600+ Application Developer Interview Questions and Answers

Optimize loading of 15kg and 25kg bags in a truck with a max weight of 1000kg and a bag difference limit of 4.

• Let x be the number of 15kg bags and y be the number of 25kg bags.

• The equations to consider are: 15x + 25y ≤ 1000 and |x - y| ≤ 4.

• To maximize the load, we can test combinations of x and y within the constraints.

• Example: If x = 36 and y = 32, then 15(36) + 25(32) = 540 + 800 = 1340 (exceeds limit).

• Example: If x = 40 and y = 36, then 15(40) + 25(36) = 600 + 900 = 1500 (...read more

Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.

• Abstract class can have constructors, member variables, and methods, while interface cannot have any of these.

• A class can extend only one abstract class but can implement multiple interfaces.

• Abstract classes are used to provide a common base for subclasses, while interfaces are used to define a contract for classes to implement.

• Example: Abstract class - Animal with a...read more

Adding a new feature using SOLID principles

• Identify the new feature and its requirements

• Analyze the existing codebase and identify areas that need modification

• Apply SOLID principles to design the new feature

• Implement the feature using clean code practices

• Test the feature thoroughly to ensure it meets the requirements

To get distinct data without using distinct keyword, use GROUP BY clause.

• Use GROUP BY clause with the column name to group the data by that column.

• Use aggregate functions like COUNT, SUM, AVG, etc. to get the desired result.

• Example: SELECT column_name FROM table_name GROUP BY column_name;

• Example: SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name;

Implementing a sorting algorithm in Java to arrange an array of numbers in ascending order.

• Use Arrays.sort() method for simplicity: Example: int[] numbers = {5, 3, 8}; Arrays.sort(numbers); // Result: {3, 5, 8}

• Implement Bubble Sort for educational purposes: Iterate through the array, swapping adjacent elements if they are in the wrong order.

• Consider Quick Sort for efficiency: Divide the array into sub-arrays and sort them recursively.

• Use Merge Sort for a stable sorting algori...read more

Data from an Excel sheet can be brought into Databricks using the read method in Databricks.

• Use the read method in Databricks to read the Excel file.

• Specify the file path and format (e.g. 'xlsx') when using the read method.

• Transform the data as needed using Databricks functions and libraries.

• Example: df = spark.read.format('com.crealytics.spark.excel').option('useHeader', 'true').load('file.xlsx')

Dynamic allocation of memory to 2D array is done using double pointer and malloc function.

• Declare a double pointer to hold the 2D array.

• Allocate memory to the first dimension using malloc function.

• Allocate memory to the second dimension using a loop and malloc function.

• Free the memory after use to avoid memory leaks.

• Example: int **arr; arr = (int **)malloc(rows * sizeof(int *));

• Example: for(int i=0; i

I have knowledge on various devops tools and have worked on challenging use cases such as implementing continuous integration and deployment pipelines using Jenkins and Docker.

• Proficient in using Jenkins, Docker, Git, Ansible, and Kubernetes

• Implemented CI/CD pipelines for multiple projects

• Automated deployment process using Ansible and Kubernetes

• Implemented containerization using Docker and Kubernetes

• Implemented infrastructure as code using Terraform

• Challenging use case: Setti...read more

ConcurrentHashMap is a thread-safe implementation of the Map interface in Java.

• ConcurrentHashMap allows multiple threads to read and write to the map concurrently without causing any inconsistencies.

• It achieves thread-safety by dividing the map into segments, each of which can be locked independently.

• ConcurrentHashMap uses a technique called lock striping to minimize contention and improve performance.

• It does not throw ConcurrentModificationException during iteration as it wo...read more

Overloading is when multiple methods have the same name but different parameters. Overriding is when a subclass provides a different implementation of a method inherited from its superclass.

• Overloading allows a class to have multiple methods with the same name but different parameters.

• Overriding occurs when a subclass provides a different implementation of a method inherited from its superclass.

• Overloading is resolved at compile-time based on the method signature.

• Overriding i...read more

Multitasking involves executing multiple tasks simultaneously, while multiprogramming involves running multiple programs on a single processor.

• Multitasking allows multiple tasks to run concurrently, switching between them quickly.

• Multiprogramming involves loading multiple programs into memory and executing them concurrently.

• Examples of multitasking include running multiple applications on a computer or a smartphone.

• Examples of multiprogramming include running multiple instanc...read more

Mutex is used for exclusive access to a resource, while semaphore is used for controlling access to a resource by multiple threads.

• Mutex is binary and allows only one thread to access the resource at a time.

• Semaphore can have a count greater than one, allowing multiple threads to access the resource simultaneously.

• Mutex is used for protecting critical sections of code, while semaphore is used for synchronization between threads.

• Example: Mutex is like a key to a room that only...read more

Undo operation (ctrl + z) is implemented by maintaining a stack of previous states.

• When a change is made, the current state is pushed onto the stack

• When undo is called, the top state is popped and applied

• Redo is implemented by maintaining a stack of undone states

• Some applications may also implement a limit on the number of undo/redo steps

• Undo/redo can be implemented at different levels (e.g. character, word, paragraph)

Creating a pointer for an abstract class and pointing it to a derived class object with a function name conflict.

• Use virtual keyword for the function in the abstract class.

• Use override keyword for the function in the derived class.

• Access the function using the pointer with the derived class object.

To find the middle element of a linked list in a single traversal.

• Use two pointers, one moving at twice the speed of the other.

• When the faster pointer reaches the end, the slower pointer will be at the middle.

• If the linked list has even number of elements, the middle will be the second of the two middle elements.

UNION removes duplicates while UNION ALL does not

• UNION combines result sets and removes duplicates

• UNION ALL combines result sets without removing duplicates

• UNION is slower than UNION ALL as it involves removing duplicates

• Use UNION when you want to remove duplicates, use UNION ALL when duplicates are acceptable

You can measure 4 liters by following these steps:

• Fill the 5 liters container completely

• Pour the 5 liters into the 3 liters container, leaving 2 liters in the 5 liters container

• Empty the 3 liters container

• Pour the remaining 2 liters from the 5 liters container into the 3 liters container

• Fill the 5 liters container again

• Pour 1 liter from the 5 liters container into the 3 liters container, which now has 3 liters

• The 5 liters container now has 4 liters

Regular expression for 10-digit numeric characters starting with 1, 2, or 3.

• Use the pattern ^[1-3]\d{9}$ to match the criteria

• The ^ symbol denotes the start of the string

• The [1-3] specifies that the first digit must be 1, 2, or 3

• \d{9} matches exactly 9 numeric digits

• $ indicates the end of the string

Efficiently comparing large files in COBOL requires optimized I/O and data handling techniques.

• Use indexed files for faster access. Example: Use VSAM or DB2 for indexed data retrieval.

• Read files in chunks to minimize memory usage. Example: Process 1000 records at a time.

• Utilize SORT and MERGE utilities for preliminary sorting before comparison.

• Implement hashing techniques to quickly identify unique records.

• Consider using multi-threading if supported by the COBOL environment.

Data encapsulation is the concept of bundling data with the methods that operate on that data within a class.

• Data encapsulation restricts access to certain components of an object, protecting the data from external interference.

• It allows for better control over the data by hiding the implementation details and only exposing necessary information through methods.

• Encapsulation helps in achieving data abstraction, where the internal representation of an object is hidden from the...read more

Types of search include linear search, binary search, and hash table search. They are used in real life for finding information efficiently.

• Linear search: sequentially checks each element in a list until a match is found.

• Binary search: divides a sorted array in half to quickly find the target value.

• Hash table search: uses a hash function to map keys to values for fast retrieval.

• Real life example: Using linear search to find a specific book in a library.

• Real life example: Usin...read more

Varying parameters can be passed using arrays of strings in COBOL to stored procedures.

• Define an array in COBOL to hold the parameters

• Populate the array with the varying parameters

• Pass the array as a parameter to the stored procedure

• In the stored procedure, use the array to access the varying parameters

Software development life cycle (SDLC) is a process followed to develop software. Testing is done to ensure quality and functionality.

• SDLC is a process that includes planning, designing, coding, testing, and maintenance.

• Testing is done to identify and fix defects, ensure functionality, and improve quality.

• Types of testing include unit testing, integration testing, system testing, and acceptance testing.

• Testing can be manual or automated, and should be done throughout the SDLC...read more

The algorithm for the upcoming semester project involves developing an application.

• Identify the requirements and objectives of the project

• Design the application architecture and user interface

• Implement the necessary algorithms and data structures

• Test and debug the application

• Optimize the performance and efficiency of the code

• Document the project for future reference

A join in SQL is used to combine rows from two or more tables based on a related column between them.

• Types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

• INNER JOIN returns rows when there is at least one match in both tables.

• LEFT JOIN returns all rows from the left table and the matched rows from the right table.

• RIGHT JOIN returns all rows from the right table and the matched rows from the left table.

• FULL JOIN returns rows when there is a match in one of t...read more

Create a simple UI to fetch and display data using GET requests in a web application.

• Use Fetch API to make GET requests: `fetch('https://api.example.com/data')`.

• Handle the response using `.then()` to convert it to JSON: `.then(response => response.json())`.

• Use state management (like React's useState) to store fetched data.

• Map through the data to create card components: `data.map(item => <Card key={item.id} {...item} />)`.

• Style the cards using CSS for better presentation.

Incode refers to the code that is embedded within a program. Deadlock recovery is the process of resolving deadlocks in a system. Hierarchical file structure is a way of organizing files in a hierarchical manner.

• Incode refers to the code that is written within a program.

• Deadlock recovery involves detecting and resolving deadlocks in a system.

• Hierarchical file structure organizes files in a tree-like structure with parent and child relationships.

• Example of incode: Inline funct...read more