Learn Java 21 from Hello World to object-oriented programs: types, strings, loops, methods, arrays and lists, classes, inheritance, interfaces, exceptions, recursion, collections, files and a complete bank-account project.
Lesson 1 is free to try. The other 15 lessons in Java are for schools on RudimentaryLabs.
How Java programs are compiled and run, and the values, text, decisions and loops every program is made of.
Breaking programs into small methods, and storing many values in arrays and ArrayLists.
Designing your own types with classes, then reusing and extending them with inheritance, polymorphism and interfaces.
Handling things that go wrong, and solving problems with methods that call themselves.
Maps, sets and generics, reading input and files, and a complete bank-account system built step by step.