Error: Could not find or load main class問題解決

錯誤如下:

D:>java Hello
Error: Could not find or load main class Hello

代碼如下：

import org.apache.log4j.Logger;
import org.apache.log4j.BasicConfigurator;
    
public class Hello {
    
    private static final Logger logger = Logger.getLogger(Hello.class);
    
    public  static  void main(String argv[]) {
    	BasicConfigurator.configure();
    	logger.debug("Hello world.");
    	logger.info("What a beatiful day.");
    }
}

Java環境變量設置有問題，沒有包括本目錄，解決方法一:
在命令行中指定Classpath
D:>java -classpath “.;D:\apache-log4j-1.2.16\log4j-1.2.16.ja
r” Hello
0 [main] DEBUG Hello - Hello world.
1 [main] INFO Hello - What a beatiful day.

解決方法二：
在Windows的環境變量的Classpath變量的最前面加上“.;”，這種方法一勞永逸。

輸出結果如下：
D:>java Hello
0 [main] DEBUG Hello - Hello world.
0 [main] INFO Hello - What a beatiful day.

Reference

What does “Could not find or load main class” mean?