Core Java Chapter 0 : Fundamentals Data Types and Variables - https://www.baeldung.com/java-primitives Access Modifiers - https://www.baeldung.com/java-access-modifiers If-Else https://www.baeldung.com/java-control-structures https://www.baeldung.com/java-using-not-in-if-conditions Switch Case - https://www.baeldung.com/java-switch Loops - https://www.baeldung.com/java-loops OOP Concepts - https://www.baeldung.com/java-oop