ROKI Senior Software Engineer Interview Questions and Answers

Q1. Jave oops concepts, overloading vs overriding, hash map internal implementation, java 8 features, stream api
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Q2. Java related questions, more on project related topics
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Write a code to fill the water tank

Q1. How to measure slope of random voltage waveform?
Ans. 
The slope of a random voltage waveform can be measured by calculating the rate of change of voltage over time.
• Calculate the difference in voltage between two points on the waveform

• Divide the voltage difference by the time interval between the two points to get the slope

• Repeat this process for multiple points on the waveform to get an average slope
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Q2. Design a circuit for Water Tank Filling
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Design a circuit for Water Tank Filling
• Use a float switch to detect water level in the tank

• Connect the float switch to a relay to control the water flow

• Include a solenoid valve to regulate the water flow

• Use a microcontroller to monitor the water level and control the relay and solenoid valve
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Q1. Python and sql questions
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Q1. Client interview
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Q1. General discussion
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Q1. System design round about ott
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Q2. Leetcode rain water problem
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Q1. A scenario to create a new Android service
Ans. 
Creating a new Android service
• Define a class that extends Service class

• Override onStartCommand() method to handle service logic

• Register the service in AndroidManifest.xml file
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Q2. 2 puzzles. one was to find min no of weighs to find faulty item among 8 items and the other one was to min no of races required to find top three horses among 25 horses
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Q3. How to manage gralloc buffers
Ans. 
Managing gralloc buffers involves allocating, locking, and freeing memory for graphics rendering in Android.
• Allocate gralloc buffer using gralloc_alloc() function

• Lock buffer for reading or writing using gralloc_lock() function

• Free buffer using gralloc_free() function

• Example: gralloc_alloc(usage, width, height, format, &handle)

• Example: gralloc_lock(handle, usage, left, top, width, height, &vaddr)
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Q4. What is HIDL vs AIDL
Ans. 
HIDL stands for Hardware Interface Definition Language and is used for communication between HAL and framework. AIDL stands for Android Interface Definition Language and is used for inter-process communication in Android.
• HIDL is used for communication between Hardware Abstraction Layer (HAL) and framework in Android

• AIDL is used for inter-process communication in Android

• HIDL is more efficient and faster than AIDL
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Q5. How Android buffers are passed from application to drivers.
Ans. 
Android buffers are passed from application to drivers through shared memory and buffer queues.
• Android applications communicate with drivers through the HAL (Hardware Abstraction Layer)

• Buffers are typically passed using shared memory regions

• Buffer queues are used to manage the flow of data between application and driver

• Example: Camera application passing image data to camera driver for processing
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Q6. What happens if LINUX faces a hardware interrupt
Ans. 
When LINUX faces a hardware interrupt, it stops executing the current code and jumps to a specific interrupt handler.
• LINUX stops executing the current code and jumps to a specific interrupt handler

• The interrupt handler processes the interrupt and resumes normal execution afterwards

• Different hardware interrupts are handled by different interrupt handlers
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Q7. What is the challenge while creating multiple services in Android
Ans. 
The challenge while creating multiple services in Android is managing communication between services and ensuring proper synchronization.
• Managing communication between services can be complex and error-prone.

• Ensuring proper synchronization between services to avoid race conditions and data inconsistencies.

• Handling dependencies between services and coordinating their interactions.

• Testing and debugging multiple services ...read more
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Q8. Boot up Android sequence
Ans. 
The Android boot up sequence involves several stages including power on, bootloader, kernel initialization, system server startup, and app launch.
• Power on the device

• Bootloader loads the Android OS kernel

• Kernel initializes the system and drivers

• System server starts up and launches essential services

• Apps are launched and user interface becomes accessible
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Q9. Describe about Permission files/SE Linux policy
Ans. 
Permission files/SE Linux policy control access to resources based on rules set by administrators.
• Permission files define who can access a file or directory and what actions they can perform.

• SE Linux policy is a security mechanism that enforces rules on how processes interact with resources.

• SE Linux policy is based on labels assigned to processes and resources, determining access permissions.

• SE Linux policy can be cust...read more
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Q10. What is manifestation file and how is it used?
Ans. 
A manifestation file is a configuration file used to define the properties and settings of a software application.
• Manifestation files typically include information such as the application's name, version, dependencies, and permissions.

• They are commonly used in software development to ensure that the application runs correctly and has access to necessary resources.

• Examples of manifestation files include AndroidManifest....read more
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C++, DSA, 3 hours should have good knowledge of data structure and algorithms

Q1. 1. Find the max 3 items in a unsorted array
Ans. 
Find the max 3 items in an unsorted array of strings.
• Sort the array in descending order.

• Return the first 3 elements of the sorted array.
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It was a graph coloring problem.

Q1. Chessboard knight problem
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Q1. No one joined the interview from interview panel and it happened twice to which HR after ignoring my mails/call for long told me that since team works from Korea they don't get time. She was having very c...read more
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