changing jdk in eclipse - eclipse

Question

I am trying to update my eclipse to work with a jdk and not a jre.
I followed the instruction in this forum , also search google for answers but for some reason it still don't work.
I try'ed going to preferences ->java->install jre's , removing the old jre from there and using the path for the jdk.
also try'ed going to project properties -> java build path -> jre system libraries -> edit-> workspace default jre.it also says there i'm using jdk.
I even try'ed adding to the ini file the next path C:\Program Files\Java\jdk1.6.0_31\bin\javaw.exe
but when i try'ed deploying my program to app engine i get the next message :
Unable to update app: Cannot get the System Java Compiler. Please use a JDK, not a JRE.
my eclipse version is juno 4.2 and my jdk version is 1.6.0_31
I don't know what else i need to change. I even uninstall my older jre from my computer but eclipse still don't work with the jdk ( although it recognize it )
I'm out of idea's ... anyone could help me please ??
this is my ini file :
-startup
plugins/org.eclipse.equinox.launcher_1.3.0.v20120522-1813.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.1.200.v20120522-1813
-product
org.eclipse.epp.package.jee.product
--launcher.defaultAction
openFile
--launcher.XXMaxPermSize
256M
-showsplash
org.eclipse.platform
--launcher.XXMaxPermSize
256m
--launcher.defaultAction
openFile
-vmargs
-Dosgi.requiredJavaVersion=1.5
-Dhelp.lucene.tokenizer=standard
-Xms40m
-Xmx512m
-vm
C:\Program Files\Java\jdk1.6.0_31\bin
thanks for the help

Answer 1

If you want to change JVM Eclipse itself should run on, the right place for that is eclipse.ini. Here are instructions on how to specify that: eclipse.ini.
Common mistakes are specifying -vm parameter name and the value in one line, or missing '-vm', or misplacing it. Also, pay attention to -vm format on different OSes.
EDIT (after .ini file published): your -vm option comes after -vmargs, which is wrong (both lines are treated as VM args). The correct parameter placement in your .ini file would look like this:
...
--launcher.XXMaxPermSize
256m
--launcher.defaultAction
openFile
-vm
C:\Program Files\Java\jdk1.6.0_31\bin
-vmargs
-Dosgi.requiredJavaVersion=1.5
-Dhelp.lucene.tokenizer=standard
-Xms40m
-Xmx512m

Answer 2

Below you can find my eclipse ini where I set a dedicated JDK via
-vm C:/Program Files (x86)/Java/jdk1.7.0_10/bin/javaw.exe
Have a look at the section "Specifiying the Java Virtual Machine" in the eclipse help.
Quote:
Tip: It's generally a good idea to explicitly specify which Java VM to use when running Eclipse. This is achieved with the "-vm" command line argument as illustrated above. If you don't use "-vm", Eclipse will look on the O/S path. When you install other Java-based products, they may change your path and could result in a different Java VM being used when you next launch Eclipse.
-startup
plugins/org.eclipse.equinox.launcher_1.3.0.v20120522-1813.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.1.200.v20120522-1813
-vm
C:/Program Files (x86)/Java/jdk1.7.0_10/bin/javaw.exe
-showsplash
org.eclipse.platform
--launcher.XXMaxPermSize
256m
--launcher.defaultAction
openFile
-product
org.eclipse.epp.package.jee.product
--launcher.defaultAction
openFile
--launcher.XXMaxPermSize
256M
-vmargs
-Dorg.eclipse.ecf.provider.filetransfer.httpclient.retrieve.readTimeout=999999
-Dosgi.requiredJavaVersion=1.5
-Dhelp.lucene.tokenizer=standard
-Xms128m
-Xmx1024m

Answer 3

None of the other answers worked for me. I eventually just removed the "jre7" directory and, presto-chango, Eclipse started using the JDK that was installed next to it.