I recently went through Just Enuf Java v2, a concise set of Java course notes written by Professor Jason Leigh at the University of Hawaiʻi at Mānoa — who was my professor there.
It covers the core fundamentals of Java in a clear, practical way — primitives, control structures, functions, object-oriented programming, arrays, inheritance, polymorphism, file handling, and exception handling. It’s written in a straightforward style that makes it easy to follow while learning.
I’m using it alongside IntelliJ IDEA and Java 26 as I continue building my programming foundation.