I wrote this earlier on a Github gist, but putting it here for a consolidated reference.

Want to change Java Version/JAVA_HOME for Ant builds?

  1. Open ~/.antrc file by running vim ~/.antrc
  2. Add JAVACMD=<NEW_JAVA_HOME>/bin/java and save

The Ant wrapper script for Unix will source (read and evaluate) the file ~/.antrc before it does anything. On Windows, the Ant wrapper batch-file invokes %HOME%\antrc_pre.bat at the start and %HOME%\antrc_post.bat at the end. You can use these files, for example, to set/unset environment variables that should only be visible during the execution of Ant.

The wrapper scripts use the following environment variables (if set):

  • JAVACMD—full path of the Java executable. Use this to invoke a different JVM than JAVA_HOME/bin/java(.exe).
  • ANT_OPTS—command-line arguments that should be passed to the JVM. For example, you can define system properties or set the maximum Java heap size here.
  • ANT_ARGS—Ant command-line arguments. For example, set ANT_ARGS to point to a different logger, include a listener, and to include the -find flag. Note: If you include -find in ANT_ARGS, you should include the name of the build file to find, even if the file is called build.xml.

Source: https://ant.apache.org/manual/running.html