J2SE
J2SE, which stands for Java 2 Platform, Standard Edition, was the predecessor to what is now known as the Java SE (Java Platform, Standard Edition). It represented a significant milestone in the evolution of the Java programming language and its platform. The "2" in J2SE indicated a major overhaul and enhancement of the Java platform, introducing a more robust and feature-rich environment for developing a wide range of applications.
The J2SE platform provided the core Java technologies and APIs necessary for building and running standalone
Key features introduced or significantly improved during the J2SE era included the Swing GUI toolkit, which