How to restart java app managed by systemd on OutOfMemory errors
Like Fildor say I suggest you fix the memory problems.
After that a possible solution is:
If you are using Java prior 8u92 you can add to the JVM the following argument:
java -jar <jar-name> -XX:OnOutOfMemoryError="kill -9 %p"
in Java version 8u92 or higher you can use -XX:+CrashOnOutOfMemory or -XX:+ExitOnOutOfMemoryError
Then configure your service to restart on crash:
Restart=on-failure
or
Restart=always