How to install Java on Ubuntu 18.04

Install Java on Ubuntu 18.04

Java is the popular programming language owned by Oracle. Java is used to build cross-platform applications. Over 3 billion devices run on Java. In this tutorial, we are going to install Java on Ubuntu using different methods.

Java has following three editions:

1. Standard Edition(SE).
2. Micro Edition(ME).
3. Enterprize Edition(EE).

Following two implementations available for Java:

1. Oracle Java.
2. OpenJDK Java.

In this tutorial we are going to install Standard Edition (SE). There is no more difference in Oracle Java and OpenJDK Java as Oracle Java provides some additional enterprise features.

Prerequisites

Before you start to install Java on Ubuntu 18.04. You must have the non-root user account on your system with sudo privileges.

1. Install Default OpenJDK

Currentally, OpenJDK 10 is the default version for Ubuntu 18.04. To install OpenJDK 10 run following commands.

Update the package manager index typing following command.

sudo apt update

Enter the following command to install Default OpenJDK on Ubuntu 18.04.

sudo apt install default-jdk

Confirm the installation and check the version typing following command.

java -version

Output should be:

openjdk version "10.0.1" 2018-05-29
OpenJDK Runtime Environment (build 10.0.1+10-Ubuntu-3ubuntu1)
OpenJDK 64-Bit Server VM (build 10.0.1+10-Ubuntu-3ubuntu1, mixed mode)

2. Install OpenJDK 8, 10, or 11

You can install the specific version of OpenJDK by using the following command. Replacing [VERSION_NUMBER] with the version number you want to install.

sudo apt install openjdk-[VERSION_NUMBER]-jdk

For example, if you want to install OpenJDK 8 which is the current LTS version of OpenJDK then just run following command.

sudo apt install openjdk-8-jdk

3. Install Oracle Java With apt

Oracle Java which is the official version from Oracle can be installed from webupd8team repository. You will need to add webupd8team repository to sources list running following command.

sudo add-apt-repository ppa:webupd8team/java

Now update the package manager index and install Oracle with the following command.

sudo apt update && sudo apt-get install oracle-java8-installer

You will be prompted to accept license terms select YES to continue.

After accepting license it will download Oracle JDK and install it on your system.

4. Install Java From Oracle Website

As web8team repository only contains Java 8. If you want to install Java 10 then download the package from Oracle Official Website. Here we are going to install Java 10 while you can choose another version.

Download Oracle Java 10 using the following command.

curl -L -b "oraclelicense=a" -O http://download.oracle.com/otn-pub/java/jdk/10.0.2+13/19aef61b38124481863b1413dce1855f/jdk-10.0.2_linux-x64_bin.tar.gz

Create a new directory for java installation.

sudo mkdir /usr/local/oracle-java-10

Now extract downloaded Java file inside the recently created directory.

sudo tar -zxf jdk-10.0.2_linux-x64_bin.tar.gz -C /usr/local/oracle-java-10

Now run following command to create alternatives. Which will create symbolic links for default commands.

sudo update-alternatives --install "/usr/bin/java" "java" "/usr/local/oracle-java-10/jdk-10.0.2/bin/java" 1500

sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/local/oracle-java-10/jdk-10.0.2/bin/javac" 1500

sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/local/oracle-java-10/jdk-10.0.2/bin/javaws" 1500

5. Setting up default Java Version

If you have installed multiple versions of Java on your system then you can change the default version running following command.

Check Current Java Version running following command.

java -version

Now to change default Java version run following command.

sudo update-alternatives --config java

The output should be:

There is 1 choice for the alternative java (providing /usr/bin/java).

  Selection    Path                                           Priority   Status
---------------------------------------------------------------------------------------
  0            /usr/lib/jvm/java-8-oracle/jre/bin/java          1081      auto mode
  1            /usr/lib/jvm/java-8-oracle/jre/bin/java          1081      manual mode
* 2            /usr/local/oracle-java-10/jdk-10.0.2/bin/java    1500      manual mode

Press  to keep the current choice[*], or type selection number:

NOTE: to change version just enter the number in the selection column

Another example:

6. Set the JAVA_HOME Environment Variable

To set JAVA_HOME environment variable run following command and copy the path you want to be set as JAVA_HOME.

sudo update-alternatives --config java

Run the following command to set JAVA_HOME variable.

sudo nano /etc/environment

Add the following line to the end of file

JAVA_HOME="THE PATH YOU HAVE COPIED"

Exit by using Ctrl+x then pressing y:

Apply the changes by running following command.

source /etc/environment

Now verify JAVA_HOME path typing:

echo $JAVA_HOME

Conclusion

You have successfully learned How to install Java on Ubuntu 18.04. If you have any queries regarding this then please don’t forget to comment below.