Replacement needed by using replaceAll method

Question

I would like to get replaced string however I am unable to resolve which regex should be used.

Firstly I have many string like that;

String rawString = "w1.28-user_request"

Then , I want to get the string like that;

w1_28-user_request

As I said that, I have some string like that; week1.detailed_design so in that case I will have week1_detailed_design . Finally I just need to handle the case that w1.23_design_req-open

PS: user,request etc. are just a sample naming object

Please consider that, below usage is not useful for me because I have already had "." other than above case. For instance;

user.request_updated

So I just need to know how can I handle the case for this: w2.25-update_request

rawString.replaceAll("\\.","_"); // not useful

Finally, patterns are below;

• string1.2string should be string1_2string
• 1.2string should be 1_2string
• string1.2 should be string1_2

Answer 1

You need to replace a . enclosed with digits.

Use

rawString = rawString.replaceAll("(\\d)\\.(\\d)","$1_$2");

Pattern details :

• (\\\\d) - a digit captured into Group 1 (referred to via $1 from the replacement pattern)
• \\\\. - a literal dot
• (\\\\d) - a digit captured into Group 2 (referred to via $2 from the replacement pattern)

See the Java demo :

List<String> strs = Arrays.asList("string1.2string", "string1.2", "1.2string");
for (String str : strs)
    System.out.println(str.replaceAll("(\\d)\\.(\\d)", "$1_$2"));

Output:

string1_2string
string1_2
1_2string