Core Java Study Guide with Java Fundamentals to Java 25

A free study guide on Java with 20 lessons you can study step by step.

What you will learn

Part 1 · Language basics

• Variables, primitive types, and var
• Operators and expressions
• Control flow: if, and the classic switch
• Loops: for, while, and enhanced for-each
• Arrays and Strings
• Strings in depth: immutability, the pool and StringBuilder

Part 2 · Objects and classes

• Classes, objects, and constructors
• Stack, heap and references: what a variable really holds
• Encapsulation with access modifiers
• Inheritance and super
• Polymorphism: overriding vs overloading
• Interfaces, abstract classes, and default methods
• Value classes: equals, hashCode, toString and immutability

Part 3 · Collections and generics

• The Collections Framework hierarchy
• List, Set, and Map in practice
• Generics and type safety
• Iterators, for-each, and ConcurrentModificationException
• Comparable vs Comparator

Part 4 · Exceptions

• Exception handling: try, catch, finally, and try-with-resources
• Checked vs unchecked exceptions

All tutorials · Practice quizzes