Note Since 22 April 2016 the packages for Vivid have been removed, alas. News item in packages.ubuntu.com: "Reflect xenial release, add yakkety, remove vivid". The workaround of this answer is clever but no longer applicable in the current situation. As of 6 Jan 2017 there's no backport for java 8 on trusty packages.ubuntu.com/trusty-backports/java yet. Please edit as changes apply.
See the answer from Android official site
https://source.android.com/source/initializing.html
There are no available supported OpenJDK 8 packages for Ubuntu 14.04. The Ubuntu 15.04 OpenJDK 8 packages have been used successfully with Ubuntu 14.04. Newer package versions (e.g. those for 15.10, 16.04) were found not to work on 14.04 using the instructions below.
Download the .deb packages for your architecture from http://packages.ubuntu.com/vivid/openjdk-8-jdk:
openjdk-8-jre-headless
openjdk-8-jre
openjdk-8-jdk
Remember, you may obtain the architecture for your machine with:
$ uname -m
x86_64 represents a 64-bit (amd64) Linux kernel architecture and i386/i486/i586/i686 represents 32-bit (i386) system.
Optionally, confirm the checksums of the downloaded files using the information found on http://packages.ubuntu.com/vivid/openjdk-8-jdk.
For example with the sha256sum tool:
$ sha256sum {package file}
Install the packages:
$ sudo apt-get update
Run dpkg for each of the .deb files you downloaded. It may produce errors due to missing dependencies:
$ sudo dpkg -i {downloaded.deb file}
To fix missing dependencies:
$ sudo apt-get -f install
ppa:saiarcot895/myppa
, has a version of openjdk-8 that works. shrug