class FreshJuice {

  // 枚举：当做数据类型，只能接固定值（定义值）
   enum FreshJuiceSize{ 
    SMALL,
       MEDIUM, 
       LARGE 
    }FreshJuiceSize size;
  // size 是类FreshJuice的实体变量
}

public class FreshJuiceTest {

   public static void main(String args[]){

      FreshJuice juice = new FreshJuice();
      // 类.枚举名.枚举值
      juice.size = FreshJuice.FreshJuiceSize.MEDIUM;
      System.out.println("Size: " + juice.size);

      if (juice.size == FreshJuice.FreshJuiceSize.MEDIUM) {
        System.out.println("显示中杯页面");
      }else if (juice.size == FreshJuice.FreshJuiceSize.SMALL) {
        System.out.println("显示小杯页面");
      }else if (juice.size == FreshJuice.FreshJuiceSize.LARGE) {
        System.out.println("显示大杯页面");
      }
      
   }
}