Few months ago, I wrote a blog post on Installing Oracle JDK 7 (Java Development Kit) on Ubuntu. It has several steps to install the JDK on Ubuntu.
Every time when there is a new version, I upgrade the Java version in my laptop. Since I do few repetitive steps for every Java installation, I wrote a simple installation script for Java.
The installation script is available at GitHub: https://github.com/chrishantha/install-java
You just have to run "install-java.sh" with root privileges once you download the JDK from Oracle. It also supports the installation of JDK Demos and "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files"
Please refer the install-java.sh README at GitHub.
The script supports JDK 7 and JDK 8. Please try the installation scripts and let me know any feedback! :)