Java 错误的类路径？为什么我仍然没有发现错误？

我正在用Java编写学校的项目（离散模拟库），当我运行示例应用程序时，仍然会遇到以下错误：

 [java] Exception in thread "main" java.lang.NoClassDefFoundError: /home/lut/Plocha/IMS/examples/Random/random/RandomTest
 [java] Caused by: java.lang.ClassNotFoundException: .home.lut.Plocha.IMS.examples.Random.random.RandomTest
 [java]     at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
 ...
 [java]     at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
 [java] Could not find the main class: /home/lut/Plocha/IMS/examples/Random/random.RandomTest. Program will exit.
 [java] Java Result: 1

（/home/lut/Plocha/IMS是根目录。在下面的文件树中，它标记为。-dot）

我在根目录中有一个库。还有目录

示例

，其中有使用此库的小型示例应用程序，每个应用程序都有自己的build ant脚本

目录结构：

.
├── build.xml   <-- library build-file, examples are not included in this build
├── doc
├── examples
│   ├── Random
│   │   ├── build.xml    <-- example app buil-file
│   │   └── src
│   │       └── random
│   │           └── RandomTest.java  <-- main class of the example
│   └── Calendar
│       ├── build.xml, src, etc. inside
│       ...
├── dest      <-- after library build, dsim.jar is here
├── build
└── src       <-- source files of the library
    └── ims
        ├── Distribution
        │   └── RandomGenerator.java
        ├── Exception
        │   ├── RandomException.java
        │   └── SimulationException.java
        └── SimObjects
            ├── Entity.java
            ├── Event.java
            ├── Facility.java
            ...

RandomTest.java文件以以下行开头：

package random;

import ims.Distribution.RandomGenerator;
import ims.Exception.SimulationException;
import ims.SimObjects.Histogram;

public class RandomTest {
    public static void main(String[] args) throws SimulationException {

我试着在谷歌上搜索，有好几篇关于类路径及其问题的帖子，但即使我无法确定问题出在哪里。我做错了什么？我想念什么

---

非常感谢。

类名是

random.RandomTest

这是什么

.home.lut.Plocha.IMS.examples.Random.random.RandomTest

类加载器为什么要查找这个

这是一个通用的build.xml，它对我来说非常有效。创建目录结构并查看它是否对您进行排序：

<?xml version="1.0" encoding="UTF-8"?>
<project name="xslt-converter" basedir="." default="package">

    <property name="version" value="1.6"/>
    <property name="haltonfailure" value="no"/>

    <property name="out" value="out"/>

    <property name="production.src" value="src"/>
    <property name="production.lib" value="lib"/>
    <property name="production.resources" value="config"/>
    <property name="production.classes" value="${out}/production/${ant.project.name}"/>

    <property name="test.src" value="test"/>
    <property name="test.lib" value="lib"/>
    <property name="test.resources" value="config"/>
    <property name="test.classes" value="${out}/test/${ant.project.name}"/>

    <property name="exploded" value="out/exploded/${ant.project.name}"/>
    <property name="exploded.classes" value="${exploded}/WEB-INF/classes"/>
    <property name="exploded.lib" value="${exploded}/WEB-INF/lib"/>

    <property name="reports.out" value="${out}/reports"/>
    <property name="junit.out" value="${reports.out}/junit"/>
    <property name="testng.out" value="${reports.out}/testng"/>

    <path id="production.class.path">
        <pathelement location="${production.classes}"/>
        <pathelement location="${production.resources}"/>
        <fileset dir="${production.lib}">
            <include name="**/*.jar"/>
            <exclude name="**/junit*.jar"/>
            <exclude name="**/*test*.jar"/>
        </fileset>
    </path>

    <path id="test.class.path">                            
        <path refid="production.class.path"/>
        <pathelement location="${test.classes}"/>
        <pathelement location="${test.resources}"/>
        <fileset dir="${test.lib}">
            <include name="**/junit*.jar"/>
            <include name="**/*test*.jar"/>
        </fileset>
    </path>

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

    <available file="${out}" property="outputExists"/>

    <target name="clean" description="remove all generated artifacts" if="outputExists">
        <delete dir="${out}" includeEmptyDirs="true"/>
        <delete dir="${reports.out}" includeEmptyDirs="true"/>
    </target>

    <target name="create" description="create the output directories" unless="outputExists">
        <mkdir dir="${production.classes}"/>
        <mkdir dir="${test.classes}"/>
        <mkdir dir="${reports.out}"/>
        <mkdir dir="${junit.out}"/>
        <mkdir dir="${testng.out}"/>
        <mkdir dir="${exploded.classes}"/>
        <mkdir dir="${exploded.lib}"/>
    </target>

    <target name="compile" description="compile all .java source files" depends="create">
        <!-- Debug output
                <property name="production.class.path" refid="production.class.path"/>
                <echo message="${production.class.path}"/>
        -->
        <javac srcdir="src" destdir="${out}/production/${ant.project.name}" debug="on" source="${version}">
            <classpath refid="production.class.path"/>
            <include name="**/*.java"/>
            <exclude name="**/*Test.java"/>
        </javac>
        <javac srcdir="${test.src}" destdir="${out}/test/${ant.project.name}" debug="on" source="${version}">
            <classpath refid="test.class.path"/>
            <include name="**/*Test.java"/>
        </javac>
    </target>

    <target name="junit-test" description="run all junit tests" depends="compile">
        <!-- Debug output
                <property name="test.class.path" refid="test.class.path"/>
                <echo message="${test.class.path}"/>
        -->
        <junit printsummary="yes" haltonfailure="${haltonfailure}">
            <classpath refid="test.class.path"/>
            <formatter type="xml"/>
            <batchtest fork="yes" todir="${junit.out}">
                <fileset dir="${test.src}">
                    <include name="**/*Test.java"/>
                </fileset>
            </batchtest>
        </junit>
        <junitreport todir="${junit.out}">
            <fileset dir="${junit.out}">
                <include name="TEST-*.xml"/>
            </fileset>
            <report todir="${junit.out}" format="frames"/>
        </junitreport>
    </target>

    <taskdef resource="testngtasks" classpathref="testng.class.path"/>
    <target name="testng-test" description="run all testng tests" depends="compile">
        <!-- Debug output
                <property name="test.class.path" refid="test.class.path"/>
                <echo message="${test.class.path}"/>
        -->
        <testng classpathref="test.class.path" outputDir="${testng.out}" haltOnFailure="${haltonfailure}" verbose="2" parallel="methods" threadcount="50">
            <classfileset dir="${out}/test/${ant.project.name}" includes="**/*.class"/>
        </testng>
    </target>

    <target name="exploded" description="create exploded deployment" depends="testng-test">
        <copy todir="${exploded.classes}">
            <fileset dir="${production.classes}"/>
        </copy>
        <copy todir="${exploded.lib}">
            <fileset dir="${production.lib}"/>
        </copy>
    </target>

    <target name="package" description="create package file" depends="exploded">
        <jar destfile="${out}/${ant.project.name}.jar" basedir="${production.classes}" includes="**/*.class"/>
    </target>

</project>

---

好的，所以问题是属性atribute名称不正确（我在主类属性定义中有位置而不是值）

但是为什么呢？存在类路径引用。还是jar和classpath属性的排他性问题（在frist@duffymo的答案下的注释）？如何修复build.xml以使其正常工作？

---

谢谢。

提示：使用

jarxfjarfile

提取您的jar，然后检查META-INF/manifest.mf。它在Main类中说明了什么？Main类：/home/lut/Plocha/IMS/examples/Random/Random.RandomTest-/home/lut/Plocha/IMS是根目录（在标记为-dot的文件树中）是否允许并正确处理-jar和-classpath的组合？我通常用一个或另一个。不，它们是相互排斥的。如果为可执行JAR设置类路径，则必须将其添加到清单中；请参阅“.home.lut.Plocha.IMS”是根目录，在标记为的文件树中。圆点。我不知道类加载器在找这个。。。这可能就是我要问的。。。

<?xml version="1.0" encoding="UTF-8"?>
<project name="xslt-converter" basedir="." default="package">

    <property name="version" value="1.6"/>
    <property name="haltonfailure" value="no"/>

    <property name="out" value="out"/>

    <property name="production.src" value="src"/>
    <property name="production.lib" value="lib"/>
    <property name="production.resources" value="config"/>
    <property name="production.classes" value="${out}/production/${ant.project.name}"/>

    <property name="test.src" value="test"/>
    <property name="test.lib" value="lib"/>
    <property name="test.resources" value="config"/>
    <property name="test.classes" value="${out}/test/${ant.project.name}"/>

    <property name="exploded" value="out/exploded/${ant.project.name}"/>
    <property name="exploded.classes" value="${exploded}/WEB-INF/classes"/>
    <property name="exploded.lib" value="${exploded}/WEB-INF/lib"/>

    <property name="reports.out" value="${out}/reports"/>
    <property name="junit.out" value="${reports.out}/junit"/>
    <property name="testng.out" value="${reports.out}/testng"/>

    <path id="production.class.path">
        <pathelement location="${production.classes}"/>
        <pathelement location="${production.resources}"/>
        <fileset dir="${production.lib}">
            <include name="**/*.jar"/>
            <exclude name="**/junit*.jar"/>
            <exclude name="**/*test*.jar"/>
        </fileset>
    </path>

    <path id="test.class.path">                            
        <path refid="production.class.path"/>
        <pathelement location="${test.classes}"/>
        <pathelement location="${test.resources}"/>
        <fileset dir="${test.lib}">
            <include name="**/junit*.jar"/>
            <include name="**/*test*.jar"/>
        </fileset>
    </path>

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

    <available file="${out}" property="outputExists"/>

    <target name="clean" description="remove all generated artifacts" if="outputExists">
        <delete dir="${out}" includeEmptyDirs="true"/>
        <delete dir="${reports.out}" includeEmptyDirs="true"/>
    </target>

    <target name="create" description="create the output directories" unless="outputExists">
        <mkdir dir="${production.classes}"/>
        <mkdir dir="${test.classes}"/>
        <mkdir dir="${reports.out}"/>
        <mkdir dir="${junit.out}"/>
        <mkdir dir="${testng.out}"/>
        <mkdir dir="${exploded.classes}"/>
        <mkdir dir="${exploded.lib}"/>
    </target>

    <target name="compile" description="compile all .java source files" depends="create">
        <!-- Debug output
                <property name="production.class.path" refid="production.class.path"/>
                <echo message="${production.class.path}"/>
        -->
        <javac srcdir="src" destdir="${out}/production/${ant.project.name}" debug="on" source="${version}">
            <classpath refid="production.class.path"/>
            <include name="**/*.java"/>
            <exclude name="**/*Test.java"/>
        </javac>
        <javac srcdir="${test.src}" destdir="${out}/test/${ant.project.name}" debug="on" source="${version}">
            <classpath refid="test.class.path"/>
            <include name="**/*Test.java"/>
        </javac>
    </target>

    <target name="junit-test" description="run all junit tests" depends="compile">
        <!-- Debug output
                <property name="test.class.path" refid="test.class.path"/>
                <echo message="${test.class.path}"/>
        -->
        <junit printsummary="yes" haltonfailure="${haltonfailure}">
            <classpath refid="test.class.path"/>
            <formatter type="xml"/>
            <batchtest fork="yes" todir="${junit.out}">
                <fileset dir="${test.src}">
                    <include name="**/*Test.java"/>
                </fileset>
            </batchtest>
        </junit>
        <junitreport todir="${junit.out}">
            <fileset dir="${junit.out}">
                <include name="TEST-*.xml"/>
            </fileset>
            <report todir="${junit.out}" format="frames"/>
        </junitreport>
    </target>

    <taskdef resource="testngtasks" classpathref="testng.class.path"/>
    <target name="testng-test" description="run all testng tests" depends="compile">
        <!-- Debug output
                <property name="test.class.path" refid="test.class.path"/>
                <echo message="${test.class.path}"/>
        -->
        <testng classpathref="test.class.path" outputDir="${testng.out}" haltOnFailure="${haltonfailure}" verbose="2" parallel="methods" threadcount="50">
            <classfileset dir="${out}/test/${ant.project.name}" includes="**/*.class"/>
        </testng>
    </target>

    <target name="exploded" description="create exploded deployment" depends="testng-test">
        <copy todir="${exploded.classes}">
            <fileset dir="${production.classes}"/>
        </copy>
        <copy todir="${exploded.lib}">
            <fileset dir="${production.lib}"/>
        </copy>
    </target>

    <target name="package" description="create package file" depends="exploded">
        <jar destfile="${out}/${ant.project.name}.jar" basedir="${production.classes}" includes="**/*.class"/>
    </target>

</project>

<property name="main-class" location="random.RandomTest"/>
<!-- shoudl be -->
<property name="main-class" value="random.RandomTest"/>

[java] java.lang.NoClassDefFoundError: ims/Exception/SimulationException
[java] Caused by: java.lang.ClassNotFoundException: ims.Exception.SimulationException