How to import JAVA sources into Eclipse?

Question

Java

The main problem lies in the imports. If you simply add sources, then all imports that do not belong to the standard libraries become invalid. How to fix such things? Of course, do not offer to fix it manually, there are a million classes :)
Screenshot:

Answer 1

For this, there are Maven / Gradle

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>org.mmocore</groupId>
  <artifactId>authserver</artifactId>
  <version>0.0.1</version>

  <name>authserver</name>
</project>

Then right click on the project: Configure -> Convert to Maven Project