This page details some steps you can take to try and resolve any problems you may be having with Apache Ant. If you find you can't resolve the problem, then this page will help you collect some of the relevant information to provide in a bug report. This information will help the Ant developers understand and resolve the problem. Of course, not all the steps here will make sense for every problem you may encounter - these are just some suggestions to point you in the right direction.
Many tools include a version of Ant and some Operating Systems even install it by default now, so you may have a version of Ant installed that you haven't been aware of.
One of the first things to do is to run
to be sure. Also, we highly recommend that you run Ant with an empty CLASSPATH. If any other version of Ant can be loaded from the CLASSPATH, many types of errors may happen because of incompatible classes being loaded.
The first step to take when you have a problem with Ant is to read the manual entry for the task or concept that is giving you trouble. In particular, check the meaning of a task's attributes and nested elements. Perhaps an attribute is available that would provide the behavior you require. If you have problems with the manual itself, you can submit a documentation bug report (see below) to help us improve the Ant documentation.
If you're still having a problem, the next step is to try and
gather additional information about what Ant is doing.
Try running Ant with the
This will produce output that starts like the following:
Ant version 1.4.1 compiled on October 11 2001
Detected Java version: 1.3 in: D:\usr\local\java\jdk13\jre
Detected OS: Windows NT
parsing buildfile D:\ant\build.xml with URI = file:D:/ant/build.xml
Project base dir set to: D:\ant
[property] Loading Environment env.
[property] Loading D:\ant\conf.properties
Build sequence for target 'debug' is [debug]
Complete build sequence is [debug, gensrc, compile, jar, test]
. . .
You should be able to see from the trace more about what Ant
is doing and why it's taking a particular course of action.
If you need even more information, you can use the
-debug flag rather than
This will generally produce so much
output that you may want to save the output to a file and
analyze it in an editor. You can save the output using the
-logfile <filename> flag, or
Once you have all this debug information, how can you use it
to solve your problem? That will depend on the task in question
and the nature of your problem. Each task logs different aspects
of its operation, but it should give you an idea of what is going
on. For example, the
<javac> task logs the
reasons why it
chooses to compile particular class files and not others, along
with which compiler it is using and the arguments it will pass
to that compiler. The following partial trace shows why
<javac> is adding one class file but
This is followed by which compiler it will be using, the
arguments that will get passed to the compiler,
and a list of all the class files to be compiled.
[javac] Test.java omitted as D:\classes\Test.class is up to date.
[javac] Unset.java added as D:\classes\Unset.class is outdated.
[javac] Compiling 1 source file to D:\classes
[javac] Using classic compiler
[javac] Compilation args: -d D:\classes -classpath D:\classes;
D:\jdk118\classes.zip; -sourcepath D:\src\java -g:none
[javac] File to be compiled:
In many cases, Ant tasks are wrappers around OS commands or
other Java classes. In debug mode, many of these tasks will
print out the equivalent command line, as the
output does. If you are having a problem, it is often useful to
run the command directly from the command line, in the same way
Ant is running it, and see if the problem occurs from there
as well. The problem may be in the command that is being run,
or it may be in the way the Ant task is running the command.
You can also see the effect of changing attribute values on the
generated command line. This can help you to understand whether
you are using the correct attributes and values.
After examining the debug output, if you still believe that the problem you are having is caused by Ant, chances are that someone else may have already encountered this problem, and perhaps it has been fixed. The next step, therefore, would be to download the sources of ant, see svn.
Gump is building ant every night and using the ant built from the latest source to build a long list of open source projects. However, the version of ant built by gump is not available for download. Even if it were, it would not include most of the optional tasks.
We currently do not have nightly builds including the optional tasks.
If you are convinced that you have identified an unfixed bug, please turn to our document concerning the bug database.