BlackBerry Software Engineer Level 1 Interview Questions and Answers

1. Reversing a linked list.
2. Find all substrings in a string.

Q1. Oops Concepts, DBMS, Array Manipulation, Design Patterns.
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Q2. System Design- Design an online food delivery platform
Ans. 
Design an online food delivery platform
• Identify target audience and their needs

• Create a user-friendly interface for ordering food

• Develop a robust backend system for managing orders and deliveries

• Partner with local restaurants to offer a wide variety of cuisines

• Implement a payment gateway for secure transactions

• Provide real-time order tracking for customers

• Ensure food safety and quality through proper packaging and deli...read more
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Q1. Technical Interview + Coding
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Q1. Technical Interview
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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
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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
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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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Q1. Python related questions
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Q1. Behavioral and management
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