UML, U of what?
Updated: Nov 19, 2019
What's UML? Go ahead look it up, I'll wait. No, not UMass Lowell it's Unified Modeling Language. The current UML Standard, 2.0, has been around since 2005. With 14 different diagram standards UML allows individuals to work at a much higher level of abstraction. I'm familiar with UML from creating ERD diagrams while doing RDBMS work. As a developer it allows me to write pseudo-code quicker, cleaner and platform independent.
From a developers stand point, let's take a look at an example and break it down. I found the example below at
I really enjoy the content at Medium.com, the articles, reviews and tutorials are all helpful and well written.
This is a typical Class diagram representing 4 classes: Animal, Duck, Fish, Zebra. Notice how each of the four blocks are structured the same. Let's focus on the Animal block. In the upper box notice that Animal is written with a bold font. This indicates that Animal is a concrete class. Abstract classes would be italicized. The next box down is where you define attributes. Public attributes are denoted using a + while private attributes use a -. Looking at our example this would translate into JAVA like this:
public Int age;
public String gender;
The lower box is for methods or functions. The same convention is used for dentoing public or private methods. In the Animal class the example would translate to:
Note the example is missing the return types for methods. The convention is to follow the paranthesis with a colon and list the return type. In our example isMammal would be
+isMammal () : boolean
Relationships between the classes are denoted using lines, arrows and diamonds. In our example the solid line with the white filled arrow indicates inheritance. The article/tutorial above has a great png showing the different relationship lines. The number of online resources for information related to drawing UML diagrams is staggering. For more information and to take a deeper dive into UML go to the source and check it out https://www.uml.org