Design Patterns and Best Practices in Java

Open/closed principle

This principle is as follows:

"Modules, classes, and functions should be open for extension but closed for modifications."

Applying this principle will help us to develop complex and robust software. We must imagine the software we develop is building a complex structure. Once we finish a part of it, we should not modify it any more but build on top of it.

When developing software, it's the same. Once we have developed and tested a module, if we want to change it, we must test not only the functionality we are changing but the entire functionality it's responsible for. That involves a lot of additional resources, which might not have been estimated from the beginning, and also can bring additional risks. Changes in one ...