Install JDK and open jdk under Ubuntu

Default JDK Installation:

sudo apt-get update

sudo apt-get install default-jre

Oracle JDK Installation:

1. Set PPA

sudo add-apt-repository ppa:webupd8team/java

sudo apt-get update

2. Installing JDK 9

sudo apt-get install Oracle-java9-installer

OPENJDK 7 Installation:

sudo add-apt-repository ppa:openjdk-r/ppa

sudo apt-get update

sudo apt-get install openjdk-7-jdk

Switch between versions

Update-Alternatives -config java

Update-Alternatives --config javac

Install JDK and open jdk under Ubuntu