Why does ANT tell me that JAVA_HOME is wrong when it is not?

Question

I get the error:

C:\\dev\\ws\\springapp\\build.xml:81: Unable to find a javac compiler; com.sun.tools.javac.Main is not on the classpath. Perhaps JAVA_HOME does not

Answer 1

Actually found this answer on superuser.com, but I had to copy tools.jar from my JDK\lib directory to the JRE\lib directory.

Makes ZERO sense...only thing I can think of is Sun introduced this bug in the latest Java runtime (Java 7 Update 11) or a bug in Ant in how it reads the current JDK location (the JRE is more updated than the JDK obviously which is also stupid of Sun...they should release the JDK each time they update the JRE).

My JAVA_HOME was set correctly. I confirmed by doing "set JAVA_HOME". It pointed to my JDK directory and was spelled correctly. However, Ant was claiming it couldn't find javac, but thought JAVA_HOME was in my JRE directory.

My system worked fine before the latest Sun JRE7 updates (10 and 11). Ant is version 1.8.4

Answer 2

It's also possible that you have included /bin in your JAVA_HOME setting, and Ant is adding /bin to it - thereby not finding any exe's. It's happened to me :}

Answer 3

It is common to get this issue. I cannot set any specific Java home in my system as I have 2 different version of Java (Java 6 and Java 7) for different environment. To resolve the issue, I included the JDK path in the run configuration when opening the build.xml file. This way, 2 different build files use 2 different Java version for build. I think there might be a better solution to this problem but at least the above approach avoid setting the JAVA_HOME variable.

Answer 4

Set JAVA_HOME in the environment variables as D:\Program Files\IBM\SDP\jdk Do not give any quotes or semicolon. It's works for me.Please try the solution. Actually in ant.bat it checks for appropriate JAVA_HOME in case if ant.bat not able to find it then it's JAVA_HOME points the default JRE.

Answer 5

I was also facing the same problem. I am using Windows 7 and I had two versions of java installed. First I have installed latest version java 7 and then version 5.

Contents of my java installation directory:

C:\Program Files\Java>
jdk1.5.0_14
jdk1.7.0_17
jre1.5.0_14
jre7

and my JAVA_HOME was set to the correct value, which was:

C:\>set ja
JAVA_HOME=C:\Program Files\Java\jdk1.5.0_14

But still I was getting the same problem:

XXXXXXX\build.xml:478: The following error occurred while
executing this line:
XXXXXXX\build.xml:477: 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.
It is currently set to "C:\Program Files\Java\jre7"

After trying out all the suggestion in this thread I realized my mistake. I was trying to set the environment variable in "User variables" instead of "System Variables" section. After setting it in "System Variables" it worked fine. I am facing another problem though.

The default version of java it points to is still 7.

C:\>java -version
java version "1.7.0_17"
Java(TM) SE Runtime Environment (build 1.7.0_17-b02)
Java HotSpot(TM) Client VM (build 23.7-b01, mixed mode, sharing)

I am not sure how to make it point to version 5.

Answer 6

FYI, I am using Windows 7 and had to restart Windows in order for the new JAVA_HOME setting to take effect.