I'm developing mod for Minecraft Forge 1.17 which requires JDK16. I have installed that. I'm using Eclipse and the compiler gives a warning that execution environment is JavaSE16 but no JRE16 found. As far as I know there is no JRE16 installed on my computer. The problem is that I can't find it anywhere.
Looked from Oracle website and Adoptium website. Both offer JDK16, but no JRE16. Where can I find JRE16 to download?
Understand that a JDK is a superset of a JRE. A JDK = a JRE + a compiler and other tools.
Java 16 is now past end-of-life.
I suggest you move to Java 17, the current long-term support version. You should read the release notes for Java 17. But as I recall migrating from 16 to 17 should be quite simple, without issues.
Several vendors offer binaries and installers for the JDK. Some of those release a JRE as well.
The lost of potential vendors include Adoptium, Azul Systems, Microsoft, IBM, Red Hat, BellSoft, SAP, Oracle, Pivotal, Amazon, and more.
Some vendors may offers builds for the outdated Java 16. For example, Azul Systems offers a JRE for Java 16. But such outdated versions are intended only for debugging, not production.