>变量$1到$3 if
你使用String.replaceAll()或
> Matcher.group(n)如果您使用
Matcher.find()

有关详细信息,请参阅Pattern class的文档,尤其是Groups and Capturing.

示例代码：

final String needle = "abc(.*)def(.*)pqr(.*)xyz";
final String hayStack = "abcXdefYpqrZxyz";
 
// Use $variables in String.replaceAll()
System.out.println(hayStack.replaceAll(needle,"_$1_$2_$3_"));
// Output: _X_Y_Z_
 
 
// Use Matcher groups:
final Matcher matcher = Pattern.compile(needle).matcher(hayStack);
while(matcher.find()){
    System.out.println(
        "A: " + matcher.group(1) +
        ",B: " + matcher.group(2) +
        ",C: " + matcher.group(3)
    );
}
// Output: A: X,B: Y,C: Z