写串代码从身份证号中提取身份证信息（IDInfo.java）。 编程要求 输入18位身份证号，输出性别、出生年月（格式为××××年××月××日）等信息。身份证号前四位代表所在城市，请判断所在城市。

以下是一个简单的实现：

import java.text.SimpleDateFormat;
import java.util.Date;

public class IDInfo {
    private static final String[] cityCodes = {
            "1101", "1201", "3101", "5001", "1301", "1401", "1501", "2101", "2201", "2301",
            "3100", "3201", "3301", "3401", "3501", "3601", "3701", "4101", "4201", "4301",
            "4401", "4501", "4601", "5000", "5101", "5201", "5301", "5401", "6101", "6201",
            "6301", "6401", "6501", "7101", "8101", "8201"
    };

    public static String getGender(String idNumber) {
        String gender = "";
        char c = idNumber.charAt(idNumber.length() - 2);
        if (c % 2 == 0) {
            gender = "女";
        } else {
            gender = "男";
        }
        return gender;
    }

    public static String getBirthday(String idNumber) {
        String birthday = "";
        String year = idNumber.substring(6, 10);
        String month = idNumber.substring(10, 12);
        String day = idNumber.substring(12, 14);
        birthday = year + "年" + month + "月" + day + "日";
        return birthday;
    }

    public static String getCity(String idNumber) {
        String city = "";
        String code = idNumber.substring(0, 4);
        for (int i = 0; i < cityCodes.length; i++) {
            if (code.equals(cityCodes[i])) {
                city = getCityName(i);
                break;
            }
        }
        return city;
    }

    private static String getCityName(int index) {
        String[] cityNames = {
                "北京市", "天津市", "上海市", "重庆市", "河北省", "山西省", "内蒙古自治区", "辽宁省", "吉林省", "黑龙江省",
                "上海市", "江苏省", "浙江省", "安徽省", "福建省", "江西省", "山东省", "河南省", "湖北省", "湖南省",
                "广东省", "广西壮族自治区", "海南省", "重庆市", "四川省", "贵州省", "云南省", "西藏自治区", "陕西省", "甘肃省",
                "青海省", "宁夏回族自治区", "新疆维吾尔自治区", "台湾省", "香港特别行政区", "澳门特别行政区"
        };
        return cityNames[index];
    }

    public static void main(String[] args) {
        String idNumber = "310101199001010011";
        String gender = getGender(idNumber);
        String birthday = getBirthday(idNumber);
        String city = getCity(idNumber);
        System.out.println("性别：" + gender);
        System.out.println("生日：" + birthday);
        System.out.println("城市：" + city);
    }
}

这个程序中，我们定义了三个静态方法 `getGender`、`getBirthday` 和 `getCity`，分别用于解析性别、出生日期和所在城市信息。在 `main` 方法中，我们演示了如何使用这三个方法来解析身份证号码信息。