interesting.... i thought you could pick your jre? i guess it is just the compile sdk?

You can pick the JRE/SDK when Eclipse starts with the -vm argument but not while it's running for Ant. Well, starting in Eclipse 3.0 M1 you can apparently -- I haven't tried it yet.

Google picked up the post. If you build it, they will come. :)

http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=eclipse+com.sun.tools.javac.Main+is+not+on+the+classpath

i did a search on google for this about 10 minutes ago. internet time is a trip.

anyway, i went ahead and kept using netbeans 'cos of this--glad that you hit us up with this info! i got other issues, but i'm past this one at least. word.

j.

This came in handy. Thanks! I don't know how long it would have taken me to try changing the VM that Eclipse itself is running in. Since it doesn't look like a Java (Swing) app, I might have never thought of it.

Thanks for that post. Saved me quite some headache... I had to set some tricky quotes though because I got a space in my jdk-path:

"C:\Program Files\eclipse\eclipse.exe" -vm "C:\Program Files\j2se1.4.1_03\bin\javaw.exe"

Thanks for the post, it is really clear and helpful.

Best regards.

Thanks Ryan, you just saved me a ton of time. Very much appreciated.

Thanks a lot for your hint. I found it via google and it saved me a lot of time.

Hey, I've done this...to no avail. I even wiped out and uninstalled all the other JDKs and JREs I had and
am only using one. Any other thoughts?

can't you just add "tools.jar" from the jdk to the preferences/ant/classpath? That's what I did and it solved the problem.

BEAUTIFUL...DUH, so much for being an eclipse newbie.
Adding the tools.jar worked! You da (man?)!

angry planet: Sure, you could do that. I wanted a solution that didn't involve changing Eclipse's Ant preferences so that it would work with an out-of-the-box version of Eclipse.

The lower the number of those types of project tweaks I have to do after a fresh CVS grab to get the project to *just work*, the better (we don't check in Eclipse preferences to CVS).

Thanks,
I was searching a long time to find a solution for the ant / eclipse bug.

Now it works :-))

Thanks a bunch - I've wasted weeks on this bug

Thanks a bunch. Another geek saved by your post.

Thanks a lot. I couldn´t figure out how to solve this problem, until i found your post. Great work.

Worked like a charm. Thanks!

I tried with the -vm option -> didn't help...
But with the tools.jar in the ant Runtime classpath it worked....

Uff, thanks a lot...

Hit this bug. Tried adding JAVA_HOME to the ant.bat file, the ant preferences, the java classpath environment, my windows environment variables -- all to no avail.

But doing a search on "eclipse ant bug" pulled this up as the 2nd item, and putting in -vm worked like a charm!

Thanks!

Just another thanks for the list. Luckily checked for the post after the first painful hour!!

Cheers

Rock on! Thanks much for the info.

Thanks a lot for the post... you were the first result brought to me by google! :)

This was sweet. Thanks for the tip.

Excellent. Saved me a lot of time.
Let us know when the Eclipse guys releases the patch.

Thanks, I was looking the whole day for the reason of this problem.

wwwwiiiicccckkkkkkeeeedddddddd

Ryan you are a star. After three hours of head bashing. 11/10

Thanks a lot for the help

I thought IDEs were supposed to save you time! Have probably spent days on this. I had assumed it was something I was doing wrong, being an Eclipse Newbie, not some strange "bug". Thanks to google. I also had to add tools.jar. This is the second bewildering problem I have had with Eclipse that sucked up a lot of time tracking it down.

Thanks man i got it

i will be in touch with you for future problems

this came in v. helpful -- thanks!

Very usefull!!! Thanks ;-)

Thanks a lot Ryan!

Thanks so much for this!!! Really made a difference in my work. I've been figuring this out for 2 days... saved me some more grief. :)

thanks!

Thank you, thank you, thank you.

property name="build.compiler" value="org.eclipse.jdt.core.JDTCompilerAdapter"

on your ant script ..

helps !

Thanks mate, great work.

Muchas gracias por tu ayuda. That error was annoying me.

External tools ->ANt Build -> Main tab:

In Arguments put:

-Dbuild.compiler=org.eclipse.jdt.core.JDTCompilerAdapter

In build.xml leave

Thanks a lot - have been stuck with this for a couple of days, google search gave me this blog. My peace of mind is restored.

or...

As kimsk112 suggested on the java forum at sun.

"With the eclipse version 2.1.1, I solve it by adding tools.jar (in JAVA_HOME\lib) into the runtime classpath of ANT (windows->preferences->ant->Runtime->add jars."

http://forum.java.sun.com/thread.jsp?thread=440539&forum=31&message=1996353

Thanks, man!

with websphere application developer (wsad 5.1) those hints did not work for me. wsad works on ibm jdk 1.3 and so compiling for jdk 1.4 seems to be hard for ant. i found another wicked solution:
1) remove tools.jar from your ant classpath
2) remove your JDTCompilerAdapter from your build.xml
3) add the following attributes to the statement:
a) fork="yes"
b) compiler="javac1.4"
c) source="1.4"
it sounds silly and ant tells something about ignoring the compiler statement but: only with all three attributes i can build jdk 1.4 projects without any change on my wsad 5.1!
(better solutions welcome.)
cheers,
jörn

U saved my life

Thanks, tricky!

I think Iqbal got it right! Worked for me and should work with no changes to the ant build.xml. Changing the build.xml could work ( haven't tried!)but this is an IDE specific change and may not be required in the project team members don't use the Eclipse IDE.

Thanks, just saved by your blog, and specially by the suggestion to add the tools.jar to Ant classpath !

Thanks for your blog :)

I installed the lastest build of Oracle and it hijacked my 'Path'settings.

AWESOME! THANKS FOR THE TIP!!!!

Tools.jar worked perfectly!
Thanks for the tip!!

Ryan, thanks for your post about eclipse/ant and the way eclipse uses the first jvm it finds. I wasted a lot of time trying to figure out what the problem was on my machine. However, google has indexed your page, thanks a bunch.

Regards,
kash

Thanks for the tip, its always great to feel not alone in adversity;).

I'm curious:

"You can pick the JRE/SDK when Eclipse starts with the -vm argument but not while it's running for Ant. Well, starting in Eclipse 3.0 M1 you can apparently -- I haven't tried it yet."

Where did you source this information?

I am running Eclipse3.0 M5, (as of 3 hours ago, yes a newbie!), and I'm wondering where I could find out how to do this...

Paul MG: I found that information in the plan for Eclipse 3.0 on the Eclipse web site. Now that the 3.0 stream is settling down (at M5 like you said, and I believe after M6 they are starting RCs) I'll go back and figure out how to do this. Apparently it's been cleaned up quite nicely. I'll post the results on my blog and link to it from here.

You've already come a long way in 3 hours. :) Have fun with Eclipse!

The ant/classpath worked great... Thanks for that and keep posting such good stuff for us google users...
Sudhindra

thanks mate. great help from your shameless bugification.

I have a similar problem, not with Ant but with a JSP application. None of these hints worked out so far.

I use Eclipse 2.11, Tomcat 4.1 and the Lomboz plugin 2.12. When I run the deployed application, everything works fine. But when running from Eclipse, everytime I encounter an uncompiled JSP page, I get that #@&! error again:
Unable to find a javac compiler;
com.sun.tools.javac.Main is not on the classpath.
Perhaps JAVA_HOME does not point to the JDK

Any suggestions appreciated ;o)

The commandline fix worked for me on WSAD 5.1.0 build id 20030726_2016 with IBM's 1.3.1 JDK. Thanks.

Just as a suggestion, you can use -vm "%JAVA_HOME%\bin\javaw.exe" (on windows, modify as appropriate for other platforms) and then have any further changes to the JAVA_HOME reflected in the default Eclipse/WSAD environment.

Thank you for posting this. I was starting to get frustrated...

Man, Saved me a lot of time :-) Changing the VM + adding tools.jar worked

Thanks a lot! Just saved a lot of time and my life... :)
Greetings from Germany

nine months later, this post is still helping folks... like me...

Thanks!

--Josh

Instead of changing the JVM used in eclipse, I only added the correctly JDK path to Ant's runtime classpath. I don't know if this is fixed in my eclipse version, version 2.12 build 200311030802, so this may or may not work on your eclipse.
Choose "Windows->Preferences->Ant->Runtime", select the first tab "Classpath", and then use "Add JARs..." to add "YourSDKPath\lib\tools.jar". In my computer, that is "D:\j2se\lib\tools.jar".
Hope it may help also.

Just wanted to add my thanks to that of everyone else. This is exactly the kind of tip I've learned to love blogs for.

Ryan, you rock!
Helped solve what could have been a hair-puller!

Still helping out, 11 months later. The problem only cost me a couple of hours, but hopfully Eclipse 3.0 will have fewer of these "features".   ;-)

Hi,

I have installed Eclipse3.0M8 with jre1.4.
My project however, needs to be compiled with jdk1.3, and when I use ANT I specify to use jre1.3.1_09, however it still points the java home
to java1.4 and I get the following error when I run my target -the major.minor version '48.0' is too recent for this tool to understand.

I have tried the above changes (by adding eclipse_dir) as an environment variable, but no such luck
Any ideas?

thanks,

Gypsy`s tip worked for me. Thanks a lot. Greetings from Brasil.

Thanks a million. I was beating my head against the wall for HOURS! You rock :)

Hey, thanks a lot! This issue is still (oct 2004) an active problem. Great solution, now I can finally continue with the really important stuff! :)

Hey, thanks a lot! Solved the problem I've been working on for the last 2 hours!

If you're only going to use one JDK, you can just set a system variable.

Under Windows, open the "System" Control Panel, click the advanced tab, click on the "Environment variables" button at the bottom, and make sure you have a System variable called JAVA_HOME pointing to the JDK root (e.g. c:\progs\java\j2sdk1.4.2_05).

That's really all you need to do in most cases.

Fantastic. It works.

Thanks man, I was beating my head against a wall over this one.

Great stuff - I'm using WSAD 5.1.2 and was getting all kinds of strange classnotfound errors for SAX and such. Adding the -vm switch stopped them.

yes.. worked. good shot :)

You can also change that by going Windows | Preferences | Java. Then you can managed the JVM's. You must search for the java executable.

FOR ECLIPSE 3.1   (maybe 3.0):
Set your preferred JRE or JDK using:   "Window" menu -> "Preferences" -> "Java" -> "Installed JREs".
In my case only a JRE was listed.   I used "Add..." for my JDK.
Then be sure the correct one is checked!   Click "OK" and be happy.   Thanks for the google-pad, Ryan!

Following the hints of Mike Cepek above I realised that Eclipse somehow had forgot about all installed SDKs. Very weird...
I was lazy so I used search instead and then just selected the latest SDK.