Ext.: http://stackoverflow.com/questions/1736993/eclipse-mac-os-default-jre-missing
1) Follow Joshua ' s answer: "Help->install New software ... Select:galileo-http://download.eclipse.org/releases/galileo under programming Languages choose:eclipse Java Development Tools 3.5.x ... "
2) then go to Eclipse, Preferences, Java-installed JREs.
3) Click ADD.
4) under ' Installed JRE Types "You should see the previously missing" MacOS X VM ". Select this and click NEXT.
5) Click the BROWSE button next to the JRE home field, and the dialog box should say "Select the root directory of the JRE Installation "
6) Browse To/system/library/frameworks/javavm.framework/versions/1.5.0/home
7) Click OPEN.
8) in the JRE Name field type "JVM 1.5"
9) From there you should just is able to click FINISH and has your JRE available.
I used this to fix a missing JRE error building a Google App Engine project.
Eclipse-mac Os Default JRE missing