package HEX2;
public class RegExTest {
public static void main(String[] args) {
String str = "123456789.987654321";
String str2 = "123456789";
System.out.println(str.replaceAll("(?<=\d)(?=(\d{3})+[.])", ","));
System.out.println(str2.replaceAll("(?<=\d)(?=(\d{1})+$)", ","));
}
}
这两句输出里的正则表达式都怎么理解啊,求正则表达式很会的大神,给个详细的指导,解释下~谢谢了!!!