Java is needed to run Sponge and Minecraft. You most likely already have Java, but you may need to update it.
Sponge requires Java 8 (specifically
1.8.0_40 or above) at this time. Older Java versions are deprecated and will not
work with Sponge. The difference between major versions of Java (6, 7, 8) is significant, and older versions cannot run
If you have Windows or macOS for your computer, you can download Java from the official website.
Linux users can install OpenJDK via their package manager. OpenJDK is the open source version of the Oracle version of Java, and it should work just as well, if not better. However, it’s also possible to download the Oracle version for Linux, but be aware that many Java-dependent Linux packages will still install OpenJDK anyway.
32-bit vs. 64-bit¶
If your computer supports it, you should use 64-bit versions of Java whenever possible. The Java installers from the linked website should detect whether your computer is ready for 64-bit.
Because the 64-bit version of Java runs considerably better, and also lets Java use more than ~3 GB of your RAM (memory), we always recommend it over 32-bit.
Most modern computers support 64-bit.
JDK vs. JRE¶
The JRE (Java Runtime Environment) is used to run Java applications. The download page linked above provides the JRE.
The JDK (Java Development Kit) is used to create Java applications, and you do not need it unless you plan to make Sponge plugins or work on Sponge. However, in some cases, you may need the JDK to diagnose a running Java application such as Sponge. You can download the JDK from a different site.