ecs business solutions Senior Software Engineer Interview Questions and Answers

OOP is a programming paradigm based on the concept of objects, which can contain data in the form of fields and code in the form of procedures.

• OOP focuses on creating objects that interact with each other to solve complex problems

• Objects have attributes (data) and methods (functions) that operate on the data

• Encapsulation, inheritance, and polymorphism are key principles of OOP

• Example: A car object with attributes like ...read more

Singleton design pattern ensures a class has only one instance and provides a global point of access to it.

• Singleton pattern restricts the instantiation of a class to one object.

• It provides a way to access the unique instance of the class globally.

• Commonly used in scenarios where only one instance of a class is needed, such as database connections or logging.

• Implementation can be achieved using static variables, lazy i...read more

Java Collection Framework is a set of classes and interfaces that provide various data structures and algorithms to store and manipulate collections of objects.

• Includes interfaces like List, Set, Queue, and classes like ArrayList, LinkedList, HashSet, PriorityQueue

• Provides implementations for common data structures like lists, sets, maps, queues, stacks

• Offers algorithms for searching, sorting, and manipulating collecti...read more

ArrayList is implemented as a resizable array, while LinkedList is implemented as a doubly linked list.

• ArrayList provides fast random access and slower insertion/deletion, while LinkedList provides fast insertion/deletion and slower random access.

• ArrayList uses less memory overhead compared to LinkedList.

• Example: ArrayList is more suitable for scenarios where random access is frequent, while LinkedList is more suitable...read more

HashMap is a data structure that stores key-value pairs and uses hashing to quickly retrieve values based on keys.

• HashMap internally uses an array of linked lists to store key-value pairs.

• When a key-value pair is added, the key is hashed to determine the index in the array where it will be stored.

• If multiple keys hash to the same index, a linked list is used to handle collisions.

• To retrieve a value, the key is hashed a...read more

Different ways to create strings in Java include using string literals, the new keyword, and the String class constructor.

• String literals: String str = "Hello World";

• Using new keyword: String str = new String("Hello World");

• String class constructor: char[] charArray = {'H', 'e', 'l', 'l', 'o'}; String str = new String(charArray);

StringBuffer is synchronized and thread-safe, while StringBuilder is not synchronized and faster.

• StringBuffer is synchronized, meaning it is thread-safe and multiple threads can access it at the same time without any issues.

• StringBuilder is not synchronized, making it faster but not thread-safe. It is recommended for single-threaded operations.

• Use StringBuffer when working with multiple threads and synchronization is r...read more

Developing a web application for inventory management system

• Using React for front-end development

• Implementing RESTful APIs with Node.js for back-end

• Utilizing PostgreSQL for database management

I have faced challenges with integrating a new third-party API and resolving performance issues.

• Integrating a new third-party API required extensive research and testing to ensure compatibility with existing systems.

• Resolving performance issues involved analyzing code, identifying bottlenecks, and implementing optimizations.

• Collaborating with team members to troubleshoot and address issues in a timely manner.

• Prioritizi...read more