Run a compiled Java file under cmd with the "Cannot find or Load main class" issue with Java commands

What is said on the Internet, I summed up a bit, and then I recently encountered a situation online as if no one had encountered, posted here

1, environment variables, generally can compile files, it is not the amount of environmental variables

2, without the package name, such as the AAA package below the Hello.java compiled Hello.class runtime to write this Java Aaa.hello

3, also I encountered a situation, the file path in Chinese, and then changed the folder name to the English name to solve.

Run a compiled Java file under cmd with the "Cannot find or Load main class" issue with Java commands