Run jdk in linux

Run jdk in linux

This topic describes the installation procedures of the JDK on the Linux platform, along with the system requirements.

General Notes About Installing the JDK on Linux Platforms from Archive Files

Installing the JDK automatically creates a directory called jdk–feature.interim.update.patch where feature ( 20 ),interim, update, and patch represent corresponding values of version information.

If you install JDK in a specific location such as /opt , you must log in with root credentials to gain the necessary permissions. If you do not have the root access, either install the JDK in your home directory or a sub directory for which you have the write permissions.

If you install the software in a directory that contains a sub directory named jdk– 20 .interim.update.patch , the new software overwrites files of the same name in that directory. Ensure that you rename the old directory if it contains files that you would like to keep.

Installing the JDK from archive files doesn’t configure the backing store for the system node of Java Preferences API ( java.util.prefs Java package). If this functionality of the JDK is required, you need to manually configure it by making sure either /etc/.java/.systemPrefs or jdk– 20 .interim.update.patch/.systemPrefs directory exists.

General Notes About Installing the JDK on Linux Platforms from RPM packages

This topic describes general information about installing JDK 20 from RPM packages on Linux platforms.

You can install only one version of JDK of the same feature release. If you try to install the newer version of the same feature release while the older version exists, the installer uninstalls the older version and installs the new version. For example, you can’t install jdk- 20 and jdk- 20 .0.1 simultaneously. If you attempt to install jdk- 20 .0.1 after jdk- 20 is installed, the installer uninstalls jdk- 20 and installs jdk- 20 .0.1 .

All versions of JDK of the same feature release are installed in /usr/lib/jvm/jdk- 20 -oracle- directory, where equals x64 or aarch64 . Additionally /usr/java/jdk- 20 symbolic link pointing to the installation directory is created for backward compatibility.

If you install an older version of a JDK when the newer version of the same feature family already exists, an error is displayed, prompting you to uninstall a newer JDK version if an older version has to be installed.

You must log in with root credentials to install or update JDK.

By default, the installation script configures the system such that the backing store for the system node of Java Preferences API (java.util.prefs Java package) is configured in /etc/.java/.systemPrefs directory.

The JDK installation is integrated with the alternatives framework. After installation, the alternatives framework is updated to reflect the binaries from the recently installed JDK. Java commands such as java , javac , javadoc , and javap can be called from the command line.

Using the java -version command, you can confirm the default (recently installed) JDK version.

System Requirements for Installing JDK on Linux Platforms

See Oracle JDK Certified Systems Configurations for information about supported platforms, operating systems, and browsers.

Installing the JDK on Linux from Archive Files, RPM Packages and Oracle Linux Repositories

You can install the JDK on a Linux platform from archive files, downloadable Red Hat Package Manager (RPM) packages files, or RPM packages from Oracle Linux (OL) repositories.

Installation can be performed by using one of the following processes:

• From archive files ( .tar.gz ): This allows you to install a private version of the JDK for the current user into any location, without affecting other JDK installations. However, it may involve manual steps to get some of the features to work. See the following table for the options available for downloading and installing the JDK from archive files. The bundles are available for Linux x64 and Linux aarch64 (64-bit ARM) systems. Install the required bundle.
• From downloadable RPM packages ( .rpm ): This allows you to perform a system-wide JDK installation on RPM-based Linux platforms for all users, and requires root access. See the following table for the options available for downloading and installing the JDK from Linux x64 and Linux aarch64 (64-bit ARM) RPM packages.
• From Oracle Linux repositories : This allows you to perform a system-wide JDK installation on OL platforms starting from OL7 for all users, and requires root access. JDK RPM packages in Oracle Linux RPM repositories are available for x64 and aarch64 (64-bit ARM) OL platforms. Explicit download of JDK RPM packages is not required, the package manager will do it automatically for you.

JDK RPM packages for Generic Linux platforms and Oracle Linux platforms differ. The following table lists the differences:

Table 3-1 Difference between Generic Linux and OL platforms

JDK image is split into two packages: jdk- 20 -headless and jdk- 20 -headful .

• jdk- 20 -headless is a headless Java Runtime for running non-GUI applications.
• jdk- 20 -headful is headful Java Runtime and Development Tools for developing and running all types of applications.

jdk- 20 -headful package requires jdk- 20 -headless package. When these packages are installed together, they provide the same functionality as the jdk- 20 package for Generic Linux Platforms.

jdk- 20 -headless package registers java group with the alternatives framework.

jdk- 20 -headful package registers javac group with the alternatives framework.

Downloading the JDK Installer

Access Java SE Downloads page and click Accept License Agreement . Under the Download menu, click the Download link corresponding your requirement.

The following table lists the options and instructions for downloading and installing the JDK 20 release on a Linux platform:

Download File	Instructions	Architecture (CPU Type)	Who Can Install
For Linux x64 systems: jdk- 20 .interim.update.patch_linux-x64.tar.gz	Installing the 64-Bit JDK on Linux Platforms	Intel — 64-bit	Anyone
For Linux aarch64 (64-bit ARM) systems: jdk- 20 .interim.update.patch_linux-aarch64.tar.gz	Installing the 64-Bit JDK on Linux Platforms	ARM — 64-bit	Anyone
For Linux x64 systems: jdk- 20 .interim.update.patch_linux-x64.rpm	Installing the 64-Bit JDK on RPM-Based Linux Platforms	Intel — 64-bit RPM-based Linux	Root
For Linux aarch64 (64-bit ARM) systems: jdk- 20 .interim.update.patch_linux-aarch64.rpm	Installing the 64-Bit JDK on RPM-Based Linux Platforms	ARM — 64-bit RPM-based Linux	Root

Installing the 64-Bit JDK on Linux Platforms

You can install the JDK for 64-bit Linux from an archive file ( .tar.gz ). The .tar.gz archive file (also called a tarball) is a file that can be uncompressed and extracted in a single step.

• For Linux x64 systems: jdk- 20 .interim.update.patch_linux-x64_bin.tar.gz . For example jdk- 20 _linux-x64_bin.tar.gz
• For Linux aarch64 (64-bit ARM) systems: jdk- 20 .interim.update.patch_linux-aarch64_bin.tar.gz . For example, jdk- 20 _linux-aarch64_bin.tar.gz

Before you download a file, you must accept the license agreement. Anyone (not only root users) can install the archive file in any location having write access.

Installing the 64-Bit JDK on RPM-Based Linux Platforms

You can install the JDK on 64-bit RPM-based Linux platforms, such as Red Hat and SuSE by using a downloadable RPM package file ( .rpm ) in the system location.

You can install the JDK using a downloadable RPM package file on an OL system too, but the preferred way to install the JDK on OL systems is from Oracle Linux RPM repositories.

Ensure that you have the root user access. You can do this by running the command su and entering the superuser password.

• For x64 systems: jdk- 20 .interim.update.patch_linux-x64_bin.rpm . For example, jdk- 20 _linux-x64_bin.rpm
• For aarch64 (64-bit ARM) systems: jdk- 20 .interim.update.patch_linux-aarch64_bin.rpm . For example, jdk- 20 _linux-aarch64_bin.rpm

Before you download a file, you must accept the license agreement.

Upgrade the required package using the following command: $ sudo rpm -Uvh jdk- 20 _linux-x64_bin.rpm OR $ sudo rpm -Uvh jdk- 20 _linux-aarch64_bin.rpm

Note: JDK 20 can coexist with other feature releases of JDK. For each feature release, a separate directory is created, the default directory being /usr/lib/jvm/jdk- -oracle- . For example, JDK 20 releases for x64 will be installed in /usr/lib/jvm/jdk- 20 -oracle-x64 directory.

Installing the 64-Bit JDK on Oracle Linux Platforms

There are two OL-specific JDK RPM packages, jdk- 20 -headless and jdk- 20 -headful . When these packages are installed together, they provide full JDK functionality.

Install jdk- 20 -headless package if you only need headless Java Runtime for running non-GUI applications.

Install jdk- 20 -headful package if you need full JDK functionality for running any Java application and development.

The jdk- 20 -headful package depends on jdk- 20 -headless , hence installing jdk- 20 -headful package will result in the automatic installation of jdk- 20 -headless , if it is not installed yet.

sudo dnf install jdk- 20 -headless

sudo yum install jdk- 20 -headless

sudo dnf install jdk- 20 -headful

sudo yum install jdk- 20 -headful

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How to Run Java Programs in Ubuntu

So, you have started learning Java programming? That’s good.

And you want to run the java programs on your Linux system? Even better.

Let me show how to run Java in terminal in Ubuntu and other Linux distributions.

Running Java programs in Ubuntu

Let’s go in proper steps here.

Step 1: Install Java compiler

To run a Java program, you need to compile the program first. You need Java compiler for this purpose.

The Java compiler is part of JDK (Java Development Kit). You need to install JDK in order to compile and run Java programs.

First, check if you already have Java Compiler installed on your system:

If you see an error like “Command ‘javac’ not found, but can be installed with”, this means you need to install Java Development Kit.

The simplest way to install JDK on Ubuntu is to go with the default offering from Ubuntu:

sudo apt install default-jdk

You’ll be asked to enter your account’s password. When you type the password, nothing is seen on the screen. That is normal. Just enter your password blindly. When asked, press the enter key or Y key.

The above command should work for other Debian and Ubuntu based distributions like Linux Mint, elementary OS etc. For other distributions, use your distribution’s package manager. The package name could also be different.

Once installed, verify that javac is available now.

Step 2: Compile Java program in Linux

You need to have a Java program file for this reason. Let’s say you create a new Java program file named HelloWorld.java and it has the following content:

You can use Nano editor in terminal or Gedit graphical text editor for writing your Java programs.

If there is no error, the above command produces no output.

When you compile the Java program, it generates a .class file with the class name you used in your program. You have to run this class file.

Step 3: Run the Java class file

You do not need to specify the class extension here. Just the name of the class. And this time, you use the command java, not javac.

This will print Hello World on the screen for my program.

And that’s how you run a Java program in the Linux terminal.

This was the simplest of the example. The sample program had just one class. The Java compiler creates a class file for each class in your program. Things get complicated for bigger programs and projects.

This is why I advise installing Eclipse on Ubuntu for proper Java programming. It is easier to program in an IDE.

I hope you find this tutorial helpful. Questions or suggestions? The comment section is all yours.

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