执行 jar 错误无法找到或加载主类

Question

抱歉另一个“无法找到或加载主类”的问题。我是 Java 新手。我搜索了一段时间，但找不到原因。我的项目是一个非常简单的项目，使用maven.mvn archetype:generate -DgroupId=mycompany -DartifactId=faker -DinteractiveMode=falsepom.xml（默认，不变）<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">  <modelVersion>4.0.0</modelVersion>  <groupId>mycompany</groupId>  <artifactId>faker</artifactId>  <packaging>jar</packaging>  <version>1.0-SNAPSHOT</version>  <name>faker</name>  <url>http://maven.apache.org</url>  <dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>3.8.1</version>      <scope>test</scope>    </dependency>  </dependencies></project>和源代码（默认，不变）package mycompany;public class App {    public static void main( String[] args ) {        System.out.println( "Hello World!" );    }}我用jar命令构建 jar 文件。~$ jar cvfm MyCompany.jar manifest.txt  src/main/java/mycompany/App.java# added manifest# adding: src/main/java/mycompany/App.java(in = 705) (out= 352)(deflated 50%)清单.txt~$ cat manifest.txt Main-Class: mycompany.App# (has an empty new line here)但是每当我执行它时，它都会给我以下错误：~$ java -jar MyCompany.jar Error: Could not find or load main class mycompany.App哪里错了？openjdk version "1.8.0_181"Apache Maven 3.5.2感谢@ohlec 和@Kayaman，更具体地说，这是解决它的方法。# get App.class~$ cd src/main/java/mycompany/ && javac App.java# back to faker folder~$ jar cvfm MyCompany.jar manifest.txt  -C src/main/java mycompany/App.class~$ java -jar MyCompany.jar# Hello World!