List of topics you need to cover if you're preparing for Java Interviews based on current Job market:
1. Core Java Fundamentals (Refer to already posted topics)
2. Advanced Java
- Design Patterns
- Multithreading
- Java Memory Model
- Performance Optimization
- Reflection & Dynamic Proxies
3. Spring Framework
- Spring core concepts
- Spring boot
- Spring Data JPA
- Spring Security
- Spring cloud
- Spring webflux
4. Hibernate
5. Testing (JUnit, Mockito, Integration, Functional, Performance Testing)
6. Build Tools (Maven / Gradle)
7. Logging
8. RDBMS, NoSQL DBs
9. WebSecurity Concepts
10. REST API concepts
11. CI/CD (Jenkins, GitHub Actions)
12. Containerization (Docker, Kubernetes)
13. Version Control (GitHub)
14. Monitoring (Grafana, ELK Stack etc)
15. Cloud (AWS, Azure, GCP (Very rare) )
16. Spring boot microservices
16. Messaging systems
17. Caching Strategies
18. System Design
19. Data Structures
20. Algorithms
21. Agile Methodologies
22. Behavioral questions
1. Core Java Fundamentals (Refer to already posted topics)
2. Advanced Java
- Design Patterns
- Multithreading
- Java Memory Model
- Performance Optimization
- Reflection & Dynamic Proxies
3. Spring Framework
- Spring core concepts
- Spring boot
- Spring Data JPA
- Spring Security
- Spring cloud
- Spring webflux
4. Hibernate
5. Testing (JUnit, Mockito, Integration, Functional, Performance Testing)
6. Build Tools (Maven / Gradle)
7. Logging
8. RDBMS, NoSQL DBs
9. WebSecurity Concepts
10. REST API concepts
11. CI/CD (Jenkins, GitHub Actions)
12. Containerization (Docker, Kubernetes)
13. Version Control (GitHub)
14. Monitoring (Grafana, ELK Stack etc)
15. Cloud (AWS, Azure, GCP (Very rare) )
16. Spring boot microservices
16. Messaging systems
17. Caching Strategies
18. System Design
19. Data Structures
20. Algorithms
21. Agile Methodologies
22. Behavioral questions
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🏆 – Java Developer
Stage 1 – Java Basics (Syntax, Data Types, Variables)
Stage 2 – Object-Oriented Programming (OOP)
Stage 3 – Exception Handling
Stage 4 – Java Collections Framework
Stage 5 – File I/O
Stage 6 – Multithreading and Concurrency
Stage 7 – Java Streams and Lambda Expressions
Stage 8 – JDBC
Stage 9 – Servlets and JSP
Stage 10 – Spring Framework Basics
Stage 11 – Spring Boot
Stage 12 – RESTful APIs with Spring
Stage 13 – Testing
Stage 14 – Deployment
Stage 15 – Build projects
Stage 1 – Java Basics (Syntax, Data Types, Variables)
Stage 2 – Object-Oriented Programming (OOP)
Stage 3 – Exception Handling
Stage 4 – Java Collections Framework
Stage 5 – File I/O
Stage 6 – Multithreading and Concurrency
Stage 7 – Java Streams and Lambda Expressions
Stage 8 – JDBC
Stage 9 – Servlets and JSP
Stage 10 – Spring Framework Basics
Stage 11 – Spring Boot
Stage 12 – RESTful APIs with Spring
Stage 13 – Testing
Stage 14 – Deployment
Stage 15 – Build projects
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Typical java interview questions sorted by experience
Junior
* Name some of the characteristics of OO programming languages
* What are the access modifiers you know? What does each one do?
* What is the difference between overriding and overloading a method in Java?
* What’s the difference between an Interface and an abstract class?
* Can an Interface extend another Interface?
* What does the static word mean in Java?
* Can a static method be overridden in Java?
* What is Polymorphism? What about Inheritance?
* Can a constructor be inherited?
* Do objects get passed by reference or value in Java? Elaborate on that.
* What’s the difference between using == and .equals on a string?
* What is the hashCode() and equals() used for?
* What does the interface Serializable do? What about Parcelable in Android?
* Why are Array and ArrayList different? When would you use each?
* What’s the difference between an Integer and int?
* What is a ThreadPool? Is it better than using several “simple” threads?
* What the difference between local, instance and class variables?
Mid
* What is reflection?
* What is dependency injection? Can you name a few libraries? (Have you used any?)
* What are strong, soft and weak references in Java?
* What does the keyword synchronized mean?
* Can you have “memory leaks” on Java?
* Do you need to set references to null on Java/Android?
* What does it means to say that a String is immutable?
* What are transient and volatile modifiers?
* What is the finalize() method?
* How does the try{} finally{} works?
* What is the difference between instantiation and initialisation of an object?
* When is a static block run?
* Why are Generics are used in Java?
* Can you mention the design patterns you know? Which of those do you normally use?
* Can you mention some types of testing you know?
Senior
* How does Integer.parseInt() works?
* Do you know what is the “double check locking” problem?
* Do you know the difference between StringBuffer and StringBuilder?
* How is a StringBuilder implemented to avoid the immutable string allocation problem?
* What does Class.forName method do?
* What is Autoboxing and Unboxing?
* What’s the difference between an Enumeration and an Iterator?
* What is the difference between fail-fast and fail safe in Java?
* What is PermGen in Java?
* What is a Java priority queue?
* *s performance influenced by using the same number in different types: Int, Double and Float?
* What is the Java Heap?
* What is daemon thread?
* Can a dead thread be restarted?
Source: medium.
Junior
* Name some of the characteristics of OO programming languages
* What are the access modifiers you know? What does each one do?
* What is the difference between overriding and overloading a method in Java?
* What’s the difference between an Interface and an abstract class?
* Can an Interface extend another Interface?
* What does the static word mean in Java?
* Can a static method be overridden in Java?
* What is Polymorphism? What about Inheritance?
* Can a constructor be inherited?
* Do objects get passed by reference or value in Java? Elaborate on that.
* What’s the difference between using == and .equals on a string?
* What is the hashCode() and equals() used for?
* What does the interface Serializable do? What about Parcelable in Android?
* Why are Array and ArrayList different? When would you use each?
* What’s the difference between an Integer and int?
* What is a ThreadPool? Is it better than using several “simple” threads?
* What the difference between local, instance and class variables?
Mid
* What is reflection?
* What is dependency injection? Can you name a few libraries? (Have you used any?)
* What are strong, soft and weak references in Java?
* What does the keyword synchronized mean?
* Can you have “memory leaks” on Java?
* Do you need to set references to null on Java/Android?
* What does it means to say that a String is immutable?
* What are transient and volatile modifiers?
* What is the finalize() method?
* How does the try{} finally{} works?
* What is the difference between instantiation and initialisation of an object?
* When is a static block run?
* Why are Generics are used in Java?
* Can you mention the design patterns you know? Which of those do you normally use?
* Can you mention some types of testing you know?
Senior
* How does Integer.parseInt() works?
* Do you know what is the “double check locking” problem?
* Do you know the difference between StringBuffer and StringBuilder?
* How is a StringBuilder implemented to avoid the immutable string allocation problem?
* What does Class.forName method do?
* What is Autoboxing and Unboxing?
* What’s the difference between an Enumeration and an Iterator?
* What is the difference between fail-fast and fail safe in Java?
* What is PermGen in Java?
* What is a Java priority queue?
* *s performance influenced by using the same number in different types: Int, Double and Float?
* What is the Java Heap?
* What is daemon thread?
* Can a dead thread be restarted?
Source: medium.
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Java project ideas to help you practice your skills
1. ToDo List Application: Create a command-line or GUI-based application that allows users to create, manage, and organize their tasks.
2. Calculator: Build a simple calculator application that can perform basic arithmetic operations like addition, subtraction, multiplication, and division.
3. Library Management System: Design a system for managing library resources, including books, patrons, and borrowing records.
4. Chat Application: Develop a chat application that enables users to communicate in real-time, either as a desktop app or through a web interface.
5. Weather App: Create an app that fetches weather data from an API and displays current weather conditions for a given location.
6. Student Gradebook: Build a program to store and calculate student grades. You can add features like grade averages and report generation.
7. Expense Tracker: Create an application for tracking expenses and generating reports, helping users manage their finances.
8. Simple Game (e.g., Tic-Tac-Toe): Implement a classic game like Tic-Tac-Toe to learn about game logic and user interaction.
9. Blog or Content Management System (CMS): Build a simple blog or CMS where users can create, edit, and publish articles.
10. E-commerce Shopping Cart: Create a basic online shopping cart system with product listings, a shopping cart, and checkout functionality.
11. File Manager: Develop a file manager application that allows users to organize and manage files and directories on their computer.
12. Inventory System: Design an inventory management system for tracking products, quantities, and orders for a small business.
13. Music Player: Create a basic music player with features like play, pause, skip, and a library of songs.
14. Password Manager: Build a secure application for storing and managing passwords and other sensitive information.
15. Chess or Sudoku Solver: Implement a chess game or a Sudoku puzzle solver to delve into complex algorithms and logic.
16. Note-taking App: Develop a note-taking application with features like creating, editing, and organizing notes.
17. Expense Sharing App: Build an app for groups to track shared expenses and split bills among friends or roommates.
18. Task Scheduler: Create a program that allows users to schedule and manage tasks, reminders, and appointments.
19. Mini Social Media Platform: Create a simplified social media platform with features like user profiles, posting, and commenting.
20. Quiz or Flashcard Application: Design an app for creating and taking quizzes or using flashcards to study various topics.
Choose a project that aligns with your interests and skill level. As you work on these projects, you'll gain valuable experience and improve your Java programming skills.
1. ToDo List Application: Create a command-line or GUI-based application that allows users to create, manage, and organize their tasks.
2. Calculator: Build a simple calculator application that can perform basic arithmetic operations like addition, subtraction, multiplication, and division.
3. Library Management System: Design a system for managing library resources, including books, patrons, and borrowing records.
4. Chat Application: Develop a chat application that enables users to communicate in real-time, either as a desktop app or through a web interface.
5. Weather App: Create an app that fetches weather data from an API and displays current weather conditions for a given location.
6. Student Gradebook: Build a program to store and calculate student grades. You can add features like grade averages and report generation.
7. Expense Tracker: Create an application for tracking expenses and generating reports, helping users manage their finances.
8. Simple Game (e.g., Tic-Tac-Toe): Implement a classic game like Tic-Tac-Toe to learn about game logic and user interaction.
9. Blog or Content Management System (CMS): Build a simple blog or CMS where users can create, edit, and publish articles.
10. E-commerce Shopping Cart: Create a basic online shopping cart system with product listings, a shopping cart, and checkout functionality.
11. File Manager: Develop a file manager application that allows users to organize and manage files and directories on their computer.
12. Inventory System: Design an inventory management system for tracking products, quantities, and orders for a small business.
13. Music Player: Create a basic music player with features like play, pause, skip, and a library of songs.
14. Password Manager: Build a secure application for storing and managing passwords and other sensitive information.
15. Chess or Sudoku Solver: Implement a chess game or a Sudoku puzzle solver to delve into complex algorithms and logic.
16. Note-taking App: Develop a note-taking application with features like creating, editing, and organizing notes.
17. Expense Sharing App: Build an app for groups to track shared expenses and split bills among friends or roommates.
18. Task Scheduler: Create a program that allows users to schedule and manage tasks, reminders, and appointments.
19. Mini Social Media Platform: Create a simplified social media platform with features like user profiles, posting, and commenting.
20. Quiz or Flashcard Application: Design an app for creating and taking quizzes or using flashcards to study various topics.
Choose a project that aligns with your interests and skill level. As you work on these projects, you'll gain valuable experience and improve your Java programming skills.
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