java 枚举（Enum）笔记

枚举

枚举类型是指由一组固定的常量组成合法的类型，由 enum 关键字来定义一个枚举类型。

定义

pulic enum Season{
    SPRING(1),SUMMER(2),AUTUMN(3),WINTER(4)
}

用法

1)switch

import java.lang.Enum;

enum Season{
    SPRING(1),SUMMER(2),AUTUMN(3),WINER(4);

    private int code;
    private Season (int code){
        this.code = code;
    }
    public int getCode(){
        return code;
    }
}

public class EnumDome01 {
    public String getChinesSeason(Season season){
        StringBuffer allSeasion = new StringBuffer();
        switch (season){
            case SPRING:
                allSeasion.append(season.name() + "SPRING对应的中国季节是春天，"+ "季节序号是" + season.getCode());
                break;
            case SUMMER:
                allSeasion.append(season.name() + "SUMMER对应的中国季节是夏天，"+ "季节序号是" + season.getCode());
                break;
            case AUTUMN:
                allSeasion.append(season.name() + "AUTUMN对应的中国季节是夏天，"+ "季节序号是" + season.getCode());
                break;
            case WINER:
                allSeasion.append(season.name() + "WINER对应的中国季节是夏天，"+ "季节序号是" + season.getCode());
                break;
            default:
                allSeasion.append("没有这个对应季节");
        }
        return allSeasion.toString();
    }

    public void doSamething(){
        for (Season str:Season.values()){
            System.out.println(getChinesSeason(str));

        }
    }
    public static void main(String[] args){
        EnumDome01 enum01 = new EnumDome01();
        enum01.doSamething();
    }
}

2)ordinal：返回枚举值在枚举类的顺序

Season.AUTUMN.ordinal();    //返回：2
Season.WINTER.ordinal();    //返回：3

3）compareTo()：比较对象的顺序

int s = Season.AUTUMN.compareTo(Season.WINER);

4)values()返回一个包含枚举全部数值的数组

Season[] allvalue = Season.values();

5）toString()：返回枚举常量的名称

6）equals()：比较两个枚举类对象的引用

7）TreeSet()：完成枚举排序操作

Set<Season> t = new TreeSet<Season>();
t.add(Season.SPRING);
t.add(Season.SUMMER);
t.add(Season.AUTUMN);
t.add(Season.WINTER);
Iterator it = t.iterator();
While(it.hasNaxt()){
    Season s = it.next();
    System.out.printl(s);

类集对枚举的支持

1）EnumMap

Map<Season,String> s = new EnumMap<Season,String>(Season.class);

2）EnumSet

EunmSet<Season> es = null;
es = EnumSet.allOf(Season.class);    //将枚举的全部类型设置到EnumSet对象中