# Java21 Upgrade (Linux)

This article describes the steps to upgrade Java to version 21 on a Linux machine. It outlines the installation process, configuration updates, and validation steps required to ensure the system uses the correct Java version. The procedure follows a structured approach aligned with standard deployment practices.

## Prerequisites

* Linux-based system with root or sudo access
* Access to a package manager (e.g., yum)
* Existing Java installation on the system
* Terminal or command-line access

## Steps Involved

### Verify Existing Java Version

* Run the following command to check the currently installed Java version:

  ```
  java -version
  ```

  \
  Sample Reference Screenshot:

  <figure><img src="/files/jKUdsg4YGCqqbZO9rZOu" alt=""><figcaption></figcaption></figure>

### Install Java 21

* Execute the following command to install Java 21:

  ```
  sudo yum install java-21-openjdk-devel -y
  ```

  \
  Sample Reference Screenshot:

  <figure><img src="/files/jkjo0In9W5Ba6FZQTOtQ" alt=""><figcaption></figcaption></figure>

### Configure Java Alternatives

* Run the following command to list and configure available Java versions:&#x20;

  ```
  sudo update-alternatives --config java
  ```
* From the displayed list, select Java 21 by entering the corresponding number, then press Enter.\
  \
  Sample Reference Screenshot:

  <figure><img src="/files/P0FuovAs38KMzD1VemmF" alt=""><figcaption></figcaption></figure>

### Validate Java Upgrade

* Verify that the system is using Java 21 by running:

  ```
  java -version
  ```

  \
  Sample Reference Screenshot:

  <figure><img src="/files/su6ZkGAKidyBpCiqROJ5" alt=""><figcaption></figcaption></figure>

***

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