Unable to locate tools.jar. Huh?!

I’m working on an update to a legacy build process that I want to move to ant.  When I got to my first test, “Does it do anything if I run it against a skeleton build.xml on this machine?”, I found my first error (warning, if you want to be pedantic).

D:\BuildNG>ant
Unable to locate tools.jar. Expected to find it in C:\Program Files\Java\jre6\lib\tools.jar
Buildfile: D:\BuildNG\build.xml

help:
     [echo] Common build targets:
     [echo] jar         - Builds testconsole.jar
     [echo] build       - Same as clean+jar
     [echo] compile     - Compiles TestConsole classes
     [echo] clean       - Remove all *.class and testconsole.jar

BUILD SUCCESSFUL
Total time: 0 seconds

In retrospect, the problem should have been clear to me. However, that would have only been the case had I read the entire error message rather than stopping at the first full stop and starting a search for tools.jar.

Searching through some threads over at stackoverflow.com, I came across many folks suggesting that it was an environment problem. Checking my JAVA_HOME variable seemed to confirm that at first.

D:\BuildNG>echo %JAVA_HOME%
%JAVA_HOME%

However, I still hadn't found a copy of tools.jar anywhere that I might have expected. At this point, I suddenly had one of those head-smacking, "what was I thinking?" insights. Usually, if I'm doing Java development, I'm doing it in a VM. I had never installed a JDK on the machine where I was testing the invocation! I installed the latest JDK and set JAVA_HOME. Problem solved, world saved.

The takeaway lesson is to always check the basic things.  “Do I actually have the JDK installed?” is about the same level of question as “Is it plugged in? Is it turned on?”  Sometimes, though, it’s exactly the question to ask.

Comments

[Maxim]

I have JRE and JDK installed. echo %JAVA_HOME% gives %Program Files%\Java\jdk1.6.0_26 which is correct, inside of it lib folder that contains tools.jar file. But "ant" stubbornly says "Unable to locate tools.jar. Expected to find it in C:\Program Files\Java\jre6\li
b\tools.jar". Do you have any ideas how to configure this?

[Rob Huffstedtler]

Maxim, what does your CLASSPATH look like? Actually, why don't you do a "set" so we can see all your environment variables.