How to install the JDK on Ubuntu Linux

Note: This is an old question and the answers reflect the world as it was then. Modern Ubuntu distributions have OpenJDK available which can be installed with sudo apt install default-jdk --- I am trying to install the [Java Development Kit][1] (JDK) on [Ubuntu][2] Linux distribution, but I am unable to install it. What are the steps to install it on Ubuntu? [1]: https://en.wikipedia.org/wiki/Java_Development_Kit [2]: https://en.wikipedia.org/wiki/Ubuntu_%28operating_system%29