Ant is using wrong java version

Question

I m using Ant 1 7 0 and installed java 1 6 which is in JAVA HOME   I want to build a project using java 1 5  so I ve exported JAVA HOME to be my java 1 5 directory    java -version   says  1 5    When I run Ant it uses java 1 6

User · Answer

By default the Ant will considered the JRE as the workspace JRE version. You need to change according to your required version by following the below.

In Eclipse:

Right click on your build.xml click "Run As", click on "External Tool Configurations..." Select tab JRE.
Select the JRE you are using.
Re-run the task, it should be fine now.

User · Answer

Just had this issue  it happened because I d first added the build file to the ant-view when the default JRE was 1 6     There was no project-specific JRE and I changed the default to 1 5  even eclipse was running in 1 5  and JAVA HOME was 1 5 too   Running the ant target from the command line used JRE 1 5  but within eclipse it still used 1 6   I had to right-click the ant target  select Run As    and change the JRE under the JRE tab   This setting is remembered for subsequent runs

User · Answer

You can also specify in a javac task what level of compatibility   1 4  1 5  1 6   you want to use  you can set the  source  and  target  level values  check the docs here   Javac task documentation

User · Answer

If you are not using eclipse  Then you can change the ant java property directly on the file as mentioned here   http   pissedoff-techie blogspot in 2014 09 ant-picks-up-incorrect-java-version html

User · Answer

Build file    lt target name  print-version  gt       lt echo gt Java JVM version    ant java version  lt  echo gt       lt echo gt Java JVM detail version    java version  lt  echo gt    lt  target gt    Output    echo  Java JVM version  1 5  echo  Java JVM detail version  1 5 0 08

User · Answer

You could achieve that with following steps  if you are using Eclipse IDE    Right click on the task in your ant build file  build xml   Mouse over  Run As   click on  External Tool Configurations      Add followings to  Arguments    -Dant build javac target 1 5 -Dant build javac source 1 5

User · Answer

You can run the ant task echoproperties and look for  quot java version quot  or ant -v and look for  quot Java version quot   e g  on my machine ant echoproperties   grep java version  shows   echoproperties  java version 11 0 9 1  and ant -v   grep -i  quot java version quot   shows  Detected Java version  11 in   opt java zulu11 43 55-ca-jdk11 0 9 1-linux x64

User · Answer

In Eclipse    Right click on your build xml click  Run As   click on  External Tool Configurations     Select tab JRE   Select the JRE you are using    Re-run the task  it should be fine now

User · Answer

Run ant in verbose mode   ant -v and looks for clues

User · Answer

According to the Ant Documentation  set JAVACMD environment variable to complete path to java exe of the JRE version that you want to run Ant under

User · Answer

You can use the target and source properties on the javac tag to set a target runtime  The example below will compile any source code to target version 1 4 on any compiler that supports version 1 4 or later    lt javac compiler  classic  taskname  javac  includeAntRuntime  no  fork   deprecation  true  target  1 4  source  1 4  srcdir    src   destdir    classes   gt    Note  The  srcdir  and  destdir  are property values set else where in the build script  e g   lt property name  classes  value  c  classes    gt

User · Answer

If you run Ant from eclipse  the eclipse will use jdk or jre that is configured in the class-path build path

User · Answer

Use the following 2 properties for javac tag      fork  yes    executable  full-path-to-the-javac-you-want-to-use     Explaination of the properties can be found here

User · Answer

JAVACMD is an Ant specific environment variable  Ant doc says   JAVACMD   full path of the Java executable  Use this to invoke a different JVM than JAVA HOME bin java  exe    So  if your java exe full path is  C  Program Files Java jdk1 8 0 211 bin java exe  create a new environment variable called JAVACMD and set its value to the mentioned path  including  java exe   Note that you need to close and reopen your terminal  cmd  Powershell  etc  so the new environment variable takes effect

User · Answer

This is rather an old question  but I will add my notes for future references   I had a similar issue and fixed it by changing the order of the exports in the PATH variable   For example I was using a method of concatenating strings to my PATH by doing  this is just an example      gt  export PATH   PATH   JAVA HOME   If my variable PATH already had a java in it  the last value would be meaningless  thus the order would matter  To solve this I started inverting it by adding my variable first  then adding the PATH   Following this idea I inverted the order that ANT HOME was being exported  Adding JAVA HOME before ANT HOME   This could be just a coincidence  but it worked for me

User · Answer

Set your JAVA HOME environment variable with the required java version  in your case java 1 5   then in build xml use executable    JAVA HOME  bin javac  inside  lt javac gt  lt  javac gt  tag    example    lt target name  java compiler  description  Compiles the java code  gt       lt javac executable    JAVA HOME  bin javac  srcdir    src           destdir    build dir  classes  gt        lt  javac gt    lt  target gt

User · Answer

According to the ant manual  setting JAVA HOME should work - are you sure the changed setting is visible to ant   Alternatively  you could use the JAVACMD variable

[java] Ant is using wrong java version

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