Expleo Group Java Developer Interview Questions, Process, and Tips

HashMap is a data structure in Java that stores key-value pairs and allows for fast retrieval of values based on keys.

• HashMap is part of the Java Collections framework.

• It implements the Map interface and uses hashing to store elements.

• Example: HashMap map = new HashMap<>(); map.put("key", 1); int value = map.get("key");

Internal implementation of set is typically based on hash table or balanced tree data structures.

• Sets are typically implemented using hash tables for faster access and retrieval of elements.

• Some sets, like TreeSet in Java, are implemented using balanced trees to maintain elements in sorted order.

• Internal implementation may vary based on the specific set implementation in a programming language.

Spring MVC is a framework for building web applications in Java. It follows the Model-View-Controller architectural pattern.

• Spring MVC separates the application into three main components: Model, View, and Controller.

• The Model represents the data and business logic of the application.

• The View is responsible for rendering the user interface.

• The Controller handles user requests, processes them, and interacts with the Mod...read more

Object-oriented programming (OOP) is a programming paradigm that uses objects to represent and manipulate data.

• OOP is based on the concept of classes and objects.

• It provides encapsulation, inheritance, and polymorphism.

• Encapsulation hides the internal details of an object and provides a public interface.

• Inheritance allows classes to inherit properties and methods from other classes.

• Polymorphism allows objects of differ...read more

The @Controller annotation is used to create a controller class in Spring MVC, while @RestController is used to create a RESTful web service.

• The @Controller annotation is used for traditional web applications that return views.

• The @RestController annotation is used for creating RESTful web services that return JSON or XML responses.

• The @RestController annotation is a combination of @Controller and @ResponseBody annotat...read more

To handle load in production server, we can use techniques like load balancing, caching, optimizing database queries, and scaling horizontally.

• Implement load balancing to distribute the incoming traffic across multiple servers.

• Use caching to store frequently accessed data and reduce the load on the server.

• Optimize database queries by indexing, using query optimization techniques, and avoiding unnecessary queries.

• Scale ...read more