Ubuntu: OpenJDK 8 - Unable to locate package

Question

So I just installed Ubuntu, and this is my first time working in a Linux environment, so bear with my noobishness here.

Anyway, I downloaded the Java 8 JDK directly

Answer 1

As you can see I only have java 1.7 installed (on a Ubuntu 14.04 machine).

update-java-alternatives -l
java-1.7.0-openjdk-amd64 1071 /usr/lib/jvm/java-1.7.0-openjdk-amd64

To install Java 8, I did,

sudo add-apt-repository ppa:openjdk-r/ppa
sudo apt-get update
sudo apt-get install openjdk-8-jdk

Afterwards, now I have java 7 and 8,

update-java-alternatives -l
java-1.7.0-openjdk-amd64 1071 /usr/lib/jvm/java-1.7.0-openjdk-amd64
java-1.8.0-openjdk-amd64 1069 /usr/lib/jvm/java-1.8.0-openjdk-amd64

BONUS ADDED (how to switch between different versions)

• run the follwing command from the terminal:

sudo update-alternatives --config java

There are 2 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
------------------------------------------------------------
  0            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1071      auto mode
  1            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1071      manual mode
* 2            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1069      manual mode

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

As you can see I'm running open jdk 8. To switch to to jdk 7, press 1 and hit the Enter key. Do the same for javac as well with, sudo update-alternatives --config javac.

Check versions to confirm the change: java -version and javac -version.