Official Java status
Mojang announced a future Java and Bedrock release but has not published a complete Java feature list or confirmed a precise release date. Dungeons II footage is not a Java snapshot.
Can I play it now?
The confirmed route inside Java today is a community mod. Do not mistake an author’s portal, biome, mob or material for Mojang’s upcoming vanilla implementation. Check official snapshot notes before treating any Java preview as the Sift update.
The community route
Mielon’s The Sift has published separate files for 26.3 Fabric, 26.2 Fabric, 1.21.1 NeoForge, and 1.20.1 Forge in the captured Modrinth metadata. The project-wide loader list combines all files and does not mean every loader works with every Minecraft version.
Before installing
Create a separate profile and back up important worlds. Match the exact Minecraft version, loader and required dependency release to a specific mod file. Use the exact author file page on Modrinth or CurseForge rather than a rehosted .jar.