In Java-land most people build and do dependency management with Maven or Gradle. In either case, these tools can pull from repositories based on the Maven format. The vast majority of popular libraries are in repo "Maven Central" and "just work" if added to your dependency list. A number of smaller, more specialized repos also exist, and it's trivial to add additional repos to your Maven/Gradle config as well.

You can search for libraries on mvnrepository.com, or your IDE can search the index. Also most libraries will include a section in the documentation that shows the details of the blob you have to put in your pom.xml / build.gradle file.