This tutorial explains how a Java HashMap works internally and explores the challenges of implementing it, including buckets, collisions and hash codes.

Learn the difference between classes and interfaces once and for all, then get started declaring, implementing, and extending interfaces in your Java programs ...

How does the open-closed SOLID principle work in a Java program? Here we show you what this important principle means, and how to implement the open-closed principle in Java.

Learn how to use synchronous and asynchronous callbacks in Java—including callbacks with lambda expressions, CompletableFuture, and more.