Android replace with regex

Question

I have a string in Android. I would like to wrap all the instances of 4 or more continuous digits with some html. I imagine this will be done with regex, but I have a hard time getting even the most basic regular expressions to work.

Can someone help me with this?

I would like to change:

var input = "My phone is 1234567890 and my office is 7894561230";

To

var output = "My phone is <u>1234567890</u> and my office is <u>7894561230</u>";

Answer 1

This will do it:

String input = "My phone is 1234567890 and my office is 7894561230";
String regex = "\\d{4,}";
String output = input.replaceAll(regex, "<u>$0</u>");
System.out.println(output);