java枚举enumeration java枚举根据value获取key

/**

* 测试枚举enum

*/

enum EnumSeason {

//enum默认extends java.lang.Enum 本质也是类

SPRING,SUMMER,AUTUMN,WINTER

//在枚举内创建常量 用,隔开 不赋值

}

enum EnumWeek{

MONDAY,TUESDAY,WEDNESDAY,THURSDAY,FRIDAY,SATURDAY,SUNDAY

//每个成员默认public static final修饰 常量

}

class TestEnum{

public static void main(String[] args) {

System.out.println(EnumSeason.SPRING);

//通过枚举名. 直接调用 结果为SPRING

System.out.println(Arrays.toString(EnumSeason.values()));

//枚举名.values()返回常量数组 数组的类型是Season[] 每一个元素都是Season的实例 结果[SPRING, SUMMER, AUTUMN, WINTER]

for (int i = 0; i< EnumSeason.values().length; i++){

System.out.println(EnumSeason.values()[i]);

}

for (EnumSeason s: EnumSeason.values()){

//for-each要输入对应的类型 .values()返回的是 Season[]数组 所以引用变量s也要用Season

System.out.println(s);

//常量本身不是字符串 enum重写了.toString 让常量打印自己的名字

}

int dayOfWeek = new Random().nextInt(EnumWeek.values().length);

switch (EnumWeek.values()[dayOfWeek]){

case MONDAY:

//不可以写EnumWeek.MONDAY

System.out.println(1);

break;

case TUESDAY:

System.out.println(2);

break;

case WEDNESDAY:

System.out.println(3);

break;

case THURSDAY:

System.out.println(4);

break;

case FRIDAY:

System.out.println(5);

break;

case SATURDAY:

System.out.println(6);

break;

case SUNDAY:

System.out.println(7);

break;

}

}

}