java - 如何解决ClassNotFoundException : com. beust.jcommander.ParameterException

Question

我是 JAVA 开发新手，在 Eclipse 中编译类时遇到以下问题。编译时报错如下:

“Java 虚拟机启动器错误:发生 JNI 错误，请检查您的安装并重试”

随后出现错误:

“Java 虚拟机启动器发生了 Java 异常。”

在控制台中，出现的错误如下:

*Exception in thread "main" java.lang.NoClassDefFoundError: com/beust/jcommander/ParameterException
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
at java.lang.Class.privateGetMethodRecursive(Unknown Source)
at java.lang.Class.getMethod0(Unknown Source)
at java.lang.Class.getMethod(Unknown Source)
at sun.launcher.LauncherHelper.validateMainClass(Unknown Source)
at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
Caused by: java.lang.ClassNotFoundException: com.beust.jcommander.ParameterException
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 7 more*

有人可以帮助我吗？感恩。

AppTest.java

package all_Exercices.Different_Browsers;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.ie.InternetExplorerDriver;
import org.testng.annotations.Parameters;


public class AppTest
{
    WebDriver driver;

    @Parameters("browser")
    public void verifypageTitle(String browserName) 
    {
        if(browserName.equalsIgnoreCase("firefox"))
        {
            driver = new FirefoxDriver();
        }
        else if(browserName.equalsIgnoreCase("chrome"))
        {
            System.setProperty("webdriver.chrome.driver", "C:\\SeleniumGecko\\chromedriver.exe");
            driver = new ChromeDriver();
        }
        else if(browserName.equalsIgnoreCase("IE"))
        {
            System.setProperty("webdriver.ie.driver", "C:\\SeleniumGecko\\IEDriverServer.exe");
            driver = new InternetExplorerDriver();
        }

        driver.manage().window().maximize();
        driver.get("https://shopcart-challenge.4all.com/");
        System.out.println(driver.getTitle());
        driver.quit();
    }
}

crossbrowser.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="Suite" parallel="tests">
  <test name="FirefoxTestCases">
  <parameter name="browser" value="firefox"/>
  <classes>
    <class name="all_Exercices.Different_Browsers.AppTest"/>
  </classes>    
  </test> <!--Test -->
    <test name="ChromeTestCases">
  <parameter name="browser" value="chrome"/>
  <classes>
    <class name="all_Exercices.Different_Browsers.AppTest"/>
  </classes>    
  </test> <!--Test -->
    <test name="IETestCases">
  <parameter name="browser" value="ie"/>
  <classes>
    <class name="all_Exercices.Different_Browsers.AppTest"/>
  </classes>    
  </test> <!--Test -->
</suite> <!--Suite -->

POM.XML

<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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>4all_Exercices</groupId>
  <artifactId>Different_Browsers</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>Different_Browsers</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

Answer 1

导致错误的原因

如果抛出 java.lang.ClassNotFoundException 或 java.lang.NoClassDefFoundError 异常，则意味着消息中提到的类(此处:com JVM 在类路径上找不到 .beust.jcommander.ParameterException)。

程序的任何部分，很可能是测试启动器(TestNG，或者在您的情况下为 JUnit)，似乎都使用命令行解析器Cedric Beust 的 JCommander。

如何解决

将所需的类(在本例中为整个 jar)添加到构建类路径应该使 JVM 能够找到并加载它。由于您有一个 Maven 项目，您只需在 dependencies 元素/标签内将依赖项添加到 POM.xml 即可:

<dependency>
  <groupId>com.beust</groupId>
  <artifactId>jcommander</artifactId>
  <version>1.71</version>
</dependency>

参见JCommander Download section .

另请参阅

这个问题描述了类似的问题:Getting "java.lang.NoClassDefFoundError: com/beust/jcommander/ParameterException"Exception