A newer version of Java 8 exists on this computer

Question

While trying to install Java 8 I am getting the message:

A Newer Version of this Product Already Exists

A newer build of this version of Java already exists on your system. It is not possible to install an older build. Click OK to exit this installation.

Two questions:

1) Since when it became impossible to have several versions of JDK on a computer?

2) Where could I take newer Java than the newest?

My Java folder is follows:

 Directory of C:\Program Files\Java

19.12.2013  20:39    <DIR>          .
19.12.2013  20:39    <DIR>          ..
27.01.2012  23:16    <DIR>          jdk1.6.0_20
08.09.2011  16:25    <DIR>          jdk1.6.0_27
05.09.2011  13:51    <DIR>          jdk1.7.0
27.04.2013  00:31    <DIR>          jdk1.7.0_21
04.10.2013  01:33    <DIR>          jdk1.7.0_40
19.12.2013  20:41    <DIR>          jdk1.7.0_45
08.09.2011  16:21    <DIR>          jre6
19.12.2013  20:41    <DIR>          jre7
21.11.2013  00:41    <DIR>          jre8

Answer 1

I manage to avoid this message and install JDK by deleting the following Registry entry:

HKLM\\SOFTWARE\\JavaSoft

After that JDK installer will ask you if you would like to reinstall it.

Answer 2

Steps to correct this problem:

Temporarily remove the values to the jdk in these environment variables:

JAVA_HOME (full removal), CLASSPATH (partial removal), PATH (partial removal)

Reset them to the correct version.

If you are going backwards to an earlier version, update "CurrentVersion" so it matches the subfolder in the "Java Development Kit" list.