I'm trying to replace the last dot in a String using a regular expression.
Let's say I have the following String:
String string = "hello.world.how.are.you!";
I want to replace the last dot with an exclamation mark such that the result is:
"hello.world.how.are!you!"
I have tried various expressions using the method String.replaceAll(String, String) without any luck.
One way would be:
string = string.replaceAll("^(.*)\\.(.*)$","$1!$2");
Alternatively you can use negative lookahead as:
string = string.replaceAll("\\.(?!.*\\.)","!");
^(.*)\\.(.*?)$ ?Although you can use a regex, it's sometimes best to step back and just do it the old-fashioned way. I've always been of the belief that, if you can't think of a regex to do it in about two minutes, it's probably not suited to a regex solution.
No doubt get some wonderful regex answers here. Some of them may even be readable :-)
You can use lastIndexOf to get the last occurrence and substring to build a new string: This complete program shows how:
public class testprog {
public static String morph (String s) {
int pos = s.lastIndexOf(".");
if (pos >= 0)
return s.substring(0,pos) + "!" + s.substring(pos+1);
return s;
}
public static void main(String args[]) {
System.out.println (morph("hello.world.how.are.you!"));
System.out.println (morph("no dots in here"));
System.out.println (morph(". first"));
System.out.println (morph("last ."));
}
}
The output is:
hello.world.how.are!you!
no dots in here
! first
last !
The regex you need is \\.(?=[^.]*$). the ?= is a lookahead assertion
"hello.world.how.are.you!".replace("\\.(?=[^.]*$)", "!")
Try this:
string = string.replaceAll("[.]$", "");
