There's an easy way to run Java in the browser now that WebAssembly is a W3C standard. In this Java and WebAssembly tutorial, we show you how to compile Java into WASM, and invoke your Java code in ...

Create packages, import packaged classes and interfaces into your programs, move packages, and encapsulate them in jar files.

The distinction is that the JDK is a package of tools for developing Java-based software, whereas the JRE is a package of tools for running Java code.