java - 从正则表达式匹配器检索捕获组

Question

如何解析以下字符串中的两个数字:

String fName = "Run_1_vs_2_pw_optimal_mapping.txt";

我尝试了这样的方法，但不起作用:

    Pattern filePatt = Pattern.compile("Run_(\\d+)_vs_(\\d+)_", Pattern.CASE_INSENSITIVE);

    Matcher scanner = this.filePatt.matcher(fName);
    while (scanner.find()) {
            int groupSize = scanner.groupCount();
            if (groupSize == 2) {
                firstRun = Integer.parseInt(scanner.group(0));
                secondRun = Integer.parseInt(scanner.group(1));
            }
            break;
     }

但是，这不起作用，因为scanner.group(0) 返回Run_1_vs_2。但为什么呢？

Answer 1

参见the documentation .

Capturing groups are indexed from left to right, starting at one. Group zero denotes the entire pattern, so the expression m.group(0) is equivalent to m.group().

使用group(1)和group(2)。