interfaces-and-abstraction 5 encapsulation 4 design-patterns 3 inheritance 3 polymorphism 3 solid 3 unit-testing 3 reflection-and-annotation 2 working-with-abstraction 2 generics 2 functional-programming 1 implementing-linked-list 1 iterators-and-comparators 1 multidimensional-arrays 1 oop 1 queues 1 sets-and-dictionaries-advanced 1 stacks 1 streams-files-and-directories 1 exceptions-and-error-handling 1 repository-pattern 1 mvc-pattern 1 mvc-architecture 1 dependency-injection 1 abstraction 1 typescript 1 oop-in-typescript 1 classes-and-inheritance 1 access-modifiers 1 test-driven-development 1