10+ Campus shoes Interview Questions and Answers

Example of using Java 8 features and stream api to get distinct elements in a list.

• Use the distinct() method of the Stream interface to get distinct elements in a list.

• The distinct() method returns a stream consisting of the distinct elements of the original stream.

• Example: List list = Arrays.asList("apple", "banana", "apple", "orange"); list.stream().distinct().forEach(System.out::println);

• Output: apple banana orange

Index in DB is a data structure that improves the speed of data retrieval operations on a database table.

• Index in DB is used to quickly locate and access the rows in a table based on the values in specific columns.

• It helps in optimizing query performance by reducing the number of rows that need to be scanned.

• Examples of indexes include primary keys, unique keys, and composite indexes.

• Creating indexes on frequently queried columns can significantly improve database performance...read more

Design patterns used in Microservices

• Service Registry Pattern

• API Gateway Pattern

• Circuit Breaker Pattern

• Event Sourcing Pattern

• Saga Pattern

Answering the question about Rest Api using Spring Boot

• Spring Boot is a popular framework for building RESTful APIs

• It provides easy configuration and setup for REST endpoints

• Annotations like @RestController and @RequestMapping are used to define endpoints

• Spring Boot also includes features like security, caching, and database integration

• Example: @GetMapping("/users") public List getUsers() { return userService.getAllUsers(); }

Microservices communicate with each other through APIs and messaging protocols.

• Microservices communicate via RESTful APIs, using HTTP requests and responses.

• Message brokers like Kafka or RabbitMQ are used for asynchronous communication between microservices.

• Service discovery tools like Eureka or Consul help microservices locate and communicate with each other.

• Microservices can also communicate through gRPC, a high-performance RPC framework.

An example of a REST API coding

• Define endpoints and HTTP methods

• Implement CRUD operations

• Use JSON for data exchange

• Handle errors and exceptions

• Secure API with authentication and authorization

MySQL join types and their differences

• INNER JOIN returns only matching rows from both tables

• LEFT JOIN returns all rows from left table and matching rows from right table

• RIGHT JOIN returns all rows from right table and matching rows from left table

• FULL OUTER JOIN returns all rows from both tables

• CROSS JOIN returns all possible combinations of rows from both tables

James Gosling is the developer of Java.

• James Gosling developed Java while working at Sun Microsystems in the early 1990s.

• Java was originally called Oak and was designed for use in consumer electronics.

• Java's popularity grew with the rise of the internet and its ability to run on multiple platforms.

• Oracle Corporation acquired Sun Microsystems in 2010 and now owns Java.

We are using Log4j2 for logging in the current project.

• Log4j2 is a popular logging framework in Java.

• It provides support for logging at different levels like DEBUG, INFO, WARN, ERROR, etc.

• Configuration can be done through XML, JSON, or properties file.

• Example: org.apache.logging.log4j log4j-api 2.14.1

There are many packages in Java.

• Java has a vast collection of packages for various purposes.

• Some commonly used packages are java.lang, java.util, java.io, java.net, etc.

• Packages provide a way to organize and reuse code.

• Developers can also create their own packages for their projects.

Java is a popular programming language known for its platform independence and object-oriented approach. New features include modules, var keyword, and more.

• Java is a high-level, class-based, object-oriented programming language.

• New features in Java include modules for better code organization, the var keyword for type inference, and enhancements in the Java Platform Module System (JPMS).

• Java 14 introduced switch expressions, records, and text blocks as new features.

• Java 15 a...read more

Java is a high-level, object-oriented programming language used to develop applications for various platforms.

• Java is platform-independent and can run on any device with a Java Virtual Machine (JVM)

• It is known for its security features and is commonly used for developing web and mobile applications

• Java is also used for developing enterprise-level applications and software tools

• Examples of popular Java-based frameworks include Spring, Hibernate, and Struts

An operator is a symbol or keyword used to perform operations on one or more operands in a programming language.

• Operators are used to perform mathematical, logical, and comparison operations.

• Examples of operators in Java include +, -, *, /, %, ==, !=, <, >, &&, ||, etc.

• Unary operators operate on a single operand, while binary operators operate on two operands.

• Ternary operator ?: is a conditional operator that takes three operands.

• Bitwise operators are used to perform operatio...read more

Java has around 100 packages that provide various functionalities.

• Java packages are used to organize related classes and interfaces.

• Some commonly used packages are java.lang, java.util, java.io, java.net, etc.

• Packages can be imported using the import keyword.

• Packages can also be created by the user to organize their own classes and interfaces.

Exceptions are unexpected events that occur during the execution of a program, disrupting the normal flow of the program.

• Exceptions are objects that represent an abnormal condition or error in a program.

• They can be caught and handled using try-catch blocks.

• Unchecked exceptions do not need to be declared in a method's throws clause, while checked exceptions do.

• Examples include NullPointerException, ArrayIndexOutOfBoundsException, and IOException.