Oracle has started auto-updating Java runtime JRE 7 to JRE 8. Auto-update was turned on January 20, 2015 and affects Windows 32-bit and OS X users who use Java's auto-update mechanism. This is not a silent upgrade and requires user permission. JRE 8 was released on March 2014 and has been the default version on Java.com since October 2014.
On the Windows operating system, only the latest JRE will be replaced; other JRE versions will be not be removed. However OS X users will only have JRE 8 available in the web browser after the upgrade. (OS X users can still have multiple JRE versions available for desktop applications.) In enterprises where the IT department manages Java setup and versions, auto-update will not affect users. Computers not running Windows 32-bit or OS X will also not be automatically updated, and will need to be manually upgraded. Note that the Java auto-update for Windows 64-bit has now been implemented in Java 8 Update 20. More information about Java auto-update can be found in the What is Java Auto Update? page from Java.com.
A frequently asked question is whether existing Java programs will continue to work after the update. Oracle strives to make new versions of Java backward compatible and thus the vast majority of Java applications will work without any changes, i.e., they are binary compatible. Of course, there are always exceptions/edge cases. If you have a third-party application that is not yet certified with Java 8 and requires Java 7, please contact the application provider directly. For all the technical details, Oracle has a Compatibility Guide for JDK 8 discussing binary, source and runtime compatibilities, JRE and JDK incompatibilities, removed features and deprecated APIs.
Java 7 was first released in July 2011. Oracle will stop posting public updates of Java 7 after April 2015. This is consistent with their stated Java policy, which is to end public updates three years after the general availability date of the major release, one year after the GA of a subsequent major release, and six months after a subsequent major release has been established as the default JRE on Java.com.
Existing Java 7 downloads will remain accessible in the Java Archive on the Oracle Technology Network. For users who wish to continue receiving security updates for Java 7, a support contract with Oracle or a license for Java SE advanced products is required. Continued use of Java 7 without security updates is not recommended.
Java 8's highlighting feature is the implementation of lambda expressions. It also includes a new Date and Time API and a new JavaScript engine called Nashhorn. The complete feature list can be found in the official What's New in JDK 8.
