Document how to work with a non-"project" set of files

I'm very new to Java development and am learning by simply creating a few ad hoc files. I'm following a book that uses a folder/package structure of "ch01/sec01" which I mimicked in my VSC folder structure. I noticed that the plugin would always give an error for:

package ch01.sec01;

Saying that the package was actually "" instead. I ignored this error and just carried on but it bothered me. :) A friend pointed out that if I moved my files into a "src" folder, this would go away, and apparently this is the default if you make a new Java project, but as I was just playing around and not really doing a 'project', I never knew this was an issue.

My recommendation is that a quick note be adding to the Troubleshooting section of the readme.

Steps To Reproduce

1. Work with Java files w/o first making a Java project
2. Note that even though you have the right package, it gets flagged as an error.

打开 README 并找到 Troubleshooting 部分。添加一条简洁说明，解释在项目结构之外使用 Java 文件时出现的 package 警告，包括 src 文件夹的作用，然后验证新增说明与报告的复现步骤一致。