一道面试题

import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
 * @author lawt
 * @date 2019/6/28
 */
public class IdCardTest {
    public static void main(String[] args) {
        // 测试是否为合法的身份证号码
        String[] idCards = {"140681199712092019", "13068119821209201X",
                "13068119871209201", "123456199112145", "123456199012245"};
        // 用于提取出生日字符串
        Pattern p2 = Pattern.compile("\\d{6}(\\d{8}).*");
        // 用于将生日字符串进行分解为年月日
        Pattern p3 = Pattern.compile("(\\d{4})(\\d{2})(\\d{2})");
        for (String idCard : idCards) {
            Matcher matcher = p2.matcher(idCard);
            boolean flag = matcher.find();
            if (flag) {
                String s = matcher.group(1);
                Matcher matcher2 = p3.matcher(s);
                if (matcher2.find()) {
                    System.out.println("生日:" + matcher2.group(1) + "年"
                            + matcher2.group(2) + "月"
                            + matcher2.group(3) + "日");
                }
            }
        }
    }
}

\d{17}[0-9a-zA-Z]|\d{14}[0-9a-zA-Z] 

[12][0-9]{3}[01][0-9][123][0-9] 

java.util.Regex