Apache Kafka Complete Tutorial: From Beginner to Production
Apache Kafka is one of the most important technologies used in modern distributed systems, event-driven architectures, and microservices.
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public class Singleton {
private static final Singleton INSTANCE = new Singleton();
private Singleton() {}
public static Singleton getInstance() { return INSTANCE; }
public static void main(String[] args) {
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Core Java through Spring Boot, JPA, security, microservices, Kafka, and cloud-native ops â day by day.
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system design interviews
MAANG-style system design: estimation, databases, caching, distributed systems, and end-to-end design problems.
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Core Java
320
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180
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250
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210
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95
JVM Internals
140
Spring Boot
275
Microservices
160
Kafka
85
Hibernate / JPA
130
Design Patterns
110
Java 8
165
System Design
90
SQL & Database
200
Spring Security
75
AWS Basics
113
RESTful API
39
Git & GitHub
50
Docker
50
Spring Data JPA
50
Hibernate
50
quick java revision
Concept of the day
Jul 22, 2026 ¡ 5 cards
Coding practice
Hands-on problems asked in real interviews
The exact kind of coding rounds you'll face â solved, explained, and ready to practise.
easy
Java 8
Group employees by department (Streams)
Use Java 8 Streams and Collectors to group a list of employees by department name.
Solve
easy
Exception Handling
Custom InsufficientBalanceException
Model a bank withdraw that throws a checked custom exception when the balance is too low.
Solve
medium
Collection Framework
First non-repeating character
Find the first character that appears exactly once using LinkedHashMap to preserve order.
Solve
easy
SQL
Second highest salary (SQL)
Write a SQL query that returns the second highest distinct salary from the Employee table.
Solve
medium
Multithreading
Print odd & even with two threads
Coordinate two threads so numbers 1âŚN print in order: odd thread then even thread alternating.
Solve
medium
Design Patterns
Thread-safe Singleton
Implement a Singleton that is lazy and safe under concurrent first access.
Solve
The exact system
A method for cracking Java interviews
You know Java â but interviews test how you think under pressure. Here's the structure that closes that gap.
Structured roadmap
A step-by-step plan so you never feel lost or waste time on the wrong resources.
Real interview questions
Questions pulled from actual company rounds â FAANG to top Indian product firms.
Quick revision sheets
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Practical examples
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Latest content
Fresh interview prep
New question banks and guides â topic, scope, and how many questions at a glance.
Spring Boot Pagination with Spring Data JPA: A Complete End-to-End Guide
When building REST APIs, returning all records from a database table is rarely a good idea.
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Why Constructor Injection is Better Than Field Injection in Spring Boot?
Constructor Injection and Field Injection are two common ways to inject dependencies in Spring Boot.
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AWS basic interview questions
Practice 50+ interview questions with model answers â open any accordion to rehearse.
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