Quick Documentation
"Quick Documentation" is different from "External Documentation". For "Quick Documentation" you just need to configure your dependencies to include sources.
Do you have a Maven or Gradle project?
For Gradle and IntelliJ you can use the gradle-intellij-plugin in your build.gradle(.kts)
file. It has a downloadSources
option, which is true by default.
For Maven, there is an option to automatically download sources, documenation, and annotations in the IntelliJ settings under "Maven" > "Importing".
To see whether it's working or to do it manually, go to "Project Structure" > "Project Settings" > "Libraries" in IntelliJ. You can see and manually add or modify the source JARs and documentation URLs for all your libraries.
External Documentation
For external documentation (opening JavaDoc in the browser), you can tell IntelliJ to download the JavaDoc with the idea Gradle plugin like this:
idea {
module {
downloadJavadoc = true
//or in Gradle Kotlin DSL:
//isDownloadJavaDoc = true
}
}
For Maven the option is again in the IntelliJ settings.