Decomposition

Algorithmic decomposition

• The process of breaking down a problem into well-defined steps
• Object-oriented decomposition breaks a large system down into progressively smaller classes
• Cognitive skills used in decomposition: abstraction, decision making, inference, analysis, synthesis, etc.
• Design paradigms: top-down and bottom-up programming

Top-down vs. Bottom-up

Top-down development: start at implementing the most general modules

The bottom-up development: start at implementing the modules that provide specific functionality and then integrate them into more general modules

In practice, there is no pure bottom-up or pure top-down design. A problem solver attempts several approaches on the path to the final solution (Charitsis et al., 2022)

Decomposition steps

1. abstract the problem from its description
2. generate subproblems
3. transform subproblems into subsolutions
4. recompose the subsolutions into a working program
5. evaluate and iterate

Refactoring

Goal: identify subsolutions, recompose the subsolutions into a working program

Problem: game of Tic-Tac-Toe

Download the TicTacToe.java file and refactor it into multiple classes with appropriate methods. This assignment focuses on breaking a large problem down into smaller subproblems and properly incorporate encapsulation, inheritance, and polymorphism.

Write JUnit tests

Now that you have classes and methods, write JUnit tests to test your game functionality.