用逗号后跟空格替换逗号

Question

Due to the way server-side data is formatted I need to reformat it with my own function and to prevent any unwanted reformatting I want to check if the string I'm reformatting needs to be reformatted.

Here is the condition and the regex involved.

String value = "test, test, test.";

if (!value.matches("/(\\s*, )/g")) {
    return value.replaceAll(",", ", ");
}
else {
    return value;
}

The expected result is if a string is: Test,test,test it will reformat it to Test, test, test .

The behavior I am getting is that even the value string in the code goes into the if condition when it should skip it and go into the else .

Edit after consulting with my reviewer

The best solution found here for me was ",(?! )", ", " but it solved a problem I didn't even have so I simplified it to ",(\\\\S)", ", $1" .

The proposed solution would add a after , even if the , would be at the end of the string which is something I didn't want.

Also in my question, I had a redundant if condition which I removed and simplified the solution to:

String value = "Test,test,test";

return value.replaceAll(",(\\S)", ", $1");

Output:

Test, test, test

Answer 1

You don't need to check, you can just use :

value = value.replaceAll("\\s*,\\s*", ", ");

Input for example :

test ,   test, test.

Output

test, test, test.

Answer 2

You can use:

result = subject.replaceAll(",([^ ])", ", $1");

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Demo