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 point to the JDK  It is currently set to  C  Program Files Java jre6   But I have clearly set my JAVA HOME to be C  Program Files Java jdk1 6 0 14  Where is ANT getting this value

User · Answer

I was facing the same problem  making the executable property in the javac tag to be set to the location of javac exe resolved the problem for me  This resolved the problem   lt javac srcdir    srcDir   destdir    buildDir   fork  true  executable  C  Program Files Java jdk1 7 0 03 bin javac   gt

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FYI  I am using Windows 7 and had to restart Windows in order for the new JAVA HOME setting to take effect

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I faced this problem when building my project with Jenkins  First  it could not find ant bat  which was fixed by adding the path to ant bat to the system environment variable path  Then ant could not find the jdk directory  This was fixed by right-clicking on my computer  gt  properties  gt  advanced  gt  environment variables and creating a new environment variable called JAVA HOME and assigning it a value of C  Program Files Java jdk1 7 0 21  Don t create this environment variable in User Variables  Create it under System Variables only  In both cases  I had to restart the system

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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 gt  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   gt 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   gt 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

User · Answer

When you say you have  clearly set  JAVA HOME to  C  Program Files Java jdk1 6 0 14  - is that what you see when you run  set  from the command line  I believe Ant will guess at a value for JAVA HOME if one isn t set at all    is it possible that you ve set JAVAHOME instead of JAVA HOME   If it s nothing like that  I suggest you edit the ant bat batch file  and whatever it calls - I can t remember whether it s convoluted or not offhand  to print out JAVA HOME at the start and at various other interesting places

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In Eclipse click Run  rarr  External Tools  rarr  External Tools Configurations  Click the JRE tab  Click the Installed JREs    button  Click the Add button   Select Standard VM  where applicable   Click the Directory button  Browse to your JDK version  not JRE  of your installed Java  e g  C  Program Files Java jdk1 7 0 04   Click Finish and OK  Select the JDK at Separate JRE and click Close  Re-run your Ant script     have fun    This worked in a particular scenario I encountered

User · Answer

Just set the JDK path from the below steps    Go to  Run  - External Tools -  External Tools Configuration -  Select  JRE  Then from the DropDown list select the available JDK   ex  jdk1 8 0 25

User · Answer

The semicolon was throwing me off  I had JAVA HOME set to  C  jdk1 6 0 26   instead of  C  jdk1 6 0 26   I removed the trailing semicolon after following Jon Skeet s suggestion to examine the ant bat file  This is part of that file   if   JAVA HOME         goto noJavaHome if not exist   JAVA HOME  bin java exe  goto noJavaHome   So the semi-colon wasn t being trimmed off the end  causing this to fail to find the file  therefore defaulting to  C  Java jre6  or something like that   The confusing part is that the HowtoBuild page states to use the semi-colon  but that seems to break it

User · Answer

If you have JAVA HOME set but there s a typo in it  you will also see the bogus reference to a jre6 path

User · Answer

To solve this problem add tools jar file in window- preferences- ant-  runtime

User · Answer

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

User · Answer

When everything else is correct try the following   Goto Window -  Preferences -  Ant -  Runtime -  ClassPath Expand Global Entries and check jdk tools available here  Add the required tools jar from a specific version of java such as  C  Program Files Java jdk1 6 0 45 lib tools jar   Now build and check the results    Note  Add tools jar for the java compiler that you want to use and give preference to it by moving it up in the list of tools jar when multiple tools jar  java compilers  are present

User · Answer

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

User · Answer

If need to run ant in eclipse with inbuilt eclipse jdk add the below line in build xml   lt property name  build compiler  value  org eclipse jdt core JDTCompilerAdapter   gt

User · Answer

In eclipse set the installed JRE setting to the JDK - in the project  project properties -  Java Build Path-  Libraries   or global default in preferences  Java- Installed JREs   The eclispe setting is stronger than the system variable

User · Answer

I have met the similiar issue  I would link to run Ant task fron Maven build and I got the issue  I have fixed it as bellow steps    Make sure JAVA HOME is set right  You can check it on Windowns in command line as   C  echo  JAVA HOME  Result would look like  C  Progra 1 Java jdk1 6 0 30  Copy file tools jar from  JAVA HOME  lib to lib directory of Maven    And it worked for me

User · Answer

Quick work around for the same is  Copy C  Program Files Java jdk1 6 0 14 lib tools jar to C  Program Files Java jre6 lib   This exception is coming because JAVA HOME is being set as C  Program Files Java jre6 and Ant is not able to find tools jar in it

User · Answer

I had the same problem   My JDK package pointed by JAVA HOME didn t have any tools jar Be sure that your JDK instal lation  has tools jar    clearly the message error is confusing

User · Answer

Make sure you do not use the trailing semicolon  This will not work    set JAVA HOME C  Program Files  x86  Java jdk1 6 0 29    This will   set JAVA HOME C  Program Files  x86  Java jdk1 6 0 29

User · Answer

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

User · Answer

I hope you are aware about System and User environmental variables  The user ones are preferred over system  If you have set your JAVA HOME in system variables and if there is an entry for the same in user variables  then you will get the latter one only    Right click on My computer  Go to properties  Select Advanced tab and click on Environmental variables to see the list of user and system environment variables

User · Answer

I encountered the same problem when I try to run Ant build using the following command   java -cp ant jar ant-launcher jar org apache tools ant Main   The output of the command is   BUILD FAILED XXX build xml 8  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   usr lib jvm java-6-openjdk jre    It seems the java executable is picking   usr lib jvm java-6-openjdk jre  as JAVA HOME  as opposed to   usr lib jvm java-6-openjdk  where JDK is installed   I resolved this issue by setting fork  yes  in my  lt javac gt  task   Take a look at  http   ant apache org manual Tasks javac html

User · Answer

had the same problem   c  jb src build xml 191  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   Total time  0 seconds  c  jb src gt echo  JAVA HOME  c  Program Files Java jdk1 7 0 13   solution   path   c  ant bin   PATH  path   c  Program Files Java jdk1 7 0 17 bin  PATH  set  JAVA HOME c  Program Files Java jdk1 7 0 13    I guess the jdk path instruction alone would do it but I m to lazy to figure it out above solution is bullet proof   -   Also using Windows7

User · Answer

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

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

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