Persistent Systems Java Technology Lead Interview Questions, Process, and Tips

Q1. Explain architecture of your project
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Q2. Some questions on Java, Spring Boot and sql
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Q1. Project flow and some behavioural questions
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Q2. Project contribution of yours
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Developed a web application for tracking employee attendance and performance
• Implemented user authentication and authorization using Spring Security

• Utilized Hibernate for database interaction and data persistence

• Designed and developed RESTful APIs for frontend integration

• Used AngularJS for frontend development to create interactive user interfaces
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Q1. Basic formalities before offer release
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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. Comparable and comparator
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Q2. Singleton class
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Q3. Springboot questions were asked
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Q4. Java class loader
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Q5. Java 8 coding questions
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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. What is Executer Service?
Ans. 
ExecutorService is an interface in Java that provides a way to manage and control the execution of threads in a multithreaded environment.
• It is part of the java.util.concurrent package.

• It provides methods to submit tasks for execution, manage thread pools, and control the execution of tasks.

• It allows for the execution of tasks asynchronously and provides features like scheduling, cancellation, and monitoring of tasks.

• E...read more
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Q2. What is the use of JPA?
Ans. 
JPA is a Java specification for mapping Java objects to relational databases.
• JPA stands for Java Persistence API

• It provides a way to map Java objects to database tables and vice versa

• JPA simplifies the development of data access layer in Java applications

• It supports object-relational mapping (ORM) and allows developers to work with entities, relationships, and queries in a more object-oriented way
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Q3. Explain about PreparedStatement
Ans. 
PreparedStatement is used in Java to execute parameterized SQL queries to prevent SQL injection attacks.
• PreparedStatement is a subinterface of Statement in Java.

• It is used to execute parameterized SQL queries.

• It helps prevent SQL injection attacks by automatically escaping special characters.

• Example: PreparedStatement pstmt = connection.prepareStatement("SELECT * FROM users WHERE username = ?");
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Q4. Program to find the missing numbers from Array
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Program to find missing numbers from Array
• Iterate through the array and store each number in a HashSet

• Then iterate from 1 to the length of the array and check if each number exists in the HashSet

• If a number is not found in the HashSet, it is a missing number
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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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Q1. Comparable vs Comparator
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Comparable is an interface used for natural ordering, while Comparator is used for custom ordering in Java.
• Comparable interface is used to define the natural ordering of objects. It is implemented by the class whose objects are to be sorted.

• Comparator interface is used to define custom ordering of objects. It is implemented by a separate class that compares objects based on specific criteria.

• Example: Sorting a list of ...read more
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Q2. Difference between List and Set

Ans. 

List allows duplicate elements and maintains insertion order, while Set does not allow duplicates and does not maintain order.

• List can contain duplicate elements, Set cannot

• List maintains insertion order, Set does not guarantee order

• List is implemented by classes like ArrayList, LinkedList, Set is implemented by classes like HashSet, TreeSet

• Example: List list = new ArrayList<>(); Set set = new HashSet<>();

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