How To Install Openjdk 8 On Ubuntu 18.04

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Introduction

Java and the JVM (Java's virtual machine) are required for many kinds of software, including Tomcat, Jetty, Glassfish, Cassandra and Jenkins.

In this guide, you volition install various versions of the Coffee Runtime Environment (JRE) and the Java Programmer Kit (JDK) using apt. You'll install OpenJDK as well as the official JDK from Oracle. You'll then select the version you wish to use for your projects. When you're finished, you'll be able to use the JDK to develop software or use the Java Runtime to run software.

Prerequisites

To follow this tutorial, you will need:

• One Ubuntu 18.04 server set up by following the the Ubuntu 18.04 initial server setup guide tutorial, including a sudo non-root user and a firewall.

Installing the Default JRE/JDK

The easiest option for installing Java is to employ the version packaged with Ubuntu. By default, Ubuntu xviii.04 includes Open up JDK xi, which is an open up-source variant of the JRE and JDK.

To install this version, get-go update the package alphabetize:

                      
              
                sudo                apt                update              
            
                  

Next, check if Java is already installed:

                      
              
coffee -version              
            
                  

If Java is not currently installed, you'll see the following output:

                      
Output
Command 'java' not found, only can be installed with:  sudo apt install default-jre sudo apt install openjdk-eleven-jre-headless sudo apt install openjdk-8-jre-headless                  

Execute the following control to install the default Java Runtime Surround (JRE), which volition install the JRE from OpenJDK eleven:

                      
              
                sudo                apt                install                default-jre              
            
                  

The JRE will allow you to run almost all Coffee software.

Verify the installation with:

                      
              
coffee -version              
            
                  

You lot'll meet output like to the post-obit:

                      
Output
openjdk version "11.0.11" 2022-04-20 OpenJDK Runtime Environment (build xi.0.eleven+nine-Ubuntu-0ubuntu2.18.04) OpenJDK 64-Bit Server VM (build xi.0.xi+ix-Ubuntu-0ubuntu2.xviii.04, mixed mode, sharing))                  

You may need the Java Evolution Kit (JDK) in addition to the JRE in social club to compile and run some specific Java-based software. To install the JDK, execute the following command, which will also install the JRE:

                      
              
                sudo                apt                install                default-jdk              
            
                  

Verify that the JDK is installed by checking the version of javac, the Java compiler:

                      
              
javac -version              
            
                  

You'll see the following output:

                      
Output
javac            xi.0.11                  

Next, allow's look at how to install Oracle'south official JDK and JRE.

Installing Oracle JDK 11

Oracle'due south licensing agreement for Coffee doesn't let automatic installation through packet managers. To install the Oracle JDK, which is the official version distributed past Oracle, you must create an Oracle account and manually download the JDK to add a new package repository for the version you'd similar to use. And then yous tin use apt to install it with help from a third political party installation script.

The version of Oracle'south JDK you lot'll need to download must match version of the installer script. To discover out which version you lot demand, visit the oracle-java11-installer page.

Locate the package for Bionic, as shown in the following effigy:

In this prototype, the version of the script is eleven.0.7. In this case, you lot'll demand Oracle JDK eleven.0.7. Y'all don't need to download annihilation from this page; y'all'll download the installation script through apt shortly.

Then visit the Downloads page and locate the version that matches the ane y'all demand.

Click the JDK Download button and you'll be taken to a screen that shows the versions available. Click the .tar.gz bundle for Linux.

You'll be presented with a screen asking you to have the Oracle license agreement. Select the checkbox to accept the license agreement and press the Download button. Your download will begin. You lot may demand to log in to your Oracle account one more than time before the download starts.

Once the file has downloaded, you'll need to transfer it to your server. On your local machine, upload the file to your server. On macOS, Linux, or Windows using the Windows Subsystem for Linux, use the scp command to transfer the file to the abode directory of your sammy user. The post-obit command assumes you've saved the Oracle JDK file to your local machine'southward Downloads binder:

                      
              
                scp                Downloads/jdk-11.0.7_linux-x64_bin.tar.gz                sammy@your_server_ip:~              
            
                  

Once the file upload has completed, return to your server and add together the third-party repository that volition help you install Oracle's Java.

Install the software-properties-common package, which adds the add-apt-repository command to your system:

                      
              
                sudo                apt                install                software-properties-common              
            
                  

Adjacent, import the signing primal used to verify the software y'all're well-nigh to install:

                      
              
                sudo                apt-cardinal adv --keyserver keyserver.ubuntu.com --recv-keys EA8CACC073C3DB2A              
            
                  

You'll come across this output:

                      
Output
gpg: key EA8CACC073C3DB2A: public key "Launchpad PPA for Linux Insurgence" imported gpg: Total number processed: 1 gpg:               imported: 1                  

Then use the add-apt-repository control to add the repo to your listing of packet sources:

                      
              
                sudo                add-apt-repository ppa:linuxuprising/java              
            
                  

You'll run across this message:

                      
Output
            Oracle Java 11 (LTS) and 12 installer for Ubuntu, Linux Mint and Debian.  Java binaries are not hosted in this PPA due to licensing. The packages in this PPA download and install Oracle Java eleven, so a working Net connexion is required.  The packages in this PPA are based on the WebUpd8 Oracle Java PPA packages: https://launchpad.net/~webupd8team/+archive/ubuntu/java  Created for users of https://www.linuxuprising.com/  Installation instructions (with some tips), feedback, suggestions, problems reports etc.:  . . .  Press [ENTER] to continue or ctrl-c to cancel calculation information technology                  

Printing ENTER to continue the installation. Yous may run into a message about no valid OpenPGP data institute, but you can safely ignore this.

Update your package list to make the new software available for installation:

                      
              
                sudo                apt                update              
            
                  

The installer volition look for the Oracle JDK you downloaded in /var/cache/oracle-jdk11-installer-local. Create this directory and motility the Oracle JDK archive there:

                      
              
                sudo                mkdir                -p /var/cache/oracle-jdk11-installer-local/              
              
                sudo                cp                jdk-11.0.7_linux-x64_bin.tar.gz /var/cache/oracle-jdk11-installer-local/              
            
                  

Finally, install the package:

                      
              
                sudo                apt                install                oracle-java11-installer-local              
            
                  

The installer will get-go ask you lot to accept the Oracle license agreement. Accept the agreement, then the installer will excerpt the Java package and install it.

Now let'due south look at how to select which version of Java yous want to use.

Managing Java

You lot can take multiple Java installations on one server. You lot can configure which version is the default for apply on the command line by using the update-alternatives control.

                      
              
                sudo                update-alternatives --config java              
            
                  

This is what the output would wait like if yous've installed both versions of Coffee in this tutorial:

                      
Output
In that location are 2 choices for the alternative java (providing /usr/bin/java).    Selection    Path                                         Priority   Condition ------------------------------------------------------------   0            /usr/lib/jvm/java-11-openjdk-amd64/bin/coffee   1111      auto way   1            /usr/lib/jvm/java-xi-openjdk-amd64/bin/java   1111      manual mode * ii            /usr/lib/jvm/java-eleven-oracle/bin/coffee          1091      transmission mode  Press <enter> to continue the current choice[*], or type selection number:                  

Choose the number associated with the Java version to use it as the default, or press ENTER to leave the electric current settings in place.

You tin can do this for other Java commands, such as the compiler (javac):

                      
              
                sudo                update-alternatives --config                javac              
            
                  

Other commands for which this command can be run include, but are not express to: keytool, javadoc and jarsigner.

Setting the JAVA_HOME Environment Variable

Many programs written using Java use the JAVA_HOME environment variable to determine the Java installation location.

To set this environment variable, kickoff determine where Java is installed. Utilize the update-alternatives command:

                      
              
                sudo                update-alternatives --config java              
            
                  

This command shows each installation of Java forth with its installation path:

                      
Output
There are two choices for the alternative java (providing /usr/bin/java).    Selection    Path                                         Priority   Status ------------------------------------------------------------   0            /usr/lib/jvm/java-eleven-openjdk-amd64/bin/java   1111      auto mode   1            /usr/lib/jvm/java-11-openjdk-amd64/bin/coffee   1111      transmission manner * 2            /usr/lib/jvm/java-eleven-oracle/bin/java          1091      manual mode  Press <enter> to keep the electric current pick[*], or type selection number:                  

In this instance the installation paths are as follows:

1. OpenJDK xi is located at /usr/lib/jvm/java-11-openjdk-amd64/bin/java.
2. Oracle Java is located at /usr/lib/jvm/coffee-11-oracle/jre/bin/java.

Copy the path from your preferred installation. So open up /etc/surroundings using nano or your favorite text editor:

                      
              
                sudo                nano                /etc/surround              
            
                  

At the end of this file, add the following line, making certain to supplant the highlighted path with your ain copied path, simply do not include the bin/ portion of the path:

/etc/environs

          JAVA_HOME="/usr/lib/jvm/coffee-11-openjdk-amd64"                  

Modifying this file will ready the JAVA_HOME path for all users on your system.

Save the file and exit the editor.

Now reload this file to apply the changes to your electric current session:

                      
              
                source                /etc/environment              
            
                  

Verify that the environment variable is set:

                      
              
                repeat                $JAVA_HOME              
            
                  

Y'all'll meet the path you just ready:

                      
Output
            /usr/lib/jvm/coffee-xi-openjdk-amd64                  

Other users will need to execute the command source /etc/environment or log out and log back in to apply this setting.

Decision

In this tutorial you installed multiple versions of Java and learned how to manage them. You can now install software which runs on Java, such equally Tomcat, Jetty, Glassfish, Cassandra or Jenkins.

Source: https://www.digitalocean.com/community/tutorials/how-to-install-java-with-apt-on-ubuntu-18-04

Posted by: stahlevisiou.blogspot.com

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