Manage Java

Most tools never need this page, because installing a loader finds Java for you. Use modsmith.java when you want to choose a runtime yourself or show it to the player.

Mojang publishes Java as named components, such as java-runtime-delta.

Find what a version needs

import modsmith as ms

game = ms.minecraft.GameDir.default()
ms.minecraft.install_version(game, "1.21.1")

component = ms.java.required_for(game.version("1.21.1"), game)
print(component)

Find or download a runtime

find looks in the official launcher and in Modsmith’s cache:

runtime = ms.java.find(component, game=game)

download fetches a runtime into Modsmith’s cache. It never changes the launcher’s folder.

if runtime is None:
    runtime = ms.java.download(component)

print(runtime.executable)

find_all lists every runtime that is installed:

for runtime in ms.java.find_all(game=game):
    print(runtime.component, runtime.executable)

Not every runtime exists everywhere

Mojang does not publish every component for every system. For example, jre-legacy has no build for Apple Silicon, so download raises modsmith.errors.JavaError there.

print(ms.java.platform_key())