Java正则表达式以和包含开头和结尾

Question

I have a file that I need to use regex to replace a specific character. I have strings of the following format:

1234 4215 "aaa.bbb" 5215 1524

and I need to replace the periods with colons. I know that these periods are always contained within quotation marks, so I need a regex that finds a substring that starts with '"', ends with '"', and contains "." and replace the "." with ":". Could someone shed some light?

Answer 1

You can use:

str = str.replaceAll("\\.(?!(([^"]*"){2})*[^"]*$)", ":");

RegEx Demo

This regex will find dots if those are inside double quotes by using a lookahead to make sure there are NOT even number of quotes after the dot.

Answer 2

Update

After thinking about it, your question says "period(s)" possibly more than one period in double quotes.

Here's a way to cover that scenario

public static void main(String[] args) throws Exception {
    String str = "1234 \"aaa.bbb\" \"a.aa.b.bb\" 5215 1524 \"12.345.123\" \".sage.\" \".afwe\" \"....\"";

    // Find all substrings in double quotes
    Matcher matcher = Pattern.compile("\"(.*?)\"").matcher(str);
    while (matcher.find()) {
        // Extract the match
        String match = matcher.group(1);

        // Replace all the periods with colons
        match = match.replaceAll("\\.", ":");

        // Replace the original matched group with the new string
        str = str.replace(matcher.group(1), match);
    }

    System.out.println(str);
}

Results:

1234 "aaa:bbb" "a:aa:b:bb" 5215 1524 "12:345:123" ":sage:" ":afwe" "::::"

And after testing @anubhava pattern, his produces the same results so more credit to him for simplicity (+1).

OLD ANSWER

You can try this pattern in a String.replaceAll()

"\"([^\\.]*?)(\\.)([^\\.]*?)\""

With a replacement of

"\"$1:$3\""

This essentially captures the contents, between double quotes, into groups (1-3).

• Group 1 ($1) - All characters, present or not (*?), that is not a period
• Group 2 ($2) - The period
• Group 3 ($3) - All characters, present or not (*?), that is not a period

and replaces it with "{Group 1}:{Group 3}"

public static void main(String[] args) throws Exception {
    String str = "1234 4215 \"aaa.bbb\" 5215 1524 \"12345.123\" \"sage.\" \".afwe\" \".\"";
    System.out.println(str.replaceAll("\"([^\\.]*?)(\\.)([^\\.]*?)\"", "\"$1:$3\""));
}

Results:

1234 4215 "aaa:bbb" 5215 1524 "12345:123" "sage:" ":afwe" ":"