build.xml

<?xml version="1.0"?>
<project name="test" default="run" basedir=".">
  <property environment="env" />

  <path id="cpath">
    <pathelement path="${env.CLASSPATH}" />
    <pathelement location="build" />
  </path>

  <target name="init" >
    <mkdir dir="build" />
  </target>

  <target name="compile" depends="init" >
    <javac fork="true" debug="true" srcdir="src" destdir="build" classpathref="cpath" />
  </target>

  <target name="run" depends="compile">
    <java fork="true" classname="test" classpathref="cpath" failonerror="true" />
  </target>

  <target name="clean">
    <delete dir="build" />
  </target>

</project>

output.txt

$ CLASSPATH=/usr/share/java/commons-lang-2.4.jar ant -v
Apache Ant version 1.7.1 compiled on November 10 2008
Buildfile: build.xml
Detected Java version: 1.6 in: /usr/lib/jvm/java-6-openjdk/jre
Detected OS: Linux
parsing buildfile /home/dreiss/javatest/build.xml with URI = file:/home/dreiss/javatest/build.xml
Project base dir set to: /home/dreiss/javatest
[antlib:org.apache.tools.ant] Could not load definitions from resource org/apache/tools/ant/antlib.xml. It could not be found.
 [property] Loading Environment env.
Build sequence for target(s) `run' is [init, compile, run]
Complete build sequence is [init, compile, run, clean, ]

init:
    [mkdir] Created dir: /home/dreiss/javatest/build

compile:
    [javac] test.java added as test.class doesn't exist.
    [javac] Compiling 1 source file to /home/dreiss/javatest/build
    [javac] Using external javac compiler
    [javac] Compilation arguments:
    [javac] '-d'
    [javac] '/home/dreiss/javatest/build'
    [javac] '-classpath'
    [javac] '/home/dreiss/javatest/build:/usr/share/java/commons-lang-2.4.jar:/usr/share/ant/lib/ant-launcher.jar:/usr/share/java/xmlParserAPIs.jar:/usr/share/java/xercesImpl.jar:/usr/share/ant/lib/ant-javamail.jar:/usr/share/ant/lib/ant.jar:/usr/share/ant/lib/ant-apache-bsf.jar:/usr/share/ant/lib/ant-jsch.jar:/usr/share/ant/lib/ant-commons-net.jar:/usr/share/ant/lib/ant-apache-bcel.jar:/usr/share/ant/lib/ant-swing.jar:/usr/share/ant/lib/ant-junit.jar:/usr/share/ant/lib/ant-apache-log4j.jar:/usr/share/ant/lib/ant-jmf.jar:/usr/share/ant/lib/ant-trax.jar:/usr/share/ant/lib/ant-jdepend.jar:/usr/share/ant/lib/ant-nodeps.jar:/usr/share/ant/lib/ant-apache-regexp.jar:/usr/share/ant/lib/ant-commons-logging.jar:/usr/share/ant/lib/ant-antlr.jar:/usr/share/ant/lib/ant-apache-oro.jar:/usr/share/ant/lib/ant-apache-resolver.jar:/usr/lib/jvm/java-6-openjdk/lib/tools.jar'
    [javac] '-sourcepath'
    [javac] '/home/dreiss/javatest/src'
    [javac] '-g'
    [javac] 
    [javac] The ' characters around the executable and arguments are
    [javac] not part of the command.
    [javac] File to be compiled:
    [javac]     /home/dreiss/javatest/src/test.java

run:
     [java] Executing '/usr/lib/jvm/java-6-openjdk/jre/bin/java' with arguments:
     [java] '-classpath'
     [java] '/usr/share/java/commons-lang-2.4.jar:/home/dreiss/javatest/build'
     [java] 'test'
     [java] 
     [java] The ' characters around the executable and arguments are
     [java] not part of the command.

BUILD SUCCESSFUL
Total time: 1 second

test.java

import org.apache.commons.lang.mutable.MutableInt;

public class test {
  public static void main(String args[]) {
    new MutableInt(0);
  }
}