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Enterprise Java Notes • Interview Questions • Code Examples • Cheat Sheets

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Core Java

OOPs Concepts

Encapsulation, Inheritance, Polymorphism, Abstraction, SOLID Principles and Interview Questions.

Open

Collections Framework

List, Set, Map, Queue, Internal Working, Interview Questions and Examples.

Open

Stream API

Filter, Map, FlatMap, Reduce, Collectors, Grouping, Sorting and Examples.

Open

Multithreading

Threads, Synchronization, Executor Framework, Callable, Future and Locks.

Open

Exception Handling

Checked Exceptions, Runtime Exceptions, Custom Exceptions and Best Practices.

Open

JDBC

Connection, Statement, PreparedStatement, Transactions and Batch Processing.

Open

Spring Ecosystem

Spring Core

IOC, Dependency Injection, Bean Lifecycle and Configuration.

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Spring Boot

Auto Configuration, REST APIs, Validation, JPA, Security and Enterprise Development.

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Microservices

API Gateway, Eureka, Config Server, Feign Client, Resilience4j and Distributed Systems.

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Advanced Topics

Design Patterns

Singleton, Factory, Builder, Strategy, Observer and Enterprise Patterns.

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Java Interview Questions

Frequently Asked Interview Questions with Answers and Examples.

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Coming Soon...

More Java concepts, tutorials and enterprise examples will be added regularly.

Soon

Cheatsheets

01. Core Java

OOPs, Data Types, Operators, Loops, Arrays, Strings, and Fundamentals.

Open

02. Collections Framework

List, Set, Map, Queue, Internal Working, and Interview Questions.

Open

03. Multithreading & Exception Handling

Threads, Synchronization, Executor Framework, Locks, Callable & Future.

Open

04. Java 8 Features

Lambda, Stream API, Functional Interfaces, Optional, Date & Time API.

Open

05. JVM & Memory Management

JVM Architecture, Heap, Stack, Garbage Collection, Class Loader.

Open

06. Spring Core

IOC, Dependency Injection, Bean Lifecycle, Configuration, AOP.

Open

07. Spring Boot

Auto Configuration, REST APIs, Validation, Profiles, Actuator.

Open

08. Spring MVC & REST API

Controllers, Request Mapping, DTOs, Validation, REST Best Practices.

Open

09. Spring Data JPA & Hibernate

Entity Mapping, Repositories, JPQL, Relationships, Performance.

Open

10. Spring Security + JWT

Authentication, Authorization, JWT, Filters, Role-Based Security.

Open

11. Microservices

Service Discovery, API Gateway, Config Server, Feign, Resilience4j.

Open