Engine Installation

Zernyth's Java integration is built from source inside the Endstone fork and is opt-in at build time and at runtime. Without the runtime opt-in, no Java loader is registered and no JVM is started.

Build

You need the existing Endstone build environment, a JDK 25 with JNI headers, and Gradle 9.1 or newer.

Add -DENDSTONE_ENABLE_JAVA=ON to the native CMake configuration. The default is off.
In the java/ directory, build the JARs:

gradle --offline --no-daemon :api:jar :runtime:jar :example:jar

Enable at runtime

Variable	Value
`ZERNYTH_JAVA_ENABLED`	`1`
`ZERNYTH_JVM_LIBRARY`	Absolute path to `jvm.dll` (`JAVA_HOME/bin/server/jvm.dll`) or `libjvm.so` (`JAVA_HOME/lib/server/libjvm.so`). The architecture must match the server.
`ZERNYTH_JAVA_CLASSPATH`	API and runtime JARs, separated by `;` on Windows and `:` on Linux.

Plugin JARs go into the existing plugins folder.

When something is wrong

Java candidates with a faulty configuration are rejected with a diagnostic, and the other plugin loaders stay active. A failed JVM start is not retried inside the process, so restart the process after correcting the configuration.

Published engine builds, when available, are listed on the downloads page.