java - 下面这句话 : 是什么意思

Question

来自this java API:

Dollar signs may be treated as references to captured subsequences as described above, and backslashes are used to escape literal characters in the replacement string.

我明白了第一点，但是对粗体下划线的部分有点困惑。 “转义文字字符”是什么意思？您会在替换字符串中转义哪种文字字符？

提前致谢。

Answer 1

好吧，$;)

public static void main(final String... args)
{
    final Pattern p = Pattern.compile("one dollar");

    final String input = "I want one dollar, please";

    // IndexOutOfBoundsException: no group 1
    System.out.println(p.matcher(input).replaceFirst("$1"));
    // You need to escape the "$"
    System.out.println(p.matcher(input).replaceFirst("\\$1"));
}