Reputation: 10056
I have a string like s = "abc.def..ghi"
. I would like to replace the single'.' with two '.'s. However, s.replace(".", "..")
yields "abc..def....ghi". How can I get the correct behaviour? The output I'm looking for is s = "abc..def..ghi"
.
Upvotes: 5
Views: 220
Reputation: 425448
Use look arounds:
str = str.replaceAll("(?<!\\.)\\.(?!\\.)", "..")(
The regex reads as "a dot, not preceded by a dot, and not followed by a dot". This will handle the edge cases of a dot being at the start/end and/or surrounded by literally any other character.
Because look arounds don't consume input, you don't have to sully yourself with back references in the replacement term.
Upvotes: 2
Reputation: 2523
If you don't know how to do it using regex then use StringTokenizer
to split the String and again concatenate with ..
.
Code:
public static void main(String[] args) {
String s = "abc.def..ghi";
StringTokenizer s2 = new StringTokenizer(s, ".");
StringBuilder sb = new StringBuilder();
while(s2.hasMoreTokens())
{
sb.append(s2.nextToken().toString());
sb.append("..");
}
sb.replace(sb.length()-2, sb.length(), ""); // Just delete an extra .. at the end
System.out.println(sb.toString());
}
I know that the code is big compared to one line regex but I posted it in case if you are having any trouble with regex. If you think it is slower than the accepted answer, I did a start and end time with System.currentTimeMillis()
and I got mine faster. I don't know if there are any exceptions to that test.
Anyway, I hope it helps.
Upvotes: 3
Reputation: 73301
Replace the dot only when it's surrounded by two characters
String foo = s.replaceAll("(\\w)\\.(\\w)", "$1..$2");
Or as @Thilo commented, only if it's surrounded by two non dots
String foo = s.replaceAll("([^.])\\.([^.])", "$1..$2");
And to replace the single dot with two dots even if the dot is at the beginning/end of the string, use a negative lookahead and lookbehind:
(Example String: .abc.def..ghi.
will become ..abc..def..ghi..
)
String foo = s.replaceAll("(?<!\\.)\\.(?!\\.)", "..");
Upvotes: 6
Reputation: 97
s.replace("...","..");
s.replace("....","..");
Depends on input possibilities..
Upvotes: -6