如何修复 Java 中的「包不存在」错误

# Introduction

As a Java developer, you will likely encounter the "package does not exist" error during your programming journey. This error occurs when the Java compiler cannot locate a package that your code is trying to use. This lab will guide you through understanding Java packages, creating a project that demonstrates the error, and then resolving the issue properly. By the end of this tutorial, you will understand how to fix and prevent this common error in your Java applications.