Java API Consistency Validator

Overview

This skill validates API consistency between two versions of Java libraries by comparing signatures, behavior, and exceptions. It identifies breaking changes, incompatible modifications, and provides detailed reports to guide safe API migration or upgrade.

Quick Start

# Compare two versions of a Java library
python scripts/validate.py /path/to/old_version /path/to/new_version

# Specify output file
python scripts/validate.py old_lib/ new_lib/ --output report.json

What Gets Validated

1. Method Signatures - Parameters, return types, modifiers
2. Class Definitions - Methods, inheritance, interfaces
3. Interface Changes - Method additions, removals
4. Parameter Changes - Added, removed, or modified parameters
5. Return Type Changes - Modified return types
6. Exception Declarations - throws clauses
7. Removed APIs - Deleted classes, interfaces, or methods

Validation Report

The tool generates a JSON report with:

• Breaking Changes: API removals, incompatible modifications
• Warnings: Type changes, signature modifications
• Info: New additions, non-breaking changes
• Summary: Total issues by severity

Example report:

{
  "summary": {
    "breaking_changes": 3,
    "warnings": 5,
    "info": 2
  },
  "breaking_changes": [
    {
      "type": "method_removed",
      "class": "UserService",
      "method": "getUser",
      "severity": "breaking",
      "message": "Method 'UserService.getUser' was removed"
    }
  ]
}

Usage

python scripts/validate.py <old_version_path> <new_version_path> [--output <report.json>]

The validator exits with code 1 if breaking changes are found, 0 otherwise.

Tips

• Run validation before upgrading dependencies
• Review breaking changes carefully
• Check warnings for potential issues
• Use in CI/CD pipelines to catch API changes
• Compare against semantic versioning expectations
• Validate before releasing new library versions