[x] - Variables, Primitive Types
[x] - Control Flow
[x] - Control Flow / Loops
[x] - OOP - Classes, Constructors, Inheritance
[x] - OOP - Composition, Encapsulation, Polymorphism
[x] - Arrays, Lists, Autoboxing, Unboxing
[x] - Interfaces
[x] - Abstract
[x] - Inner Class
[x] - Control Flow
[x] - Generics
[x] - Static and Final
[x] - Collections (List)
[x] - Collections (Maps)
[x] - Collections (Sets and HashSet)
[] - Concurrency
[] - Lambda Expressions
[] - Regular Expressions