Problems with setting the classpath in ant

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.taskd开发者_如何学Cefs.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

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.

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 :)

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" />

I had exactly the same problem. To avoid it, I was helped by deleting the "package" line at the very top in the Java code. After that, my VS Studio started complaining that this line was missing, but the xml code was executed successfully)))