Question

If one adds many framework dependencies to a Java application, will this increase its memory footprint drastically, because it preloads all libraries at startup or is that a more lazy behaviour which would load only the needed classes when you actually need it (e.g. import statements or even later)?

Could adding many dependencies also have other negative side effects that a Java developer should be aware of?

Answer 1

Classes will only be loaded as required (referenced by other classes via import etc.)

The headache with multiple frameworks is that you have to manage their shared dependencies. e.g. Framework A requires Logging Framework X, but Framework B requires Logging Framework Y.

These problems aren’t insurmountable, but you have to keep track of them. When you upgrade Framework A, you may well end up with a ripple effect, in which you have to update a corresponding dependency. That then requires another framework component update, and so on.

e.g. Framework A gets upgraded, and requires an update to Log4J. THat then forces you to update Framework B to a version compatible with your new Log4J, and so on.

If you have multiple framework requirements, this may in fact point to a requirement to subdivide your application accordingly (into different deployables/services etc.).