What is Java - How to install Java

The Java Runtime Environment (JRE) is software that allows for programs written in the Java programming language to run on your computer. “Minecraft Java Edition” is named as such because it is written in Java. Java comes in many shapes and forms, which may make it confusing exactly which version of it you should have installed, which is what this should hopefully explain.

We cannot use Oracle Java for modern versions of Java, since they have commercial usage restrictions which mean some users (particularly, those making money off of Minecraft) would have to pay to use it.

Fortunately, we can use OpenJDK, which is identical to Oracle Java but does not have the same restrictions. For this tutorial we will be using a version of OpenJDK built by Adoptium.

Quick links:

• Do I need Java? Which version do I need?
• Check if you have Java already
• Downloading and installing Java
• Appendix: Symptoms of incorrect Java version

Do I need Java? Which version do I need?

The Minecraft launcher includes the version(s) of Java required to run the game, and automatically keeps them up to date. This includes the Windows 7 and Windows 8.1 version of the launcher.

If you are using the official launcher, you normally do not have to manually install Java, but you may want to if you are trying to run a server, trying to fix an issue, or using it for Java applications other than Minecraft. If you are not are not sure if you are using the correct Minecraft launcher or are getting “This application requires a Java Runtime Environment” when launching Minecraft, then you can download the Minecraft Launcher from https://minecraft.net/download.

Note: Java versions 6 and 16 no longer receive security updates, and are therefore more risky to use. You should use any LTS version supported by Mojang if possible, as they will receive security updates for years to come.

The below compatibility chart was last updated 2024-09-08.

Verifying if Java is installed

You can check if a version of Java is already installed on your computer by following these instructions.

First, open up a terminal (Win11, macOS, Linux) or Command Prompt (Win10, Win8.1, Win7)

Next, type in java -version and press enter.

Java 8 will show up as either Java version "1.8. [...] or openjdk version "1.8. [...].

Java 11 will show up as either Java version "11. [...] or openjdk version "11. [...].

Java 17 will show up as either Java version "17. [...] or openjdk version "17. [...].

Java 21 will show up as either Java version "21. [...] or openjdk version "21. [...].

Downloading Java (OpenJDK)

There are many places where you can get OpenJDK, in this tutorial we will be getting them from Adoptium.

Note: If you are using Linux, most package managers include OpenJDK, so you do not need an installer for them. If this is the case, you can skip to installation instructions

Visit the website for Adoptium Temurin OpenJDK.

Select the version you want from the list and click “Latest release” to start the download. If the version you want is not listed, or if your operating system is incorrectly detected, you may have to click “Other platforms” and select from the list there. Make sure to download the MSI installer for Windows or the PKG installer for macOS.

Continue following the instructions for your platform below.

sudo apt install openjdk-21-jdk

sudo apt install openjdk-17-jdk

sudo apt install openjdk-11-jdk

sudo apt install openjdk-8-jdk

sudo dnf install java-21-openjdk.x86_64

sudo dnf install java-17-openjdk.x86_64

sudo dnf install java-11-openjdk.x86_64

sudo dnf install java-1.8.0-openjdk.x86_64

sudo pacman -S jdk21-openjdk

sudo pacman -S jdk17-openjdk

sudo pacman -S jdk11-openjdk

sudo pacman -S jdk8-openjdk

sudo yum install java-21-openjdk

sudo yum install java-17-openjdk

sudo yum install java-11-openjdk

sudo yum install java-1.8.0-openjdk

update-java-alternatives --list

sudo update-java-alternatives --set java-1.21.0-openjdk-amd64

sudo alternatives --config java

archlinux-java status

sudo archlinux-java set java-21-openjdk

Next steps

Additional info: Verifying if Java is installed properly

Additional info: Changing the default Java version used by the launcher

Appendix: Possible symptoms of incorrect Java version

Below are some of the error messages related to incorrect Java versions.

Error: A JNI error has occurred, please check your installation and try again

Exception in thread "main" java.lang.UnsupportedClassVersionError: net/minecraft/bundler/Main has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 55.0

Exception in thread "main" java.lang.UnsupportedClassVersionError: net/minecraft/bundler/Main has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 52.0

Exception in thread "main" java.lang.UnsupportedClassVersionError: net/minecraft/bundler/Main has been compiled by a more recent version of the Java Runtime (class file version 60.0), this version of the Java Runtime only recognizes class file versions up to 55.0

Exception in thread "main" java.lang.UnsupportedClassVersionError: net/minecraft/bundler/Main has been compiled by a more recent version of the Java Runtime (class file version 60.0), this version of the Java Runtime only recognizes class file versions up to 52.0

Your Java Runtime is incompatible. Please edit your installation to use the bundled Java Runtime.
Name: Java version mismatch

If you see any of the above messages, you need to update to Java 17.

(When attempting to launch Forge)
java.lang.ClassCastException: class jdk.internal.loader.ClassLoaders$AppClassLoader cannot be cast to class java.net.URLClassLoader (jdk.internal.loader.ClassLoaders$AppClassLoader and java.net.URLClassLoader are in module java.base of loader 'bootstrap')

If you see the above message, you need to downgrade to Java 8, because old Forge does not support Java 11+.

Note: Forge is not officially supported by Minecraft