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Code Smells

Detecting God Classes: Signs Your File Does Too Much

A comprehensive guide to identifying and breaking apart God classes that hurt your codebase maintainability.

DiffScan Team•2026-02-01•6 min read

Detecting God Classes

A "God class" is a file that knows too much and does too much. It's an anti-pattern that makes code hard to understand, test, and maintain.

Signs of a God Class

  • High line count - Usually 1000+ lines
  • Many methods - 20+ public methods
  • Multiple responsibilities - Does logging, validation, business logic, and database access
  • High churn - Changed in many commits by many authors
  • Tangled dependencies - Imports half the codebase

    • Why God Classes Are Dangerous

  • **Hard to test** - Too many dependencies to mock
  • **Merge conflicts** - Multiple developers touching the same file
  • **Bug magnets** - Changes in one area break another
  • **Knowledge silos** - Only one person understands it

    • How to Refactor

    Step 1: Identify Responsibilities

    List everything the class does. Group related functionality.

    Step 2: Extract Classes

    Create new classes for each responsibility group.

    Step 3: Use Composition

    The original class can coordinate the new classes.

    Step 4: Add Tests

    Before and after refactoring, ensure behavior is preserved.

    Using DiffScan for Detection

    DiffScan automatically flags potential God classes based on:

    - File size (lines of code)

    - Churn score

    - Number of contributors

    - Import complexity

    Look for the "🏛️ God Class" badge in your analysis results.

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