Java is just not made for quick prototyping. In production, the URL will come from somewhere, not written by hand, so it would need to be checked anyway. Sadly there's no quick-prototyping mode in Java where you can say, just call this URL string an don't bother checking.

Another example is the inability to just read a local file into a string with a simple API call. It's this way, again, because in production the program has to reason about paths and file systems and can't make assumptions about the validity (or size) of the file you just want to load and play with.

In production code, no matter the language, you have to guard against these issues. The nice thing about objects (immutable, anyway), is that once constructed and validated, they do not require tedious validation at every method and client they are passed into. That actually results in less boilerplate, and less test writing.

So just remember, Java always assumes your code is production-bound and requires upfront planning and checking. That's why it's unpleasant to prototype with.