枚举类

枚举类：就是对象的实例个数是确定的（例如：单例模式），也就说我们在创建枚举类的时候，会对构造器进行设置

一、自定义创建枚举类

package com.atguigu.java1;

public class TestSeason {
    public static void main(String[] args) {
        Season spring = Season.SPRING;
        System.out.println(spring);
        spring.show();
        System.out.println(spring.getSeasonName());
    }
}
//枚举类
class Season{
    //1.提供类的属性，声明为private final 
    private final String seasonName;
    private final String seasonDesc;
    //2.声明为final的属性，在构造器中初始化。
    private Season(String seasonName,String seasonDesc){
        this.seasonName = seasonName;
        this.seasonDesc = seasonDesc;
    }
    //3.通过公共的方法来调用属性
    public String getSeasonName() {
        return seasonName;
    }
    public String getSeasonDesc() {
        return seasonDesc;
    }
    //4.创建枚举类的对象:将类的对象声明public static final
    public static final Season SPRING = new Season("spring", "春暖花开");
    public static final Season SUMMER = new Season("summer", "夏日炎炎");
    public static final Season AUTUMN = new Season("autumn", "秋高气爽");
    public static final Season WINTER = new Season("winter", "白雪皑皑");
    @Override
    public String toString() {
        return "Season [seasonName=" + seasonName + ", seasonDesc="
                + seasonDesc + "]";
    }
    public void show(){
        System.out.println("这是一个季节");
    }
}

二、使用 enum 关键字创建枚举类

---

 （必须将生命的对象放在最前面，同时去掉重复的部分）并且之间用逗号隔开。其他与我们之前创建时一致的。

//枚举类
enum Season1{
    SPRING("spring", "春暖花开"),
    SUMMER("summer", "夏日炎炎"),
    AUTUMN("autumn", "秋高气爽"),
    WINTER("winter", "白雪皑皑");
    
    private final String seasonName;
    private final String seasonDesc;
    
    private Season1(String seasonName,String seasonDesc){
        this.seasonName = seasonName;
        this.seasonDesc = seasonDesc;
    }
    public String getSeasonName() {
        return seasonName;
    }
    public String getSeasonDesc() {
        return seasonDesc;
    }
    
    @Override
    public String toString() {
        return "Season [seasonName=" + seasonName + ", seasonDesc="
                + seasonDesc + "]";
    }
}

三、枚举类中主要使用的两个方法

  //1.values()：已数组的方式，获取所有的枚举成员
    Season1[] seasons = Season1.values();
    for(int i = 0;i < seasons.length;i++){
      System.out.println(seasons[i]);
    }
    //2.valueOf(String name):要求传入的形参name是枚举类对象的名字,获取枚举对象。
    //否则，报java.lang.IllegalArgumentException异常
    String str = "WINTER";
    Season1 sea = Season1.valueOf(str);

四、实现接口

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特殊之处在于，当每一对象需要单独实现 show 方法时，可以通过{}的形式，来完成需求。

interface Info{
    void show();
}
//枚举类
enum Season1 implements Info{
    SPRING("spring", "春暖花开"){
        public void show(){
            System.out.println("春天在哪里？");
        }
    },
    SUMMER("summer", "夏日炎炎"){
        public void show(){
            System.out.println("生如夏花");
        }
    },
    AUTUMN("autumn", "秋高气爽"){
        public void show(){
            System.out.println("秋天是用来分手的季节");
        }
    },
    WINTER("winter", "白雪皑皑"){
        public void show(){
            System.out.println("冬天里的一把火");
        }
    };