Php versions – Check URL/IP with port with regex

My Java 11/Android app has to check if the URL/IP the user entered could theoretically be valid (using myURL.trim().matches(regex)).

What should be valid (including variations):

• stackoverflow.com
• http://stackoverflow.com
• http://amazon.co.uk
• https://www.amazon.co.uk
• ftp://10.1.1.9
• 10.1.1.9:1234
• http://10.1.1.9:1234/bla

What shouldn’t be valid:

• http://bla
• bla
• "—" (without the "", had to add them because of formatting)
• 10.9
• 10.1.1.
• 10.1..1.9

I don’t care if the user enters e.g. "999.999.999.999", I only want to know if the syntax is theoretically correct, which it would be in this case.

So far I’ve been using this regex:

String regex1 = "((http|https|ftp)://)?((\w)*|([0-9]*)|([-|_])*)+([\.|/]((\w)*|([0-9]*)|([-|_])*))+";

… but now I want to check for the port too and ^ doesn’t support that. This other version supports ports:

String regex2 = "((http|https|ftp)://)?(([^/:.[:space:]]+(.[^/:.[:space:]]+)*)|([0-9](.[0-9]{3})))(:[0-9]+)?((/[^?#[:space:]]+)([^#[:space:]]+)?(#.+)?)?";

… but it returns true for strings like "http://bla" or "—".

I also tested this version by Microsoft:

String regex3 = "^(ht|f)tp(s?)\:\/\/[0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*(:(0-9)*)*(\/?)([a-zA-Z0-9\-\.\?\,\'\/\\\+&%\$#_]*)?$";

… but it doesn’t work for some of the above examples ("http://bla" and "http://10.1.1.9:1234/bla" are valid, "10.1.1.9" and "stackoverflow.com" aren’t) and I’m not sure how to get this long PHP version to work with java, as it complains about the "#" and ")".

I’m aware there’s already a lot of regex code for validating URLs floating around on stackoverflow and I already tested a bunch of other versions from the mega-thread (and other questions) but the ones that I could get Android Studio to accept didn’t work and my regex "knowledge" isn’t even remotely big enough to modify someone else’s code, let alone write my own.

How do I accomplish this?