/to-java-migration

name: to-java-migration
description: Migrate COBOL code to idiomatic Java, preserving business logic while following Java best practices. Use for COBOL modernization projects.
license: MIT
compatibility: Requires Java 11+, Maven or Gradle
triggers:
  - cobol to java
  - cobol migration
  - cobol modernization
  - migrate cobol

Migrate COBOL code to idiomatic Java, preserving all business logic.

Code Style Requirements

Write idiomatic Java, NOT literal COBOL translations:

• Use Java conventions: camelCase names, standard collections (List, Map)
• Use Java standard library instead of rolling your own
• No god classes — split into cohesive, single-responsibility classes
• No TODO comments or stub implementations — fully implement everything

Robustness Requirements

• Validate inputs at method entry (null checks, range validation)
• Use try-catch for all I/O and external operations
• Use try-with-resources for files, streams, connections
• Handle errors gracefully with meaningful messages

Configuration Requirements

• No hardcoded file paths or credentials — use environment variables
• No magic numbers — use named constants
• Make limits and timeouts configurable

Documentation Requirements

• Add COBOL references: `// COBOL equivalent: BNK1CRA.cbl 145-167`
• Document assumptions made during conversion
• Add Javadoc to public methods

Testing Requirements

If test fixtures exist (see `cobol-build-setup` skill):

• Create a JUnit test class for each migrated program
• Load inputs from fixtures, assert output matches expected (golden) output
• All tests must pass before migration is complete

References

• See [references/cobol-to-java-example.md](references/cobol-to-java-example.md) for a complete transformation example
• See [references/datatype-mappings.md](references/datatype-mappings.md) for COBOL→Java type mappings

Done When

✓ Code compiles without errors ✓ All JUnit tests pass (Java output matches COBOL golden output) ✓ No TODO or stub implementations remain ✓ COBOL references documented in comments