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Intermediate Java in 21 days

Streams, lambdas, Optional, Spring Boot basics, and multithreading for professional Java development.

  • Daily plan, 45-60 min a day
  • 7 lessons + 21 exercises
  • AI tutor included
duration21-day sprint
Topics7 total
Exercises21 total
levelIntermediate
  • No prior coding experience required
  • Practice tasks every day
  • Build impressive portfolio project

What you will learn

A powered by mentors Intermediate plan with structured subtopics, quizzes, and practice tasks.

01Core

Streams and lambda expressions

Process collections with the Stream API and functional lambdas.

02Core

Functional interfaces and method references

Use Function, Predicate, and Consumer interfaces with method references.

03Core

Optional and null safety

Eliminate NullPointerExceptions with Optional chaining and ifPresent.

04Core

Spring Boot basics

Build a REST API with Spring Boot, controllers, and service layers.

05Core

Unit testing with JUnit and Mockito

Write tests with JUnit 5 and mock dependencies with Mockito.

06Challenge

Multithreading and concurrency basics

Use threads, ExecutorService, and synchronized blocks safely.

07Challenge

Capstone: REST API with Spring Boot

Build and test a full REST API with Spring Boot and JUnit.

See the quiz + practice flow

Three answered questions and a filled code task so you know exactly what to expect.

Quiz preview

2/3 correct

1. How long is the Java plan?

Correct
21-day sprint
5-day sprint
7-day sprint
10-day sprint

2. What level is this Java plan?

Incorrect
Beginner
Intermediate
Advanced
Expert

3. Which of these appears in the Java outline?

Correct
Streams and lambda expressions
Java workflow playbook
Java best-practice checklist
Java case study

Code practice preview

Submitted

Format a lesson title

Build a helper that formats a lesson label with a padded index and title.

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