutes
Round difficulty - Medium

This was onsite interview round 1. Java and Android threading concepts are needed.

Q1. Java Question
What is Cyclic Barrier?
Ans. 
A CyclicBarrier is a synchronizer that allows a set of threads to wait for each other to reach a common execution point, also called a barrier. CyclicBarriers are used in programs in which we have a fixed number of threads that must wait for each other to reach a common point before continuing execution. The barrier is called cyclic because it can be re-used after the waiting threads are released.
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Q2. Android Question
What are the different launch modes for activities?
Ans. 
1.Standard : This is the default launch mode of activity (If not specified). It launches a new instance of an activity in the task from which it was launched. Numerous instances of the activity can be generated, and multiple instances of the activity can be assigned to the same or separate tasks. 
Syntax: 

2.Single Task : In this method of operation, a new task is always generated, and a new instance is added t...read more
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Q3. Technical Question
How to pass a simple Java object from one thread to another?
Ans. 
One way could be to create an implementation of Runnable that is constructed with the array of doubles and then pass it into a thread pool executor.

Example : 
public class MyDoublesProcessor implements Runnable {
double[] doublesArray;
public MyDoublesProcessor(double[] array) {
doublesArray = array;
}

public void run() {
//do stuff with array
}
}

Executor exec = Executors.newFixedThreadPool(1);

void callback(double[] array)...read more
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Round duration - 60 minutes
Round difficulty - Easy

This round was all about android and internals of collections in Java.

Q1. Android Question
What is IntentService?
Ans. 
IntentService is an extension of the Service component class that handles asynchronous requests (expressed as Intents) on demand. Clients send requests through Context.startService(Intent) calls; the service is started as needed, handles each Intent in turn using a worker thread, and stops itself when it runs out of work.
This "work queue processor" pattern is commonly used to offload tasks from an application's main th...read more
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Q2. Android Question
Difference between deep links and app links?
Ans. 
A deep link is an intent filter system that allows users to directly enter a specific activity in an Android app. However there is an issue about this process. When a user click an URL, it might open a dialog which asks the user to select one of multiple apps handling the given URL.
On the other hand, An Android App Link is a deep link based on your website URL that has been verified to belong to your website. When user
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Q3. Android Question
What are the IPC mechanisms available in android OS?
Ans. 
1) Intents are messages which components can send and receive. It is a universal mechanism of passing data between processes. With help of the intents one can start services or activities, invoke broadcast receivers and so on.

2) Bundles are entities of data that is passed through. It is similar to the serialization of an object, but much faster on android. Bundle can be read from intent via the getExtras() method.

3) Bi...read more
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Round duration - 90 minutes
Round difficulty - Medium

Technical interview round for purely checking the design knowledge of a person.

Q1. Android Question
Design an photo viewing app which will show images from the disk in the list, and one item in the list should take half of the screen.
Ans. 
Tip 1: Before you jump into the solution always clarify all the assumptions you’re making at the beginning of the interview. Ask questions to identify the scope of the system. This will clear the initial doubt, and you will get to know what are the specific detail interviewer wants to consider in this service.
Tip 2: Design your structure and functions according to the requirements and try to convey your thoughts proper...read more
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Q2. LRU Cache Implementation
Design and implement a data structure for Least Recently Used (LRU) cache to support the foll...read more
Ans. 
Structure of an LRU Cache :

1) In practice, LRU cache is a kind of Queue — if an element is reaccessed, it goes to the end of the eviction order
2) This queue will have a specific capacity as the cache has a limited size. Whenever a new element is brought in, it is added at the head of the queue. When eviction happens, it happens from the tail of the queue.
3) Hitting data in the cache must be done in constant time, which...read more
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Q3. Android Question
Design a weather app. (One image for every weather is there on a server) Take care of half downloaded image, try not to consume data of user again.
Ans. 
Tip 1: Before you jump into the solution always clarify all the assumptions you’re making at the beginning of the interview. Ask questions to identify the scope of the system. This will clear the initial doubt, and you will get to know what are the specific detail interviewer wants to consider in this service.
Tip 2: Design your structure and functions according to the requirements and try to convey your thoughts proper...read more
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Q4. Android Question
Design the ImageDownloader, with efficiently handling parallel API calls
Ans. 
Tip 1: Before you jump into the solution always clarify all the assumptions you’re making at the beginning of the interview. Ask questions to identify the scope of the system. This will clear the initial doubt, and you will get to know what are the specific detail interviewer wants to consider in this service.
Tip 2: Design your structure and functions according to the requirements and try to convey your thoughts proper...read more
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Round duration - 30 minutes
Round difficulty - Easy

This was the last Interview with director of engineering.

Q1. Basic HR Questions
Q1. What were your challenges you faced in your project work?
Q2. Which project you loved most and which one you did not ?
Ans. 
Tip 1 : The cross questioning can go intense some time, think before you speak.
Tip 2 : Be open minded and answer whatever you are thinking. 
Tip 3 : Since everybody in the interview panel is from tech background, here too you can expect some technical questions. No coding in most of the cases but some discussions over the design can surely happen.
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