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Self-paced course

Learn Java

Learn Java from the ground up: syntax, object-oriented design, the Collections framework and modern Java 8+ features like lambdas, streams and Optional.

Teach yourself Java at your own pace — each lesson ends with exercises and interview questions so you can check your understanding before moving on.

Start with Introduction to Java →See the roadmap
Lessons
8
Total time
2.3h
Your progress
0%

Lessons

  1. 01

    Introduction to Java

    What Java is, how the JVM runs your code, and writing your first program.

  2. 02

    Variables, Types and Control Flow

    Store data in typed variables and make decisions with if, switch and loops.

  3. 03

    Classes and Objects

    Model real things with classes, constructors, encapsulation and records.

  4. 04

    Inheritance, Interfaces and Polymorphism

    Reuse and extend behaviour with inheritance, and program to interfaces for flexible code.

  5. 05

    The Collections Framework

    List, Set and Map — how they differ, how they perform, and how to choose.

  6. 06

    Lambdas and Functional Interfaces

    Pass behaviour as data with lambda expressions and method references.

  7. 07

    Java Streams

    Process collections declaratively with filter, map, reduce and collect.

  8. 08

    Optional

    Represent "maybe a value" explicitly and stop writing null checks everywhere.

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Java articles

Java

Java Streams in Practice: 10 Patterns You'll Use Every Day

The stream recipes that show up again and again in real backend code — grouping, lookups, deduplication, pagination and the mistakes to avoid.

2 min read · 24 Sept 2026Read

Java

How HashMap Works Internally in Java

Buckets, hashing, collisions, treeification and resizing — the HashMap internals every Java interview asks about, explained simply.

3 min read · 18 Sept 2026Read