How do you represent protected in UML?

Representing Protected Members in UML Class Diagrams: Making Sense of the Hash

Ever felt like UML diagrams are a secret language? They can be, especially when you’re trying to figure out the nuances of object-oriented design. One of those nuances is understanding how to represent “protected” members. So, let’s break it down in plain English.

UML, or Unified Modeling Language, is basically a visual blueprint for software systems. Think of class diagrams as the architectural plans for your code, showing you all the classes, their attributes (data), methods (actions), and how they all relate. Now, when designing these classes, you’ve got to decide who gets to see what – that’s where visibility comes in.

We’ve got a few options here:

• Public (+): This is like shouting from the rooftops. Everyone can see and use these members.
• Private (-): Super secretive! Only the class itself can access these members. Nobody else gets a peek.
• Package (~): Think of this as “internal” access. Only classes within the same package can see these members. Honestly, it’s not used as much as the others.
• Protected (#): Ah, the star of our show! This is like saying, “Okay, family only.” The class itself and its subclasses (the classes that inherit from it) can access these members. Outsiders? Nope.

So, how do you actually show a protected member in a UML diagram? Simple: slap a “#” symbol right in front of its name. This little hash tells everyone that this attribute or operation is protected. You’ll find this notation inside the class rectangle, which is divided into three parts: name at the top, attributes in the middle, and operations at the bottom.

Let’s say we have an Animal class, and it has a protected attribute called breed and a protected method called getBreed. Here’s how it would look in UML:

asciidoc