A software artifact should be open for extension but closed for modification. OCP is the architectural goal that drives Clean Architecture: protect high-level policy from changes in low-level details by controlling the direction of dependencies.
Comprehensive OCP Java SE 21 (1Z0-830) exam cheat-sheet: output tracing strategy, compile vs runtime errors, Java 21 new features, mnemonics, top traps across all 14 chapters, functional interface cheatsheet, stream operations, collections comparison, and a final checklist.
A structured Docusaurus study guide covering all 14 chapters of the OCP Oracle Certified Professional Java SE 21 Developer exam (1Z0-830), with beginner explanations, senior deep-dives, exam tips, and Spring framework context.