获取错误“无法找到或加载主类HelloWorld” [英] Getting error "cannot find or load main class HelloWorld"

问题描述

我有这个简单的代码：

public class HelloWorld{
    public static void main(String[] args){
        System.out.println("HelloWorld");
    }
}

文件名HelloWorld.java

And the filename HelloWorld.java

在命令提示符下，我输入：

In command prompt, I type in:

javac HelloWorld.java

java HelloWorld

（同一目录）

我收到错误：无法找到或加载主类HelloWorld

I am getting the error: "cannot find or load main class HelloWorld"

我确定它与不正确的安装无关，因为我重新安装了jdk和jre两次。

I'm sure it has nothing to do with improper installation because I reinstalled jdk and jre twice.

编辑：

之前有效，并且第二天，没有更改代码，目录或任何内容，它开始出错。

This was working before, and the next day, no change of code, directory, or anything, its started giving an error.

推荐答案

如果您有一个错误/不适当的CLASSPATH环境变量设置;例如当前目录不在类路径上。 （默认为......）

You could get this behaviour if you have an incorrect / inappropriate setting of the CLASSPATH environment variable; e.g. the current directory isn't on the classpath. (It is by default ... )

试试这个：

java -classpath . HelloWorld

假设有效......问题是你对classpath概念的理解。 Oracle文档对此进行了解释：

Assuming that works ... the problem is your understanding of the concept of the "classpath". This is explained well by the Oracle documentation:

• java & javac 命令文档......特别是 - classpath参数


• 设置类路径。


• Java教程 - PATH和CLASSPATH

• The java & javac command documentation ... particular the -classpath argument
• Setting the Classpath.
• The Java Tutorial - PATH and CLASSPATH

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