枚举类型的使用
如何使用枚举类：
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通常的方式是直接定义一个枚举类，但是如果想一个类定义多个枚举类，可以考虑将枚举类定义为内部类来实现例如：
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public class BabyConstants {public static final int BABY_SEX_BOY = 1;public static final int BABY_SEX_GIRL = 2;public static final int BABY_SEX_BOYANDGIRL = 3;public enum BabySex{BOY(1, "男"),GIRL(2, "女");BabySex(int value, String meaning) {this.value = value;this.meaning = meaning;}private final int value;private final String meaning;public int getValue() {return this.value;}public String getMeaning() {return this.meaning;}public static BabySex valueOf(int value) {for (BabySex e : BabySex.values()) {if (e.getValue() == value) {return e;}}return null;}}public enum Constellation{BAIYANGZUO(1, "白羊座"),JINNIUZUO(2, "金牛座"),SHUANGZIZUO(3, "双子座"),JUXIEZUO(4,"巨蟹座"),SHIZIZUO(5,"狮子座"),CHUNVZUO(6,"处女座"),TIANCHENGZUO(7,"天秤座"),TIANXIEZUO(8,"天蝎座"),SHESHOUZUO(9,"射手座"),MOJIEZUO(10,"魔羯座"),SHUIPINGZUO(11,"水瓶座"),SHUANGYUZUO(12,"双鱼座");Constellation(int value, String meaning) {this.value = value;this.meaning = meaning;}private final int value;private final String meaning;public int getValue() {return this.value;}public String getMeaning() {return this.meaning;}public static Constellation valueOf(int value) {for (Constellation e : Constellation.values()) {if (e.getValue() == value) {return e;}}return null;}}public enum Animal {SHU(1, "鼠"),NIU(2, "牛"),HU(3, "虎"),TU(4,"兔"),LONG(5,"龙"),SHE(6,"蛇"),MA(7,"马"),YANG(8,"羊"),HOU(9,"猴"),JI(10,"鸡"),GOU(11,"狗"),ZHU(12,"猪");Animal(int value, String meaning) {this.value = value;this.meaning = meaning;}private final int value;private final String meaning;public int getValue() {return this.value;}public String getMeaning() {return this.meaning;}public static Animal valueOf(int value) {for (Animal e : Animal.values()) {if (e.getValue() == value) {return e;}}return null;}}}?本段代码中既有不可变常量定义的性别，也有通过枚举定义的性别，就平时使用来说还是推荐使用枚举类型