Java
If you like applying Java, every challenge here gives you a chance to practice it on a real industry brief.
- CodeAdvancedNew
Build a Streaming Pipeline for Real-Time Fraud Detection
Receive 30 days of anonymized card-transaction events (around 240M events total), the team's existing batch features (cardholder behavior summaries), and a pre-trained fraud-sco…
- Stream Processing
- Kafka
- Flink
Big Data and Data-Intensive Systems - AnalysisAdvancedNew
Mutation Testing on a Critical Pricing Service
Run PIT against the pricing service to get a baseline mutation score per class. Identify the 5 classes with the largest gap between line coverage and mutation score (these are t…
- Mutation Testing
- Java
- Junit
Software Testing and Quality Assurance - CodeIntermediateNew
Build a Plugin-Based Notification Framework With Observer + Factory
Implement, in Java 21: an EventBus that supports typed subscriptions, a NotificationChannel interface with concrete subtypes (Push, Email, InApp, SMS), an AbstractChannelFactory…
- Java
- Design Patterns
- Oo Design
Object-Oriented Programming and Design - CodeIntermediateNew
Refactor a Tangled Java Pricing Engine With Design Patterns
Start from a provided Java 21 codebase with the legacy PricingEngine class, 38 example fixtures (input cart, expected price), and one failing test demonstrating a bug from last …
- Java
- Design Patterns
- Refactoring
Object-Oriented Programming and Design Practice your coursework on real scenarios.
Every challenge is shaped from real industry context — not generic exercises. The work mirrors what your degree prepares you for.
Why Ewance
- CodeIntermediateNew
Apply SOLID to a Java Reporting Service for a Renewable Energy Startup
Receive the legacy ReportService, 4 sample report templates (Daily Output, Monthly P&L, Annual Availability, Curtailment), and 22 fixtures (input dataset, expected report). Refa…
- Java
- Solid Principles
- Refactoring
Object-Oriented Programming and Design - CodeIntermediateNew
Design a Race-Free Cache for a Read-Heavy Service
Implement a thread-safe LRU-bounded cache in Java (or Go — your choice, defend it) with: read-write lock or copy-on-write semantics, get-or-load pattern with single-flight to de…
- Concurrent Data Structures
- Race Conditions
- Single Flight
Concurrent and Parallel Programming - CodeIntermediateNew
Containerize a Legacy Java Monolith and Deploy to ECS
Receive the Java 8 monolith source (around 320k lines), the current Tomcat + Apache HTTPD config, and 30 days of production traffic logs. Containerize the application (multi-sta…
- Containerization
- Docker
- Aws
Cloud Computing - CodeIntermediateNew
Design a Domain Model for a Library Loan System (Java)
Implement, in Java 21, an Item type hierarchy (Book, AudioBook, Periodical, EquipmentLoan — each with sub-type-specific rules), Member with eligibility logic, Loan as an aggrega…
- Java
- Oo Design
- Domain Modeling
Object-Oriented Programming and Design - Browse challenges
Explore role
Product Manager
Ship product that solves real user problems. Combine user research, prototyping, and stakeholder alignment to turn ambiguous briefs into measurable wins — the role at the centre of modern software teams.
- CodeIntermediateNew
Diagnose and Fix a Deadlock in a Multi-Threaded Payments Service
Receive the service source (Java 21 + Spring Boot, around 30,000 lines), 4 thread dumps from production deadlocks, and a load harness that reproduces the bug roughly 1 in 50 run…
- Deadlock Analysis
- Locks And Monitors
- Java
Concurrent and Parallel Programming
How it works
From brief to credential, in six steps.
Step 01
Browse challenges aligned to your studies.
Step 02
Accept the one that fits your goals.
Step 03
Work through it with AI Copilot guidance.
Step 04
Submit for structured evaluation.
Step 05
Earn a verified credential.
Step 06
Add it to LinkedIn with one click.
Industry teams behind a decade of practitioner briefs
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Sponsor a challenge and meet candidates through actual work.
Industry teams can shape briefs around the skills they hire for, then evaluate students on rubric-scored deliverables — not resumes.