Ubuntu what is my java version

Как проверить версию Java

Java — один из самых популярных языков программирования в мире, используемый для создания различных типов кроссплатформенных приложений.

В этой статье объясняется, как с помощью командной строки проверить, какая версия Java установлена в вашей системе Linux. Это может быть полезно при установке приложений, требующих определенной версии Java.

Управление версиями Java

Java использует семантическое управление версиями . Версии готовых к выпуску релизов представлены по следующей схеме:

Например, в Java 11.0.8 11 — это основная версия, 0 — дополнительная версия, а 8 — версия безопасности.

• MAJOR — Основные выпуски содержат новые возможности и функции.
• MINOR — второстепенные выпуски содержат различные исправления ошибок и совместимые улучшения.
• SECURITY — выпуски безопасности содержат критические исправления безопасности.

Проверка версии Java

Чтобы узнать, какая версия Java установлена в вашей системе, выполните команду java -version :

Команда отобразит версию Java по умолчанию:

openjdk 11.0.8 2020-07-14 OpenJDK Runtime Environment (build 11.0.8+10-post-Ubuntu-0ubuntu120.04) OpenJDK 64-Bit Server VM (build 11.0.8+10-post-Ubuntu-0ubuntu120.04, mixed mode, sharing) 

В этом примере в нашей системе установлена Java версии 11.0.8 . Версия, установленная в вашей системе, может отличаться.

Если вы получили сообщение «java: command not found», это означает, что Java не установлена в системе. Чтобы установить Java, воспользуйтесь одним из следующих руководств в зависимости от вашего дистрибутива Linux:

В системе также может быть установлено несколько версий Java одновременно. Чтобы проверить, есть ли на вашем компьютере несколько установок Java:

sudo update-alternatives --config java

Если у вас только одна установка Java, результат будет выглядеть примерно так:

There is only one alternative in link group java (providing /usr/bin/java): /usr/lib/jvm/java-11-openjdk-amd64/bin/java Nothing to configure. 

В противном случае, если у вас несколько установок Java, команда отобразит меню, в котором вы можете выбрать, какая версия будет версией Java по умолчанию:

There are 3 choices for the alternative java (providing /usr/bin/java). Selection Path Priority Status ------------------------------------------------------------ * 0 /usr/lib/jvm/java-11-openjdk-amd64/bin/java 1111 auto mode 1 /usr/lib/jvm/java-11-openjdk-amd64/bin/java 1111 manual mode 2 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java 1081 manual mode Press to keep the current choice[*], or type selection number: 

Чтобы изменить версию Java по умолчанию, просто введите номер версии (число в столбце «Выбор») и нажмите Enter .

Выводы

Узнать, какая версия Java установлена в вашей системе Linux, очень просто, просто введите java -version .

Не стесняйтесь оставлять комментарии, если у вас есть вопросы.

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How to Check and Update Java Version on Ubuntu 22.04?

Java is a general-purpose client-side programming language that serves several functionalities like android application development, game development, web applications development, and many other software products. To build any application, first, we have to install Java on our computer systems. However, some applications are not capable to run on java’s outdated version. So, it’s essential to know which Java version is installed on our operating system and if our machine is running an outdated version of java, then how to update it.

This post will explain how to check and upgrade the Java version on Ubuntu 22.04. So, let’s begin!

How to check Java version on Ubuntu 22.04

Open the terminal on your ubuntu 22.04 operating system and type the below-mentioned command to check which Java version is installed on your machine:

Once you typed the above-given command on the terminal, it will produce the following outcome:

The above snippet shows that Java is not installed on our machine. Now, let’s move one step further to learn how to install/upgrade the Java version on Ubuntu 22.04.

How to Update Java version on Ubuntu 22.04

To update the java version or to install the latest java version, firstly you have to upgrade the apt repository. To do so, type the below-given command on the terminal:

Next, run the below-enlisted command to install the default Java Runtime Environment(JRE) on your operating system:

When you execute the above-given command, it will work like this:

Type “Y” to continue the installation process:

The whole installation process will take a few minutes to install JRE on your system. You can verify the JRE’s installation by typing the following command:

If JRE is successfully installed on your Ubuntu 22.04, then you will witness the result something like this:

Congratulations! You have successfully installed the latest and updated version of Java on Ubuntu 22.04.

As the JRE’s installation is done, now you can run almost every java software on your machine. However, some java-oriented software may require the Java Development Kit(JDK) to compile/run some particular tasks. In such cases, you can install the JDK by typing the below-given command:

The above-given command will work something like this:

Type “Y” to continue the JDK’s installation process:

Type the below-given command on the terminal of ubuntu 22.04 to verify whether the updated JDK is installed on your machine or not:

You will witness the below-given output:

Congrats! You are running an updated Java version on your ubuntu 22.04.

Conclusion

Open the terminal and type “sudo apt install default-jre” to install JRE, and type “sudo apt install default-jdk” to install JDK on ubuntu 22.04. To check or verify the java version type “java -version” on the terminal of Ubuntu 22.04. This write-up provided a step-by-step guide on how to check, update, and verify the java version on ubuntu 22.04.

About the author

Anees Asghar

I am a self-motivated IT professional having more than one year of industry experience in technical writing. I am passionate about writing on the topics related to web development.

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How to check Java Version on Linux Ubuntu

Java is a high-level, Object-Oriented programming language developed in 1995 by Sun Microsystems. Over time, Java has grown to become one of the most prominent high-level languages. It is now popular among app developers, financial, scientific, and estate enterprises. It is independent of the platform, open-source, versatile, and easy to learn and use.

It is practically a Turing-complete language so anything can be done on it. Most of the things one can do in Python can also be done in Java. Jpython is a Python version that runs on Java in the JVM (Java Virtual Machine). In this guide, we will dive into the procedure of looking up the Java version on Ubuntu Linux and install it if it is not already available.

Understanding the Java Version

The Java version is an indicator of the release of Java software currently under use by your OS.

It is highly recommended that the version be updated for better performance, stability, sophisticated features, and the latest security patches. This can go a long way and help you in preventing many unwanted issues and staying up to date.

Many websites, packages, or libraries require you to update to the latest Java version. So, it is preferred to stay one step ahead and have the latest release downloaded on your system. For instance, the latest Java version enables you to view 3D images along with other exciting features.

So, without further ado, let’s delve into the procedure of Java version verification and installation.

Checking Your Java Version

Start by checking your Java version. To do this, simply type the following in the terminal window.

This will give us the Java version that’s currently in use.

However, as evident from the picture above, Java isn’t installed on our system. But the terminal gives us options to install packages. Copying these commands and running them should get you the version installed directly via the terminal. All these versions are “headless”, meaning they don’t require a graphical user interface.

However, to download the latest release (16.02), you can use the browser method. Now, let’s go through the step-by-step process of installation.

Installing Java Using the Browser

Follow the steps to download Java.

Go to Google and search “download java JDK” and open the first link from the search results.

JDK is the “Java Development Kit” used to develop programs that run on Java. Alternatively, you can click on the link here to go directly to the page.

Under the “Java SE downloads”, go to “Java SE 16” as that is the latest version. The next step is to download JDK.

Scroll through the packages till you find the “Linux x64 Debian Package”. Download the file next to it. Ubuntu uses Debian packages to install programs, so you’ll see that the file has a .deb extension.

Once you are done with the download, open the folder where the downloaded package is located. Right-click anywhere in the window and select “Open in Terminal”.

Type the following command in the terminal to start unpacking the downloaded package.

You can replace the highlighted part of the command with the name of the package corresponding to the Java version you downloaded.

Having done that, you can type in the following command to confirm that Java is installed on your system.

With that out of the way, set your package as the alternative. To do that, use the following command:

$ sudo update-alternatives – install / usr / bin / java java / usr / lib / jvm / jdk-16.0.2 / bin / java 1

Now, we can finally check and verify our version by typing the following:

To install the compiler, just use the same command as before, only this time replace “java” with “javac”.

$ sudo update-alternatives – install / usr / bin / javac javac / usr / lib / jvm / jdk-16.0.2 / bin / javac 1

To check the Javac version, type the following command:

Additionally, to set the java_home path, enter the following:

$ sudo update-a;ternatives —config java

$ sudo gedit / etc / environment

Once the text editor opens, paste the copied line and assign it to “JAVA_HOME” as demonstrated below.

Once this is done, clear the screen and type in the following commands to complete the process of Java home path configuration.

Some Important Commands

Given below are certain commands you can use to check your version alongside other important things.

(This command shows all the Java versions installed on your system.)

(Shows Java version you are using.)

(Shows version of Java you are currently using.)

(Shows the version of Java compiler.)

(To find the location of Java.)

Remove Java Versions

To remove Java from your system, you can type in the following command:

Press “Y” followed by “ENTER” and the package will be uninstalled.

Should You Use JRE or JDK?

To run Java programs, you’ll need JRE (Java runtime environment). It is compatible with Windows, Linux, Mac, Solaris, and many more.

JDK (Java Development Kit) is used to develop Java applications. It is usually where most programmers start from. It depends on what you want to do.

When to Use JDK

• You want to write Java programs. It comes with a compiler and Java application launcher.
• Has access to the main Java libraries for coding via Java application launcher which opens JRE.

When to Use JRE

• You have to use libraries and other files. It does not have compiler and error detection agents of its own.
• When you have to use utility packages like math or data related sets and instructions.
• To run applications running on Java.

Some Applications of Java

• Building Android applications.
• In developing web and cloud applications.
• Software tools like Eclipse and Netbeans.
• Chatbots.
• Games.
• Scientific and Enterprise applications

Conclusion

To stay up to date and get a hands-on experience of the latest packages and software, keeping our programs updated is a must. This check and balance can really help us a long way in keeping our system efficient, protected, and up to date.

About the author

Zeeman Memon

Hi there! I’m a Software Engineer who loves to write about tech. You can reach out to me on LinkedIn.

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