Java .jar 错误 - 无法找到或加载主类

.jar error - could not find or load main class

提问by Blrp

I tried to put HelloWorld in a .jar file and running it, but it doesn't work. I created the java file and typed in the program, and then wrote in cmd:

我试图将 HelloWorld 放在一个 .jar 文件中并运行它，但它不起作用。我创建了java文件并在程序中输入，然后在cmd中写入：

javac HelloWorld.java
java HelloWorld

and it worked. Then I entered

它奏效了。然后我进入

echo Main-Class: HelloWorld >manifest.txt
jar cvfm HelloWorld.jar manifest.txt HelloWorld.class

and got the output

并得到输出

added manifest
adding: HelloWorld.class(in = 426) (out= 288)(deflated 32%)

I then entered

然后我进入

java -jar HelloWorld.jar
HelloWorld.jar

and the first line worked, while the second line gave me an error:

第一行有效，而第二行给了我一个错误：

Error: Could not find or load main class path\HelloWorld.jar

which is the same output I got (in a rapidly closing window) when I tried to open it with the java.exe file in 64 bit jre7\bin, jdk1.7.0_51\bin, jdk1.7.0_51\jre\bin, as well as 32 bit jre7\bin. I've uninstalled and reinstalled both my jre and jdk and recreated my .class and .jar files, but the problem persists. I'm on win8.

当我尝试使用 64 位 jre7\bin、jdk1.7.0_51\bin、jdk1.7.0_51\jre\bin 中的 java.exe 文件打开它时，我得到的输出（在快速关闭的窗口中）相同，如以及 32 位 jre7\bin。我已经卸载并重新安装了我的 jre 和 jdk，并重新创建了我的 .class 和 .jar 文件，但问题仍然存在。我是win8。

Edit: I tried to do as aetheria suggested, but no luck. I put HelloWorld.java in path\com\stackoverflow\user\blrp, compiled it, and it worked by entering

编辑：我试着按照 aetheria 的建议去做，但没有运气。我把HelloWorld.java放在path\com\stackoverflow\user\blrp中，编译，输入

java com.stackoverflow.user.blrp.HelloWorld

in path. I then created the manifest and jar by:

在路径中。然后我通过以下方式创建了清单和 jar：

(echo Manifest-Version: 1.0
echo Class-Path: .
echo Main-Class: com.stackoverflow.user.blrp.HelloWorld) >manifest.txt
jar cvfm HelloWorld.jar manifest.txt com\stackoverflow\user\blrp\HelloWorld.class

and got the output

并得到输出

added manifest
adding: com/stackoverflow/user/blrp/HelloWorld.class(in = 454) (out= 312)(deflat
ed 31%)

but still, java -jar HelloWorld.jar worked and HelloWorld.jar didn't (same error). I also tried not doing the package thing, just the Class-Path in manifest, same result.

但是， java -jar HelloWorld.jar 仍然有效，而 HelloWorld.jar 没有（相同的错误）。我也尝试不做包的事情，只做清单中的类路径，结果相同。

(Also, I solved the problem prior to asking the question by use of a .bat file, but it'd still be sweet to get that jar working.)

（另外，我在使用 .bat 文件提出问题之前解决了这个问题，但让那个 jar 工作仍然很好。）

采纳答案by Blrp

Thanks jbaliuka for the suggestion. I opened the registry editor (by typing regedit in cmd) and going to HKEY_CLASSES_ROOT > jarfile > shell > open > command, then opening (Default) and changing the value from

感谢 jbaliuka 的建议。我打开了注册表编辑器（通过在 cmd 中键入 regedit）并转到 HKEY_CLASSES_ROOT > jarfile > shell > open > command，然后打开（默认）并更改值

"C:\Program Files\Java\jre7\bin\javaw.exe" -jar "%1" %*

"C:\Program Files\Java\jre7\bin\javaw.exe" -jar "%1" %*

to

到

"C:\Program Files\Java\jre7\bin\java.exe" -jar "%1" %*

"C:\Program Files\Java\jre7\bin\java.exe" -jar "%1" %*

(I just removed the w in javaw.exe.) After that you have to right click a jar -> open with -> choose default program -> navigate to your java folder and open \jre7\bin\java.exe (or any other java.exe file in you java folder). If it doesn't work, try switching to javaw.exe, open a jar file with it, then switch back.

（我刚刚删除了 javaw.exe 中的 w。）之后，您必须右键单击一个 jar -> 打开方式 -> 选择默认程序 -> 导航到您的 java 文件夹并打开 \jre7\bin\java.exe（或任何java文件夹中的其他java.exe文件）。如果它不起作用，请尝试切换到 javaw.exe，用它打开一个 jar 文件，然后切换回来。

I don't know anything about editing the registry except that it's dangerous, so you might wanna back it up before doing this (in the top bar, File>Export).

我对编辑注册表一无所知，只是它很危险，因此您可能希望在执行此操作之前对其进行备份（在顶部栏中，文件>导出）。

回答by ???v?т?

You can always run this:

你总是可以运行这个：

java -cp HelloWorld.jar HelloWorld

-cp HelloWorld.jaradds the jar to the classpath, then HelloWorldruns the class you wrote.

-cp HelloWorld.jar将 jar 添加到类路径，然后HelloWorld运行您编写的类。

To create a runnable jar with a main class with no package, add Class-Path: .to the manifest:

要使用没有包的主类创建可运行的 jar，请添加Class-Path: .到清单中：

Manifest-Version: 1.0
Class-Path: .
Main-Class: HelloWorld

I would advise using a packageto give your class its own namespace. E.g.

我建议使用 apackage为您的类提供自己的命名空间。例如

package com.stackoverflow.user.blrp;

public class HelloWorld {
    ...
}

回答by EuroTech

I found this question when I was looking for the answer to the above question. But in my case the issue was the use of an 'en dash' rather than a 'dash'. Check which dash you are using, it might be the wrong one. I hope this answer speeds up someone else's search, a comment like this could have saved me a bit of time.

我在寻找上述问题的答案时发现了这个问题。但就我而言，问题是使用“破折号”而不是“破折号”。检查您使用的是哪个破折号，它可能是错误的。我希望这个答案可以加快其他人的搜索速度，这样的评论可以为我节省一些时间。

回答by MoHaN K RaJ

I Faced the same issue while installing a setup using a jar file. Solution thta worked for me is

我在使用 jar 文件安装设置时遇到了同样的问题。对我有用的解决方案是

1. open command prompt as administrator
2. Go to jdk bin directory (Ex.C:\Program Files\Java\jdk1.8.0_73\bin)
3. now execute java -jar <<jar fully qualified path>>

1. 以管理员身份打开命令提示符
2. 进入 jdk bin 目录 (Ex.C:\Program Files\Java\jdk1.8.0_73\bin)
3. 现在执行 java -jar <<jar fully qualified path>>

It worked for me :)

它对我有用:)

回答by wintoch

Had this problem couldn't find the answer so i went looking on other threads, I found that i was making my app with 1.8 but for some reason my jre was out dated even though i remember updating it. I downloaded the lastes jre 8 and the jar file runs perfectly. Hope this helps.

如果这个问题找不到答案，所以我去寻找其他线程，我发现我正在使用 1.8 制作我的应用程序，但由于某种原因我的 jre 已经过时了，即使我记得更新它。我下载了 lastes jre 8 并且 jar 文件运行完美。希望这可以帮助。