After JDK is installed in Ubuntu, eclipse cannot be started.

Eclipse startup error: a Java Runtime Environment (JRE) or Java Development Kit (JDK) must be available in order to run eclipse. No Java virtual machine was found after searching
Following locations :...

This problem occurs when I installed two versions of eclipse on ubuntu1004: galieo + Helios. After I uninstalled the former, I found that eclipse cannot be started. If I found it online, I can solve it as follows:

Eclipse 3.6 has a strange phenomenon in Ubuntu 10.04. I have not passed the test and cannot determine whether it is caused by Ubuntu 10.04, JDK, or eclipse. This phenomenon is:

You can start eclipse on the terminal, but double-click it, or use the starter to start eclipse as follows:

A Java Runtime Environment (JRE) or Java Development Kit (JDK) must be available in order to run eclipse. No Java virtual machine was found after searching the following locations :...

The solution is to enter your eclipse directory on the terminal and enter:
Mkdir JRE
CD JRE
Ln-s your JDK directory/Bin

Solve the problem!

Source: http://www.cnblogs.com/dartagnan/archive/2010/12/01/2003528.html