Installing the JDK

Writing and running Java requires the JDK (Java Development Kit), which bundles the compiler (javac), the runtime (java), and the standard library. This course uses Java 21, the current long-term-support (LTS) release.

Download a JDK build (Eclipse Temurin and Oracle's own builds are both free) and confirm the install:

java --version
javac --version

Both should report 21 (or later). If java isn't found, the JDK's bin folder needs to be added to your system's PATH.