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Indecent Exposure

We teach our kids to cover up, and we should teach our code to do the same. "Indecent Exposure" occurs when a class or method reveals more than it should. It involves making methods, fields, or classes public when they really should be private or protected.

Every time you make something public, you are signing a contract with the rest of the world (or at least the rest of your codebase) that says, "I promise to support this method/field." If you expose your internals, other developers will use them, and then you can't change them without breaking their code.

Signs of the Smell​

  • Fields are public (unless they are constants).
  • Helper methods used only internally are marked public.
  • Classes meant for internal package use are exposed to the whole project.

Reasons of the Smell​

Laziness: "I'll just make it public so I can test it easily" or "I need to call it from this one other place, making it public is fastest." Lack of Understanding: Not fully grasping encapsulation or the specific visibility modifiers of the language.

Refactoring Recipe​

  • Encapsulate Field
  • Reduce Visibility (Change access modifiers)

Encapsulate Field​

Never make fields public. Always provide getters and setters (and only if necessary).

Before:

class Student {
    public int score; // Anyone can change this to -100
}

After:

class Student {
    private int score;

    public int getScore() {
        return score;
    }
    
    // Maybe we don't even want a setter!
    public void addPoints(int points) {
        if (points > 0) this.score += points;
    }
}

Reduce Visibility​

If a method is only used inside the class, make it private. If it's only used in the package, make it package-private (default in Java).

Before:

public class OrderProcessor {
    // This is an internal helper, why is it public?
    public void validateInternalState() { ... }
    
    public void process() {
        validateInternalState();
        // ...
    }
}

After:

public class OrderProcessor {
    private void validateInternalState() { ... }
    
    public void process() {
        validateInternalState();
        // ...
    }
}

References​