Copperpod Digital Interview Questions and Answers

Annotations used in Spring Boot applications

• 1. @RestController - Marks a class as a controller that handles HTTP requests

• 2. @RequestMapping - Maps HTTP requests to handler methods

• 3. @Autowired - Injects dependencies into a bean

• 4. @Service - Marks a class as a service component

• 5. @Repository - Marks a class as a repository component

• 6. @Component - Marks a class as a generic Spring component

• 7. @Configuration - Indicates that a class provides bean definitions

• 8. @Value - Injects ...read more

Abstract classes and methods in Java provide a way to define common behavior that can be inherited by subclasses.

• An abstract class is a class that cannot be instantiated and is meant to be extended by other classes.

• An abstract method is a method that is declared without an implementation in an abstract class.

• Subclasses of an abstract class must provide an implementation for all abstract methods.

• Abstract classes can have both abstract and non-abstract methods.

• Abstract classes ...read more

Object-oriented programming concepts that help in designing and implementing software systems.

• Encapsulation: bundling data and methods together

• Inheritance: creating new classes from existing ones

• Polymorphism: using a single interface to represent different types

• Abstraction: hiding complex implementation details

• Encapsulation: grouping related data and methods together

• Association: relationship between classes

• Composition: combining objects to create more complex ones

• Aggregation:...read more

DOM stands for Document Object Model in JavaScript, which represents the structure of a webpage as a tree of objects.

• DOM is a programming interface for web documents.

• It allows scripts to dynamically access and update the content, structure, and style of a webpage.

• DOM represents the HTML elements as objects, allowing manipulation through JavaScript.

• Example: document.getElementById('myElement') retrieves an element with the specified ID.

Find the second largest number in an array

• Sort the array in descending order

• Return the second element in the sorted array

A self join query is used to join a table to itself in a SQL query.

• Self join is used when a table needs to be joined with itself to compare rows within the same table.

• It requires aliasing the table with different names to distinguish between the two instances of the same table.

• Commonly used in hierarchical data structures or when comparing related rows in a table.

Group by query is used to group data based on a specific category.

• Use the GROUP BY clause in SQL to group data based on a specific column

• Aggregate functions like COUNT, SUM, AVG can be used with GROUP BY to perform calculations on grouped data

• Example: SELECT category, COUNT(*) FROM products GROUP BY category

Find the maximum value in an array of strings.

• Iterate through the array and compare each element to find the maximum value.

• Convert the strings to numbers if needed before comparison.

• Handle edge cases like empty array or non-numeric strings.