Why is this non-greedy regex grabbing more than I want?

Question

I would think this should return "state,country" but it's returning "country"

System.out.println("city,state,country".replaceAll("(.*,)?", ""));

Why is it working this way, and how do I make it return "state,country". I want this answer as a regex.

Answer 1

1. if you want to make .* to be non-greedy you need to add ? right after *.
2. replaceAll will replace all occurrences of matching parts, so you should probably use replaceFirst

try

System.out.println("city,state,country".replaceFirst(".*?,", ""));

output:

state,country

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If you can't use replaceFirst and need to stay with replaceAll then @Reimeus answer is probably what you are looking for.

Answer 2

As the name suggests, replaceAll replaces all matching groups. You need to be more specific where the group is matched. To specify the first matching group you can specify the start of String ^ as an anchor:

"city,state,country".replaceAll("^(.*?,)", "")

Answer 3

You're capturing any group ending in a comma, not just one and that's why it doesn't currently work.

System.out.println("city,state,country".replaceAll("^[^,]*+,", ""));

Answer 4

Try with this expression:

^(.*?,)

or like that:

System.out.println("city,state,country".replaceAll("(.*?,)((?:.*?,)+)", "$2"));

Answer 5

The ? non-greedy flag can only be used after a + or *, in your context, it is a 0-or-1 match.

You want

System.out.println("city,state,country".replaceAll("(.*?,)", ""));