First of all, you should download a Java development kit (JDK), containing the Java virtual machine (JVM) and other resources for developing Java applications. Since LITIENGINE has been created with Java 8, you need at least JDK 8 on your machine.
In case you are on linux or mac, you can also use SKDMAN! to manager your JDK installation. Once you've installed sdk man, type
sdk install javain your terminal. The latest recommend JDK will be installed automatically for you. It should be registered in your IDE after you restart it. For further information look up the SDKMAN! Docs.
The official Oracle JDK has seen some severe licensing changes in 2019, requiring a paid license for developing commercial applications!
Here is a short overview over some entirely free JDK distributions:
|AdoptOpenJDK||JDK 8, JDK 11, JDK 15|
|Amazon Correto||JDK 8, JDK 11, JDK 15|
|Oracle Open JDK||JDK 15|
|Red Hat OpenJDK||JDK 8, JDK 11, JDK 15|