How to install Java SDK on CentOS?

1. Update System Packages: First, ensure your system is up to date. Open a terminal and execute the following command:

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sudo yum update

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2. **Check if Java is Installed:**
   Before installing the new Java SDK, verify whether Java is already installed on your system. Run the following command:

java -version

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   If Java is installed, this command will display the current version.

3. **Download Java SDK:**
   Next, decide which Java SDK version to install—either from the Oracle website or OpenJDK. The example below uses OpenJDK.
   To install OpenJDK, use CentOS's package manager `yum`. For instance, to install OpenJDK 11, run:

sudo yum install java-11-openjdk-devel

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   If you prefer Oracle JDK, download it from the Oracle website. Due to licensing requirements, you may need to accept the license agreement and register before downloading.

4. **Set Environment Variables:**
   To run Java and Javac from any location, configure the JAVA_HOME environment variable. First, identify the Java installation path:

sudo update-alternatives --config java

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   Note the installation path. Then, open `/etc/profile` or your user's configuration files (e.g., `.bash_profile`, `.bashrc`, or `.zshrc`), and add:

export JAVA_HOME=/path/to/your/java export PATH=$PATH:$JAVA_HOME/bin

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   Replace `/path/to/your/java` with the actual path found earlier.

5. **Verify Installation:**
   After saving and closing the file, reload the configuration or restart your terminal. Then run these commands to confirm successful installation and configuration:

java -version javac -version

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   Both commands should return the installed Java version.

The steps above provide the basic process for installing Java SDK on CentOS. If you require a specific Oracle JDK version or have unique configuration needs, the process may differ slightly.