Install jdk on Ubuntu

This passage is from :http://ubuntuhandbook.org/index.php/2014/02/install-oracle-java-6-7-or-8-ubuntu-14-04/

This simple tutorial is going to show you how to easily install Oracle Java (JDK) 6, 7, or 8 in Ubuntu 14.04 Trusty Tahr via PPA.

There’s a Launchpad PPA (Personal Package Archive) maintained by webupd8.org, a popular Ubuntu Linux blog, which provides the most recent installers to automatically download and install Oracle Java JDK6 / JDK7 / JDK8 from
oracle website. Note there are no actual Java files in this PPA.

To get started:

Press Ctrl+Alt+T on your keyboard to open a terminal window. When it opens, copy and paste the command below and hit enter. Input your user password when prompts and it will add the PPA repository into your system.

sudo add-apt-repository ppa:webupd8team/java

After that, update package lists via:

sudo apt-get update

To install Oracle Java 8, run:

sudo apt-get install oracle-java8-installer

Change the number 8 to 6 (or 7) in the code to install Java 6 (or 7).

While installation, you’ll be asked to agree the license and then the installer start downloading Java file from oracle website and install it on your system.

To set the default Java, run:

sudo apt-get install oracle-java8-set-default

Also change number 8 to the Java version you want.

Finally check whether everyting is OK:

java -version

It will output something like below:

java version “1.7.0_60″

Java(TM) SE Runtime Environment (build 1.7.0_60-b19)

Java HotSpot(TM) 64-Bit Server VM (build 24.60-b09, mixed mode)