java Enum

1，定义常量

public enum WeekDay{
     SUN,MON,TUE,WED,THT,FRI,SAT
}

2，结合switch使用

public enum WeekDay{
    SUN,MON,TUE,WED,THT,FRI,SAT
}

public class SelectDay{
     WeekDay weekday=WeekDay.SUN;
     public void select(){
             switch(weekday){
                   case SUN:
                         weekday=WeekDay.SUN;
                         break;
                   ...
             }
     }
}

3，向枚举添加新方法

public enum Color{
      RED("红色",1),GREEN("绿色",2),WHITE("白色",3),YELLOW("黄色",4);
      //成员变量
      private String name;
      private int index;
      //构造方法
      private Color(String name,int index){
              this.name=name;
              this.index=index;
      }
      //普通方法
      public static String getName(int index){
           for(Color c:Color.values){
                 if(c.getIndex()==index){
                       return c.name;
                 } 
           }
           return null;
      }
      //get set 方法
      public String getName(){
            return name;
      }
      public void setName(String name){
            this.name=name;
      }
      public int getIndex(){
            return index;
      }
      public void setIndex(int index){
            this.index=index;
      }
}

4，覆盖枚举方法

public enum Color{
     RED("红色",1),GREEN("绿色",2),WHITE("白色",3),YELLOW("黄色",4);
     //成员变量
     private String name;
     private int index;
     //构造方法
     private Color(String name,int index){
           this.name=name;
           this.index=index;
     }
     //覆盖方法
     @Override
     public String toString(){
          return this.index+"_"+this.name;
     }
}

5，实现接口

public interface Behavior{
       void print();
       Striing getInfo();
}

public enum Color implements Behavior{
      RED("红色",1),GREEN("绿色",2),WHITE("白色",3),YELLOW("黄色",4);
      //成员变量
      private String name;
      private int index;
      //构造方法
      private Color(String name,int index){
            this.name=name;
            this.index=index;
      }
      //接口方法
      @Override
      public String getInfo(){
           return this.name;
      }
      @Override
      public void print(){
           System.out.println(this.index+":"+this.name);
      }
}

6，接口组织枚举

public interface Food{
      enum Coffe implements Food{
            BLACK_COFFEE,
            DECAF_COFFEE,
            LATTE,
            CAPPUCCINO;
      }
      enum Dessert implements Food{
            FRUIT,CAKE,GELATO;
      }
}

7，枚举集合

public class Test{
      public static void main(String[] args){
            EnumSet<WeekDay> week=EnumSet.noneOf(WeekDay.class);
            week.add(WeekDay.MON);
            System.out.println("EnumSet中的元素："+week);
            week.remove(WeekDay.MON);
            System.out.println("EnumSet中的元素："+week);
            week.addAll(EnumSet.complementOf(week));
            System.out.println("EnumSet中的元素："+week);
            week.removeAll(EnumSet.range(WeekDay.FRI,WeekDay.SAT));
            System.out.println("EnumSet中的元素："+week);
      }
}