JavaBeginner
Learn Java
Codecademy's Learn Java course runs entirely in the browser, so you write and run real Java without installing a JDK first. By the end you can build simple object-oriented programs: classes, inheritance, interfaces, and basic data structures like arrays and ArrayLists. It's a solid pick if you're new to Java specifically, even with experience in another language, since the built-in editor catches syntax errors as you type. Skip it if you already know object-oriented basics elsewhere and just want Java syntax fast: the pacing is patient, not a quick reference. The free tier stops short of a certificate, and a few later exercises nudge toward Codecademy Pro.