Java Programming
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Everything you need to learn Java Programming

Daily Java tutorials, coding challenges, OOP concepts, DSA in Java & more!
Perfect for beginners, CS students & job seekers.

Downloadable PDFs, cheat sheets, interview prep & projects

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"Java Project Workshop ☕️"

Master Java programming through hands-on projects! From basic calculators to advanced applications like ATM systems and face detection, build real-world solutions while strengthening your Java skills. Perfect for beginners and intermediate developers looking to expand their portfolio.
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⌨️ Useful CSS grid cheat sheet

You’ve seen this many times. But practice makes perfect, right?
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Real word Java coding standards and best practices.pdf
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Real word Java coding standards and best practices 🚀

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Goldman Sachs
Day 30/100
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Java, Spring Boot, Microservices, and Angular.pdf
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Java, Spring Boot, Microservices, and Angular Interview Preparation Guide 🔥

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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
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Java vs Javascript
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Don't Confuse Yourself While Learning Java!

*𝗕𝗮𝘀𝗶𝗰𝘀 𝗼𝗳 𝗝𝗮𝘃𝗮:*
• Java Syntax & Structure
• Data Types & Variables
• Operators
• Control Flow:
- if-else, switch
- for, while, do-while loops
- break & continue
- try-catch-finally
• Methods
• Packages & Imports

*𝗢𝗯𝗷𝗲𝗰𝘁-𝗢𝗿𝗶𝗲𝗻𝘁𝗲𝗱 𝗣𝗿𝗼𝗴𝗿𝗮𝗺𝗺𝗶𝗻𝗴 𝗶𝗻 𝗝𝗮𝘃𝗮:*
• Classes & Objects
• Inheritance
• Polymorphism
• Encapsulation
• Abstraction
• Constructors & Overloading

*𝗝𝗮𝘃𝗮 𝗖𝗼𝗹𝗹𝗲𝗰𝘁𝗶𝗼𝗻𝘀 𝗙𝗿𝗮𝗺𝗲𝘄𝗼𝗿𝗸:*
• List, Set, Map, Queue
• ArrayList, HashSet, HashMap, LinkedList
• Iterators & Loops
• Sorting & Filtering

*𝗘𝘅𝗰𝗲𝗽𝘁𝗶𝗼𝗻 𝗛𝗮𝗻𝗱𝗹𝗶𝗻𝗴:*
• try-catch
• throw, throws
• Custom Exceptions
• Exception Hierarchy

*𝗙𝗶𝗹𝗲 𝗛𝗮𝗻𝗱𝗹𝗶𝗻𝗴 𝗶𝗻 𝗝𝗮𝘃𝗮:*
• Reading/Writing Files
• FileReader & BufferedReader
• FileWriter & BufferedWriter
• Working with JSON & CSV

*𝗝𝗮𝘃𝗮 𝗟𝗶𝗯𝗿𝗮𝗿𝗶𝗲𝘀 & 𝗧𝗼𝗼𝗹𝘀:*
• Apache Commons
• Jackson / Gson for JSON
• JUnit for Testing
• Maven / Gradle

*𝗗𝗮𝘁𝗮 𝗦𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗲𝘀 𝗶𝗻 𝗝𝗮𝘃𝗮:*
• Arrays
• Strings
• Lists
• Stacks & Queues
• HashMaps
• Trees & Graphs (Basic)

*𝗠𝘂𝗹𝘁𝗶𝘁𝗵𝗿𝗲𝗮𝗱𝗶𝗻𝗴 𝗮𝗻𝗱 𝗖𝗼𝗻𝗰𝘂𝗿𝗿𝗲𝗻𝗰𝘆:*
• Threads & Runnable
• Synchronization
• ExecutorService
• Concurrency Utilities

*𝗔𝗱𝘃𝗮𝗻𝗰𝗲𝗱 𝗧𝗼𝗽𝗶𝗰𝘀:*
• Lambda Expressions
• Streams API
• Functional Interfaces
• Java 8+ Features
• Generics
• Reflection API

💬 Tap ❤️ for more!
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Java_OOP-Cheat_Sheet.pdf
255 KB
Java OOP Concepts Cheat Sheet 📘

Master Java’s Object-Oriented pillars:

🔹 Class & Object
🔹 Inheritance
🔹 Polymorphism
🔹 Abstraction
🔹 Encapsulation

React ❤️ if you love clean Java code!
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Var Vs let Vs const
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Java Developer Interview
It'll gonna be super helpful for YOU

𝗧𝗼𝗽𝗶𝗰 𝟭: 𝗣𝗿𝗼𝗷𝗲𝗰𝘁 𝗳𝗹𝗼𝘄 𝗮𝗻𝗱 𝗮𝗿𝗰𝗵𝗶𝘁𝗲𝗰𝘁𝘂𝗿𝗲
- Please tell me about your project and its architecture, Challenges faced?
- What was your role in the project? Tech Stack of project? why this stack?
- Problem you solved during the project? How collaboration within the team?
- What lessons did you learn from working on this project?
- If you could go back, what would you do differently in this project?

𝗧𝗼𝗽𝗶𝗰 𝟮: 𝗖𝗼𝗿𝗲 𝗝𝗮𝘃𝗮
- String Concepts/Hashcode- Equal Methods
- Immutability
- OOPS concepts
- Serialization
- Collection Framework
- Exception Handling
- Multithreading
- Java Memory Model
- Garbage collection

𝗧𝗼𝗽𝗶𝗰 𝟯: 𝗝𝗮𝘃𝗮-𝟴/𝗝𝗮𝘃𝗮-𝟭𝟭/𝗝𝗮𝘃𝗮𝟭𝟳
- Java 8 features
- Default/Static methods
- Lambda expression
- Functional interfaces
- Optional API
- Stream API
- Pattern matching
- Text block
- Modules

𝗧𝗼𝗽𝗶𝗰 𝟰: 𝗦𝗽𝗿𝗶𝗻𝗴 𝗙𝗿𝗮𝗺𝗲𝘄𝗼𝗿𝗸, 𝗦𝗽𝗿𝗶𝗻𝗴-𝗕𝗼𝗼𝘁, 𝗠𝗶𝗰𝗿𝗼𝘀𝗲𝗿𝘃𝗶𝗰𝗲, 𝗮𝗻𝗱 𝗥𝗲𝘀𝘁 𝗔𝗣𝗜
- Dependency Injection/IOC, Spring MVC
- Configuration, Annotations, CRUD
- Bean, Scopes, Profiles, Bean lifecycle
- App context/Bean context
- AOP, Exception Handler, Control Advice
- Security (JWT, Oauth)
- Actuators
- WebFlux and Mono Framework
- HTTP methods
- JPA
- Microservice concepts
- Spring Cloud

𝗧𝗼𝗽𝗶𝗰 𝟱: 𝗛𝗶𝗯𝗲𝗿𝗻𝗮𝘁𝗲/𝗦𝗽𝗿𝗶𝗻𝗴-𝗱𝗮𝘁𝗮 𝗝𝗽𝗮/𝗗𝗮𝘁𝗮𝗯𝗮𝘀𝗲 (𝗦𝗤𝗟 𝗼𝗿 𝗡𝗼𝗦𝗤𝗟)
- JPA Repositories
- Relationship with Entities
- SQL queries on Employee department
- Queries, Highest Nth salary queries
- Relational and No-Relational DB concepts
- CRUD operations in DB
- Joins, indexing, procs, function

𝗧𝗼𝗽𝗶𝗰 𝟲: 𝗖𝗼𝗱𝗶𝗻𝗴
- DSA Related Questions
- Sorting and searching using Java API.
- Stream API coding Questions

𝗧𝗼𝗽𝗶𝗰 𝟳: 𝗗𝗲𝘃𝗼𝗽𝘀 𝗾𝘂𝗲𝘀𝘁𝗶𝗼𝗻𝘀 𝗼𝗻 𝗱𝗲𝗽𝗹𝗼𝘆𝗺𝗲𝗻𝘁 𝗧𝗼𝗼𝗹𝘀
- These types of topics are mostly asked by managers or leads who are heavily working on it, That's why they may grill you on DevOps/deployment-related tools, You should have an understanding of common tools like Jenkins, Kubernetes, Kafka, Cloud, and all.

𝗧𝗼𝗽𝗶𝗰𝘀 𝟴: 𝗕𝗲𝘀𝘁 𝗽𝗿𝗮𝗰𝘁𝗶𝗰𝗲
- The interviewer always wanted to ask about some design patterns, it may be Normal design patterns like singleton, factory, or observer patterns to know that you can use these in coding.

Make sure to scroll through the above messages 💝 definitely you will get the more interesting things 🤠

All the best 👍👍
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Join our WhatsApp channel for Java Projects
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Core Java.pdf
718.8 KB
Core Java Notes
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𝟴 𝗦𝗸𝗶𝗹𝗹𝘀 𝗧𝗼 𝗠𝗮𝘀𝘁𝗲𝗿 𝗕𝗲𝗳𝗼𝗿𝗲 𝗘𝗻𝘁𝗲𝗿𝗶𝗻𝗴 𝗜𝗻𝘁𝗼 𝟮𝟬𝟮𝟲😍

- Python Programming
- Data Analytics
- ChatGPT
- Data Visualization With Power BI
- Generative AI
- Data Science 
- Tableau
- Java & SQL 
 
𝗦𝘁𝗮𝗿𝘁 𝗡𝗼𝘄👇:-

https://pdlink.in/4m3FwTX

Learn Online | Get Certified With Pro Courses🎓
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Polymorphism in Java

📍 Polymorphism allows a single interface to be used for different types of actions.
📍 It is of two types:

Method Overloading (Compile-time Polymorphism)

Method Overriding (Runtime Polymorphism)


Method Overloading (Same method name, different parameters)

class MathOperations {
int add(int a, int b) {
return a + b;
}

double add(double a, double b) {
return a + b;
}
}

Method Overriding (Same method in parent and child class)

class Animal {
void makeSound() {
System.out.println("Animal makes a sound");
}
}

class Dog extends Animal {
void makeSound() {
System.out.println("Dog barks");
}
}

🔗 More Java Resources: https://whatsapp.com/channel/0029VamdH5mHAdNMHMSBwg1s
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Day 31/100
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As a Java developer,

Please learn:

1. Core Java Mastery
- OOP principles (SOLID, DRY, KISS)
- Generics, Lambda expressions, Functional interfaces
- Java Streams API (map/reduce, collectors)
- Java Collections framework
- Java Reflection API
- Exception handling

2. Multithreading & Concurrency
- Thread synchronization, Executors, Locks
- Fork/Join framework
- Understanding of race conditions, deadlocks, and thread pools
- Concurrency utilities (java.util.concurrent)

3. Design Patterns & Architecture
- Common design patterns (Singleton, Factory, Builder)
- Architectural patterns (MVC, - Microservices, Event-Driven Architecture)
- Dependency Injection (DI), Inversion of Control (IoC)

4. Java Memory Management
- Garbage Collection (G1, CMS, ZGC)
- JVM heap and stack management
- Profiling tools (JProfiler, VisualVM)
- Analyzing memory leaks, thread dumps, and heap dumps

5. Classloaders and Reflection
- Custom class loaders
- Dynamic class loading
- Reflection for runtime behavior manipulation

6. Spring Framework & Spring Boot
- Spring Core (Dependency Injection, AOP)
- Spring Boot (Auto-configuration, Microservices support)
- Spring Security (OAuth2, JWT)
- Spring Data (JPA, Hibernate integration)
- Spring Cloud (Netflix OSS, Circuit Breakers)

7. Microservices Architecture
- Service discovery (Eureka, Consul)
- Load balancing, distributed tracing, and circuit breaking
- API Gateway (Zuul, NGINX)
- Asynchronous communication with Kafka, RabbitMQ

8. RESTful Web Services
- REST principles, building APIs
- JSON/XML handling
- API versioning, OpenAPI/Swagger documentation

9. Java I/O and NIO
- Blocking vs non-blocking I/O (NIO)
- Asynchronous I/O, channels, selectors
- File handling, serialization and deserialization

10. Reactive Programming
- Project Reactor, RxJava
- Event-driven architecture, backpressure
- Reactive streams, non-blocking IO

11. JPA/Hibernate
- ORM principles, entity relationships
- Lazy vs eager loading
- Caching strategies, query optimization

12. Database Optimization
- SQL optimization, indexing, and transactions
- NoSQL databases (MongoDB, Cassandra)
- ACID principles, CAP theorem

13. Distributed Systems
- Consistency, availability, partitioning (CAP)
- Event sourcing, CQRS (Command Query Responsibility Segregation)
- Distributed caching (Redis, Hazelcast)
- Tools: Apache ZooKeeper, Consul, etcd

14. Testing & TDD/BDD
- Unit testing (JUnit, Mockito)
- Integration and functional testing
- Behavior-driven development (Cucumber)

15. CI/CD & DevOps
- Continuous integration (Jenkins, CircleCI)
- Containerization with Docker
- Orchestration with Kubernetes
- Source control (Git), versioning, branching strategies

16. Performance Tuning & Optimization
- JVM tuning, garbage collection optimization
-Tools for profiling and monitoring (Prometheus, Grafana)
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Java Basics every beginner should learn to build a strong foundation:

1. Hello World & Setup

Install JDK and an IDE (like IntelliJ or Eclipse)

Write your first program: public class HelloWorld

2. Data Types & Variables

Primitive types: int, double, char, boolean

Non-primitive types: String, Arrays, Objects

Type casting (implicit & explicit)

3. Operators

Arithmetic: + - * / %

Comparison: == != > < >= <=

Logical: && || !

4. Control Flow

If, else if, else

Switch-case

Loops: for, while, do-while

break and continue

5. Functions (Methods)

Syntax: public static returnType methodName(params)

Method overloading

Return types & parameter passing

6. Object-Oriented Programming (OOP)

Classes & Objects

this keyword

Constructors (default & parameterized)

7. OOP Concepts

Encapsulation (private variables + getters/setters)

Inheritance (extends keyword)

Polymorphism (method overriding)

Abstraction (abstract classes & interfaces)

8. Arrays & ArrayList

Declaring and iterating arrays

ArrayList methods: add, remove, get, size

Multidimensional arrays

9. Exception Handling

Try-catch-finally blocks

throw and throws

Custom exceptions

10. Basic Input/Output

Scanner class for user input

System.out.println() for output

Free Java Resources: https://whatsapp.com/channel/0029VamdH5mHAdNMHMSBwg1s

ENJOY LEARNING 👍👍
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