Ant allows the build process to be monitored using listeners and loggers.

Listeners

Ant provides following events to be captured using listeners.

build started
build finished
target started
target finished
task started
task finished
message logged

Custom listeners can be registered on command line using -listener argument.

Loggers

Loggers extends listeners capabilities and add the following features

Can log information to console or file using -logfile argument
Can log using logging levels like -quiet, -verbose, -debug
Are emacs-mode aware

Built-in Listeners/loggers

org.apache.tools.ant.DefaultLogger − The logger used implicitly unless overridden with the -logger command-line switch.
org.apache.tools.ant.NoBannerLogger − This logger omits output of empty target output.
org.apache.tools.ant.listener.MailLogger − Extends DefaultLogger such that output is still generated the same, and when the build is finished an e-mail can be sent.
org.apache.tools.ant.listener.AnsiColorLogger − Colorifies the build output.
org.apache.tools.ant.listener.Log4jListener − Passes events to Apache Log4j for highly customizable logging.
org.apache.tools.ant.XmlLogger − Writes the build information to an XML file.
org.apache.tools.ant.TimestampedLogger − Prints the time that a build finished
org.apache.tools.ant.listener.BigProjectLogger − Prints the project name every target
org.apache.tools.ant.listener.SimpleBigProjectLogger − Prints the project name for subprojects only, otherwise like NoBannerLogger Since Ant 1.8.1
org.apache.tools.ant.listener.ProfileLogger − The default logger, with start times, end times and durations added for each task and target.

Example

Create build.xml with the following content:

<?xml version="1.0"?>
<project name="sample" basedir="." default="copy">
   <target name="copy">
     <echo>File Copied</echo>
   </target>
</project>

Output

Running Ant on the above build file produces the following output −

D:\Projects\ant>ant -logger org.apache.tools.ant.listener.TimestampedLogger
Buildfile: D:\Projects\ant\build.xml

copy:
     [echo] File Copied

BUILD SUCCESSFUL - at 26/08/25, 9:30?am
Total time: 0 seconds

D:\Projects\ant\>ant -logger org.apache.tools.ant.XmlLogger -verbose -logfile build_log.xml
Apache Ant(TM) version 1.10.15 compiled on August 25 2024
Trying the default build file: build.xml
Buildfile: D:\Projects\ant\build.xml

Now you can check build_log.xml file is created with relevant logs.

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