Once you have a package, you will want to import classes and/or interfaces—actually, class and/or interface names—from that package to your program, so it can use those classes and/or interfaces.

Importing an entire package should have no impact on the memory use at runtime (you pay for what you use, not what you can see).

As an example, the declaration import module java.base imports all 54 exported packages, effectively bringing a wide range of classes into scope from java.util to java.io.

The Java Tutorials ‘ Deployment Trail features the Packaging Programs in JAR Files lesson that includes the relevant section Setting Package Version Information.

The choice is a personal decision. I have more experience programming Java than Perl. After a long and difficult thought process, I decided to start in Java, reasoning that if I later needed to add ...