Problems with setting the classpath in ant

Question

I'm having problems getting my Java program to run (it uses some third party JARs). I can compile it fine but when I call my run target in ant it says it can't find the class that I told it run in the classpath. Here's what my build.xml looks like:

<project basedir="." default="build">
<property name="build" value="build" />
<property name="src" value="." />
<property name="lib" value="lib" />

<path id="classpath">
    <fileset dir="${lib}">
        <include name="**/*.jar" />
    </fileset>
    <fileset dir="${build}">
        <include name="*.class" />
    </fileset>
</path>

<target name="build">
    <javac srcdir="${src}" destdir="${build}">
        <classpath refid="classpath" />
    </javac>
</target>

<target name="run">
    <java classname="FirstClass">
        <classpath refid="classpath" />
    </java>
</target>

Does anyone know what I might be doing wrong?

---

Here's my stack trace from ant:

ant run Buildfile: build.xml

run:
[java] Could not find GuiStarter. Make sure you have it in your classpath
[java] at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:138)
[java] at org.apache.tools.ant.taskdefs.Java.run(Java.java:764)
[java] at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:218)
[java] at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:132)
[java] at org.apache.tools.ant.taskdefs.Java.execute(Java.java:105)
[java] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
[java] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[java] at java.lang.reflect.Method.invoke(Method.java:616)
[java] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
[java] at org.apache.tools.ant.Task.perform(Task.java:348)
[java] at org.apache.tools.ant.Target.execute(Target.java:357)
[java] at org.apache.tools.ant.Target.performTasks(Target.java:385)
[java] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1337)
[java] at org.apache.tools.ant.Project.executeTarget(Project.java:1306)
[java] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
[java] at org.apache.tools.ant.Project.executeTargets(Project.java:1189)
[java] at org.apache.tools.ant.Main.runBuild(Main.java:758)
[java] at org.apache.tools.ant.Main.startAnt(Main.java:217)
[java] at org.apache.tools.ant.launch.Launcher.run(Launcher.java:257)
[java] at org.apache.tools.ant.launch.Launcher.main(Launcher.java:104)
[java] Java Result: -1

BUILD SUCCESSFUL Total time: 1 second

Answer 1

The way it is - only jars inside lib directory relative to your path are getting loaded. Do you have all of your 3-rd party jars there? There may be some run-time libraries that you don't need at compile time but which are missing at run time. If you post your stacktrace I'll tell you more :)

Answer 2

I think the problem is with your classpath path declaration. The build directory should be a <pathelement>

<path id="classpath">
    <fileset dir="${lib}">
        <include name="**/*.jar" />
    </fileset>
    <pathelement location="${build}" />
</path>

Also, I would only include 3-rd party jars in your classpath refid. So the whole block looks like.

<path id="3rd-party-classpath">
    <fileset dir="${lib}">
        <include name="**/*.jar" />
    </fileset>
</path>

<target name="build">
    <javac srcdir="${src}" destdir="${build}">
        <classpath refid="3rd-party-classpath" />
    </javac>
</target>

<target name="run">
    <java classname="FirstClass">
      <classpath>
        <pathelement location="${build}" />
        <path refid="3rd-party-classpath" />
      </classpath>
    </java>
</target>

Also, as DroidIn.net has pointed out, you should create a package for you program.

Answer 3

Try this , i could able to run my class.

<property name="src.dir" value="src" />
<property name="build.dir" value="build" />
<property name="classes.dir" value="${build.dir}/classes" />
<property name="jar.dir" value="${build.dir}/jar" />
<property name="main-class" value="sample.Sample" />

<target name="clean">
    <delete dir="${classes.dir}" />
</target>

<path id="classpath">
    <fileset dir="${jar.dir}">
        <include name="*.jar" />
    </fileset>
    <fileset dir="${classes.dir}">
        <include name="/*.class" />
    </fileset>
</path>

<target name="compile">
    <mkdir dir="${classes.dir}" />
    <javac srcdir="${src.dir}" destdir="${classes.dir}">
        <classpath refid="classpath" />
    </javac>
</target>

<target name="jar" depends="compile">
    <mkdir dir="${jar.dir}" />
    <jar destfile="${jar.dir}/${ant.project.name}.jar" basedir="${classes.dir}">
        <manifest>
            <attribute name="Main-Class" value="${main-class}" />
        </manifest>
    </jar>
</target>

<target name="run" depends="jar">
    <java classname="${main-class}">
        <classpath refid="classpath" />
    </java>
</target>

<target name="clean-build" depends="clean,jar" />

<target name="main" depends="clean,run" />