Java &引用；无法加载com.apple.laf.AquaLookAndFeel“；使用Ant执行JAR文件时出错

我有一个Ant文件：

<?xml version="1.0"?>
<project name="tetris" default="all" basedir=".">
    <description>
        simple example build file
</description>
<!-- set global properties for this build -->
<property name="name" value="tetris"/>
<property name="src" location="src"/>
<property name="bin" location="bin"/>
<property name="dist" location="dist"/>
<property name="classpath" value="${dist}/${name}.jar"/>
<property name="main" value="com.els.test.Game"/>

<target name="init">
    <!-- Create the time stamp -->
    <tstamp/>
    <!-- Create the bin directory structure used by compile -->
    <mkdir dir="${bin}"/>
</target>

<target name="compile" depends="init"
                        description="compile the source">
    <!-- Compile the java code from ${src} into ${bin} -->
    <javac srcdir="${src}" destdir="${bin}" debug="on" deprecation="on"/>
</target>

<target name="dist" depends="compile"
                        description="generate the distribution">
    <!-- Create the distribution directory -->
    <mkdir dir="${dist}"/>

    <!-- Put everything in ${bin} into the MyProject-${DSTAMP}.jar file -->
    <!-- <jar jarfile="${dist}/MyProject-${DSTAMP}.jar" basedir="${bin}"/> -->
    <jar jarfile="${dist}/${name}.jar" basedir="${bin}"/>
</target>

<target name="run" depends="dist"
                        description="Run the program">
    <java classname="${main}"
                        classpath="${classpath}"/>
</target>

<!-- Delete the ${bin} directory trees -->
<target name="clean"
                description="clean up">
    <delete dir="${bin}"/>
    <mkdir dir="${bin}"/>
    <delete dir="${dist}"/>
    <mkdir dir="${dist}"/>
</target>

<target name="all" depends="clean,compile,dist,run"/>

</project>

---

build.xml文件怎么样了？

我正在macOS Catalina 10.15.1上运行JDK.Java.net中的Java JDK-14和Ant.apache.org中的Ant apache-Ant-1.10.7。在build.xml中为java任务添加fork=“true”解决了这个问题。build.xml文件附在下面：

<project name="Threads" default="dist" basedir=".">
    <description>
        Decision screen.
    </description>

    <property name="src" location="sources"/>
    <property name="build" location="classes"/>
    <property name="dist" location="dist"/>
    <property name="resources" location="resources"/>

    <target name="init">
        <tstamp/>
        <mkdir dir="${build}"/>
        <mkdir dir="${dist}"/>
    </target>

    <target name="compile" depends="init" description="compile the source">
        <!-- Compile the Java code from ${src} into ${build} -->
        <javac srcdir="${src}" destdir="${build}" includeantruntime="false"/>
    </target>

    <target name="DecisionScreen" depends="compile" description="Run program DecisionScreen">
        <!-- HERE IS THE CHANGE -->
        <java classname="Decision.DecisionScreen" fork="true">
            <classpath>
                <pathelement path="${build}"/>
            </classpath>
        </java>
    </target>

    <target name="dist" depends="compile" description="generate the distribution">
        <!-- Create the distribution directory -->
            <mkdir dir="${dist}/lib"/>
            <jar jarfile="${dist}/lib/Decision-${DSTAMP}.jar" basedir="${build}">
                <manifest>
                    <attribute name="Main-Class" value="Decision.DecisionScreen"/>
                </manifest>
            </jar>
    </target>

    <target name="clean" description="clean up">
        <!-- Delete the ${build} and ${dist} directory trees -->
        <delete dir="${build}"/>
        <delete dir="${dist}"/>
    </target>
</project>

---

“java.lang.Error:无法加载apple.laf.AquaLookAndFeel”不再出现。

您是否验证了Ant使用的是哪个java版本，以及是否在提示符下运行程序？如果是，您是否尝试使用不同的Java版本？

$ ant DecisionScreen
$ java -cp classes Decision.DecisionScreen
$ java -jar dist/lib/Decision-20200306.jar