Calling string.replaceAll() not working?

Question

public class MainWindow {
    public static void main(String[] args) {
        String s = "88,24";

        if(s.contains(",")){
            s.replaceAll(",", ".");
            System.out.println(s);
        }
    }
}

For the new application I'm working on I have to be able to replace a , with a . but I've had no success yet. Does anyone know of a way to do this?

`replaceAll` returns a new String. You have to use that one. — Murat Karagöz, May 08 '17 at 11:41
Remember, `String` are immutable, nothing can update it, even his own method don't update the instance — AxelH, May 08 '17 at 11:41
Your current issue aside, it looks like you are handling decimal values as strings. Don't do this. Treat them as decimals and only format the output where needed. — Filburt, May 08 '17 at 11:47
Just for the record: in case you feel inclined to, you can still accept answers, even on a closed question. — GhostCat, May 08 '17 at 12:01

GhostCat · Answer 1 · 2017-05-08T11:43:27.533

4

Strings are immutable. Their content can not be changed upon creation.

Therefore any method that changes the content of a String object will return that changed value to the Caller. No matter if you replace, concat, ...

Therefore you need

s = s.replace ...

to have the reference s point to that updated string value.

edited May 08 '17 at 11:43

answered May 08 '17 at 11:41

GhostCat

137,827
25
176
248

I would put more than italic on "changes" ;) – AxelH May 08 '17 at 11:42
1

Funny thing is that we have the same saying in french ;) so I get it ! – AxelH May 08 '17 at 11:49

score 1 · Answer 2 · answered May 08 '17 at 11:42

ReplaceAll is not inplace in nature. So,you have to explicitly assign it to s. Here is the code.

public class MainWindow {
    public static void main(String[] args) {
        String s = "88,24";

        if(s.contains(",")){
            s = s.replaceAll(",", ".");
            System.out.println(s);
        }
    }
}

Calling string.replaceAll() not working?

2 Answers2