Java is a widely used programming language that powers a lot of applications and websites. If you’re using Ubuntu, it’s likely that you have Java installed on your system. In this article, we will guide you through the process of checking and uninstalling Java versions on Ubuntu.
To check Java versions on Ubuntu, you can use the
java -version, and
java -showversion commands. To uninstall a specific Java version, such as OpenJDK 6, you can use the
sudo apt-get remove openjdk-6-* icedtea-6-* command. Always check for dependencies before uninstalling any packages.
Checking Java Versions
To determine which Java versions are installed on your system, you can use a series of commands. Let’s go through them one by one.
update-java-alternatives -l Command
You can use the
update-java-alternatives -l command to display all the Java versions installed on your system. The
-l option stands for list, which will list all the Java alternatives in your system.
java -version Command
java -version command will show you the Java version currently in use. The
-version option is used to output version information.
java -showversion Command
java -showversion command will display the Java version in use along with additional information. The
-showversion option is used to provide more detailed version information.
Checking Java Alternatives
Ubuntu uses an “alternatives” system to manage different versions of applications. You can use the following commands to check the Java virtual machine and compiler:
file /etc/alternatives/java /etc/alternatives/javac Command
This command will show you what is currently providing the Java virtual machine (
java) and the Java compiler (
file /etc/alternatives/java /etc/alternatives/javac
file which java javac“ Command
This command will check if the alternatives system is working properly and being used by Java. The
which command is used to locate the executable file associated with the given command.
file `which java javac`
Uninstalling Java Versions
If you want to uninstall a specific version of Java, such as OpenJDK 6, you can use the command-line. Run the following command:
sudo apt-get remove openjdk-6-\* icedtea-6-\*
sudo command is used to execute the command as an administrator. The
apt-get remove command is used to remove the specified packages. The
icedtea-6-\* are the packages to be removed.
Before removing any
openjdk-6- packages, it is recommended to simulate the removal operation to check for any dependencies. You can do this by running:
apt-get -s remove openjdk-6-\* icedtea-6-\*
-s option stands for simulate, which will simulate an operation but not actually perform it. This is useful for checking the potential impact of a command without actually executing it.
If you want to continue using Java content online in your web browser, make sure to have the corresponding
icedtea-7- packages installed before removing any
In this article, we’ve covered how to check and uninstall Java versions on Ubuntu. Remember to always check for dependencies before uninstalling any packages to avoid breaking your system. If you have any questions or run into any issues, feel free to leave a comment below.
To check if Java is installed on your Ubuntu system, you can use the
java -version command in the terminal. This command will display the Java version if it is installed.
You can use the
update-java-alternatives -l command to list all the Java versions installed on your Ubuntu system.
You can use the
file /etc/alternatives/java /etc/alternatives/javac command to check which Java virtual machine (
java) and Java compiler (
javac) are currently being used on your Ubuntu system.
To uninstall a specific version of Java, such as OpenJDK 6, you can use the command
sudo apt-get remove openjdk-6-* icedtea-6-* in the terminal. This command will remove the specified Java packages.
Yes, it is recommended to simulate the removal operation before uninstalling Java packages. You can do this by running
apt-get -s remove openjdk-6-* icedtea-6-*. The simulation will help you check for any dependencies and potential impact of the removal operation without actually executing it.
If you want to continue using Java content online in your web browser after uninstalling Java packages, make sure to have the corresponding
icedtea-7-* packages installed before removing any
openjdk-6-* packages. This will ensure that your web browser can still run Java applets and other Java-based content.