Java

Hello World in Java

Every programming journey starts with Hello World. Let’s write our first Java program.

The Code

Create a file named HelloWorld.java:

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public class HelloWorld {
    public static …

Variables and Types in Java

Java is a statically typed language, which means every variable must be declared with a specific type before it can be used. The compiler enforces these types at compile time, catching type errors …

Operators in Java

Operators are the workhorses of every Java expression. They combine values, compare them, and update state — and because Java is a statically and strongly typed language, the type of each operand …

Control Flow in Java

Control flow is how a program decides what to do next. Instead of running every line top to bottom, control flow lets your code branch based on conditions and repeat work with loops. Mastering it is …

Functions in Java

In Java, the unit of reusable behavior is the method. Because Java is an object-oriented, class-based language, there are no free-standing functions the way there are in C or Python — every method …

Channels, Actors, and Goroutines: The Concurrency Models That Divided Language Design

In 1973, Carl Hewitt published a paper describing something he called the Actor model — isolated computational units that communicated exclusively by message passing, with no shared memory, no locks, …

The Many Ways to Fail: Error Handling Philosophies Across Programming Languages

Every program that has ever run has eventually encountered something unexpected. A file that wasn’t there. A network that dropped the connection. A number that divided by zero. A user who typed …

Who Taught Your Language to Remember? A Tour of Memory Management

In our three-part series on web backend performance, we measured idle memory ranging from 3 MB (Rust) to 500 MB (Spring Boot). We noted that a garbage collector explained much of Java’s …

The Billion-Dollar Mistake, 60 Years Later: How Languages Handle Null

In 2009, Tony Hoare stood at the QCon conference in London and confessed to a crime.

“I call it my billion-dollar mistake,” he said. “It was the invention of the null reference in …

Strings Are Not Simple: How 12 Languages Model Text (And Why They Disagree)

Every programming language has strings. They’re so universal — so unremarkable — that we rarely stop to ask how they actually work. You type some characters between quotation marks, hand them to …