I've made a visual representation of Object Calisthenics by Jeff Bay. There's also a nice write-up about it by Willian Durand.

Visual Object Calisthenics

Here's the 9 rules:

  1. Only one level of indentation per method
  2. Don't use the else keyword
  3. Wrap all primitives and Strings
  4. First class collections
  5. One dot per line
  6. Don't abbreviate
  7. Keep all entities small
  8. No classes with more than two instance variables
  9. No getters/setters/properties

I also made a pdf for easy printing.