java 根据生日计算星座

public class ConstellationUtil {

public  enum Constellation {
Capricorn(1, "摩羯座"), Aquarius(2, "水瓶座"), Pisces(3, "双鱼座"), Aries(4,
"白羊座"), Taurus(5, "金牛座"), Gemini(6, "双子座"), Cancer(7, "巨蟹座"), Leo(
8, "狮子座"), Virgo(9, "处女座"), Libra(10, "天秤座"), Scorpio(11, "天蝎座"), Sagittarius(
12, "射手座");

private Constellation(int code, String chineseName) {
this.code = code;
this.chineseName = chineseName;
}
private int code;
private  String chineseName;

public int getCode() {
return this.code;
}
public String getChineseName() {
return this.chineseName;
}
}

public static final Constellation[] constellationArr = {
Constellation.Aquarius, Constellation.Pisces, Constellation.Aries,
Constellation.Taurus, Constellation.Gemini, Constellation.Cancer,
Constellation.Leo, Constellation.Virgo, Constellation.Libra,
Constellation.Scorpio, Constellation.Sagittarius,
Constellation.Capricorn
};

public static final int[] constellationEdgeDay = { 21, 20, 21, 21, 22, 22,
23, 24, 24, 24, 23, 22 };

public static String calculateConstellation(String birthday) {
if (birthday == null || birthday.trim().length() == 0)
throw new IllegalArgumentException("the birthday can not be null");
String[] birthdayElements = birthday.split("-");
if (birthdayElements.length != 3)
throw new IllegalArgumentException(
"the birthday form is not invalid");
int month = Integer.parseInt(birthdayElements[1]);
int day = Integer.parseInt(birthdayElements[2]);
if (month == 0 || day == 0 || month > 12)
return "";
month = day < constellationEdgeDay[month - 1] ? month - 1:month;
return month > 0 ? constellationArr[month - 1].getChineseName(): constellationArr[11].getChineseName();
}
}