World 0 / 0.1
Java 25 for Kotlin Developers
Build the translation table you will use for the rest of the course.
javatutorial.imdmp.com
Palabas API Course
Learn modern Java backend development by building one real Spring Boot API from scratch. No toy CRUD, no frontend detour, no fake production claims.
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Built for JVM engineers
A course site over a real repo, not a sandbox fantasy.
The site teaches. The Palabas repo proves. Every quest names a concrete task, the command that verifies it, and the artifact that should exist afterward.
MVP progress is local to your browser. Hosted graders, GitHub OAuth, and AI hints wait until at least Phase 1 is fully teachable.
First public slice
Published lessons
0 complete locallyWorld 1 / 1.1
Generate the Spring Skeleton
Create the smallest Spring Boot app that can carry the rest of the curriculum.
World 1 / 1.3
Constructor Injection and the Wiring Test
Wire controller to service to repository without hiding dependencies.
World 1 / 1.6
ADR-001: Layers and Versioning Stance
Commit the API versioning decision before future endpoints multiply.
World 1 / Boss
Phase 1 Boss Fight: Prove the API Skeleton
Finish Phase 1 with tests, curl output, ADR-001, and a tag.
World 2A / 2A.0
Preview: Schema First
See why the database model comes before JPA entities.
World 2A / 2A.1
Cinema and Screen Schema
Create the first Flyway migration for cinemas and screens before any JPA entity exists.
World 2A / 2A.2
Movie and Showtime Schema
Model showtimes as booking facts with stored occupancy windows.
World 2A / 2A.3
Postgres Exclusion Constraint
Enforce no overlapping showtimes per screen with a GiST exclusion constraint.
World 2A / 2A.4
Indexes and EXPLAIN
Add indexes for known reads and capture the planner story without forcing a fake win.
World 2A / Boss
Phase 2A Boss Fight: Let SQL Prove It
Finish SQL-first by proving constraints, notes, time handling, ERD, seed data, and EXPLAIN artifacts exist together.
Java Delta
A committed kata file with notes on records, Optional, streams, sealed switch, and virtual threads.
Spring Skeleton
A wiring test, curl transcript, ADR-001, and a phase-1-done tag.
SQL First
Constraints, EXPLAIN transcripts, schema notes, and time notes.