Impact Guru Interview Questions and Answers

Classes needed to create a GET REST API

• Controller class to handle the request

• Service class to perform business logic

• Repository class to interact with database

• Model class to define data structure

• RequestMapping annotation to map the URL

An interface is a blueprint of a class. Default method is a method in an interface with a default implementation.

• An interface defines a set of methods that a class must implement

• Default method provides a default implementation for a method in an interface

• Default methods were introduced in Java 8

• Default methods can be overridden by implementing classes

HashMap is a data structure that stores key-value pairs. List is a collection of ordered elements.

• HashMap allows fast retrieval of values based on keys.

• List maintains the order of elements and allows duplicates.

• HashMap uses hashing to store and retrieve elements.

• List uses indexing to access elements.

• HashMap is not thread-safe while List is thread-safe.

• Example: HashMap map = new HashMap<>(); map.put("apple", 1);

• Example: List list = new ArrayList<>(); list.add("apple"); list.ad...read more

The class used to connect with the Database depends on the programming language and framework being used.

• In Java, the class used is usually DriverManager or DataSource.

• In Python, the class used is usually psycopg2 or mysql-connector.

• In PHP, the class used is usually PDO or mysqli.

• The specific class used may also depend on the type of database being used, such as MySQL, PostgreSQL, or MongoDB.

Creating Threads in Java

• Extending the Thread class and overriding the run() method

• Implementing the Runnable interface and passing it to a Thread constructor

• Using Executor framework to create and manage threads

• Using Callable and Future interfaces to create threads that return values

An interface is used to define a contract between two components in a system.

• An interface defines a set of methods that a class must implement.

• Interfaces are used to achieve abstraction and loose coupling.

• Interfaces are used to create reusable code.

• Interfaces are used to enable polymorphism.

• Interfaces are used in many programming languages, including Java, C#, and TypeScript.

MVC Lifecycle is the sequence of events that occur in the Model-View-Controller architectural pattern.

• MVC stands for Model-View-Controller.

• The lifecycle starts with a user request.

• The controller receives the request and processes it.

• The controller updates the model with the necessary data.

• The view is then updated with the updated model data.

• The updated view is sent back to the user as a response.

HashMap is a non-synchronized implementation of Map interface while HashTree is a synchronized implementation of Map interface.

• HashMap is faster than HashTree as it is non-synchronized.

• HashTree is thread-safe while HashMap is not.

• HashMap allows one null key and multiple null values while HashTree does not allow null keys or values.

• HashTree maintains the order of elements while HashMap does not.

• HashMap is generally used in single-threaded applications while HashTree is used in...read more