摘要：

In this article, we will learn how to install Java 8 on Ubuntu OS. We will install JDK in Ubuntu. Java is a programming technology which is actually developed by Sun Microsystems. Java is free to download and use for commercial use.

Install Java 8 on Ubuntu
How to Install Java 8 on Ubuntu?

i) At first, we will download the package file from the official website.

http://www.oracle.com/technet... The download package is different for 64 bit and 32-bit versions.

ii) We will need some superuser privileges to install JDK. So we will use the following command-
sudo su

iii) The /opt directory is actually reserved for all the software and add-on packages. This software is not part of the default installation. The command for creating the directory for JDK installation is-

mkdir /opt/jdk

Creating a directory for JDK installation

iv) Then we will extract java into the /opt/jdk directory:

tar -zxf jdk-8u5-linux-x64.tar.gz -C /opt/jdk

Extract java into the /opt/jdk directory

v) Then we use the following command. This command verifies the file extraction into the /opt/jdk directory.

ls /opt/jdk

Verifies the file extraction into the /opt/jdk directory

vi) By default, we can find java executable in /opt/jdk/jdk1.8.0_05/bin/java directory. To set it as the default JVM we will use:

update-alternatives --install /usr/bin/java java /opt/jdk/jdk1.8.0_05/bin/java 100
update-alternatives --install /usr/bin/javac javac /opt/jdk/jdk1.8.0_05/bin/javac 100

Set the default JVM

Set the default JVM

vii) Then verify the java has been successfully configured. Run the following command-

update-alternatives --display java
update-alternatives --display javac

Verify the java has been successfully configured

Verify the java has been successfully configured

We can check installation by-

java -version

Check installation by java -version

viii) We can also update Java. Hence, download an updated version of Oracle’s website and extract to the /opt/jdk directory. After that, set it as the default JVM with a higher priority number:

update-alternatives --install /usr/bin/java java /opt/jdk/jdk.new.version/bin/java 110
update-alternatives --install /usr/bin/javac javac /opt/jdk/jdk.new.version/bin/javac 110