Grappus Java Developer Interview Questions and Answers

A standard online test conducted through one of the testing platforms.

Q1. Java 8 features
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Q2. Rest API
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Q3. Java 8 coding problem
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Q4. Collections
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Q1. It was based on my previous project
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Q1. What are primitive and non primitive data types
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Primitive data types are basic data types provided by the programming language, while non-primitive data types are created by the programmer.
• Primitive data types include int, float, double, char, boolean, etc.

• Non-primitive data types include arrays, classes, interfaces, etc.

• Primitive data types store actual values, while non-primitive data types store references to objects.
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Q2. What are access modifiers and non access modifiers
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Access modifiers control the visibility of classes, methods, and variables. Non-access modifiers provide additional functionality.
• Access modifiers: public, private, protected, default

• Non-access modifiers: static, final, abstract, synchronized

• Example: public class MyClass { private int myVar; }
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Q3. What are all Java 8 features and explain the one which we have used in our project
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Java 8 features include lambda expressions, functional interfaces, streams, and more.
• Lambda expressions allow concise syntax for defining anonymous functions.

• Functional interfaces can have only one abstract method and are used for lambda expressions.

• Streams provide a way to process collections of objects in a functional style.

• Optional class helps to avoid NullPointerException by wrapping a value that may be null.
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Q4. CICD tools which we have used explain in high level
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CICD tools automate the process of building, testing, and deploying code changes.
• Popular CICD tools include Jenkins, GitLab CI/CD, CircleCI, and Travis CI

• These tools help in automating the software development lifecycle

• They enable continuous integration, continuous delivery, and continuous deployment

• CICD tools help in improving code quality, reducing manual errors, and increasing development speed
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Q5. What is containerization
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Containerization is a lightweight, portable, and self-sufficient way to package and run applications.
• Containerization involves encapsulating an application and its dependencies into a container image.

• Containers are isolated from each other and share the host OS kernel.

• Popular containerization platforms include Docker and Kubernetes.

• Containerization allows for easy deployment and scaling of applications.
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Q6. What is indexing in sql
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Indexing in SQL is a technique used to improve the performance of queries by creating a data structure that allows for faster retrieval of data.
• Indexes are created on columns in a database table to speed up the retrieval of rows that match a certain condition in a query.

• They work similar to the index in a book, allowing the database to quickly locate the rows that satisfy the query.

• Indexes can be created using a single...read more
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Q7. Programming question on stream like finding the longest string in a given list of string
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Q1. Tell me about your project
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Developed a web-based inventory management system for a retail company.
• Used Java, Spring Boot, and MySQL for backend development.

• Implemented user authentication and authorization using Spring Security.

• Designed a responsive front-end using HTML, CSS, and JavaScript.

• Integrated barcode scanning functionality for efficient inventory tracking.
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Q2. Class vs object
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A class is a blueprint or template for creating objects, while an object is an instance of a class.
• A class defines the properties and behaviors of objects, while an object is a specific instance of a class.

• Classes can be used to create multiple objects with similar characteristics.

• Objects have state (attributes) and behavior (methods) defined by the class.

• Example: Class 'Car' defines properties like 'color' and 'model'...read more
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Q1. Salary expectation
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Q2. Date to join?
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Q1. Chvvvv vvbbbbb isush shjshs jdudjdj
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Q1. Diff between abstract class and interface
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Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.
• Abstract class can have constructor, fields, and methods, while interface cannot have any of these.

• A class can extend only one abstract class, but can implement multiple interfaces.

• Abstract classes are used to define a common behavior among subclasses, while interfaces are used to define a contract for classes...read more
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Q2. Explain about handler methods
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Handler methods in Java are methods that are responsible for handling incoming requests and generating responses.
• Handler methods are typically defined in classes annotated with @Controller or @RestController.

• These methods are mapped to specific URLs using @RequestMapping or other mapping annotations.

• Handler methods can have parameters such as HttpServletRequest, HttpServletResponse, or model attributes.

• The return value...read more
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Q1. Prime number program
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A program to check if a given number is prime or not.
• Create a function to check if a number is prime by iterating from 2 to the square root of the number.

• If the number is divisible by any number other than 1 and itself, it is not prime.

• Handle edge cases like 0, 1, and negative numbers separately.
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Q2. 3rd highest salary employee
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To find the 3rd highest salary employee, we can use a SQL query with the 'LIMIT' and 'OFFSET' keywords.
• Use a SQL query to select distinct salaries in descending order

• Use 'LIMIT 1 OFFSET 2' to get the 3rd highest salary

• Join this result with the employee table to get the employee details
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Q1. They asked some core Java Concepts,String,Java 8,SpringBoot Architecture,Stream API code
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Aptitude questions and some questions from PostgreSQL.

Q1. Java fundamental questions?
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Q2. Collection Framework.
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Q3. 2-3 easy to medium Coding Questions.
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Q4. Questions from Object oriented programming in Java?
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Q5. Implementation of HashMap , LinkedList, HashSet, Heap?
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HashMap, LinkedList, HashSet, and Heap are data structures commonly used in Java for storing and organizing data.
• HashMap: key-value pairs, uses hashing to store and retrieve elements efficiently (e.g. HashMap)

• LinkedList: linear data structure, elements are stored in nodes with pointers to the next node (e.g. LinkedList)

• HashSet: collection of unique elements, uses hashing to ensure uniqueness (e.g. Hash...read more
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