使用正则表达式查找2个括号之间的数字

Question

In a line I may have (123,456) I want to find it using pattern in java. What I did is:

Pattern pattern = Pattern.compile("\\W");
Matcher matcher = pattern.matcher("(");
while (matcher.find()) {
      System.out.print("Start index: " + matcher.start());
      System.out.print(" End index: " + matcher.end() + " ");
}

Input: This is test (123,456) Output: Start index: 0 End index: 1 ( Why??

Answer 1

I am not sure how \\W is going to match it. \\W matches a non word character.

You will also have to escape those backslashes.

Round brackets need to be escaped , as by default they are used for grouping.

Maybe the regex you meant was

Pattern pattern = Pattern.compile("\\([,\\d]+\\)");
Matcher matcher = pattern.matcher(inputString);

while (matcher.find()) {
    String matched = matcher.group();
    //Do something with it  
}

Explanation:

\\(     # Match (
[,\\d]+ # Match 1+ digits/commas. Don't be surprised if it matches (,,,,,,)
\\)     # Match )

Answer 2

一行完成：

String num = str.replaceAll(".*\\(([\\d,]+)\\).*", "$1");