java 基础 -- 枚举类的简介

骑猪看日落 2022-04-11 20:08 154阅读 0赞

### 自定义枚举类： ###

/**
     * @Date: 2018/12/3 11:18
     * @Description: 自定义枚举类
     */
    public class testEnum {
    
        public static void main(String args[]) {
    
            Season spring = Season.SPRING;
            System.out.println(spring);
    
        }
    }
    
    //自定义枚举类
    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
        private static final Season SPRING= new Season("spring","春暖花开");
        private static final Season SUMMER= new Season("summer","夏日炎炎");
        private static final Season AUTUMN= new Season("autumn","秋高气爽");
        private static final Season WINTER= new Season("winter","白雪皑皑");
    
    
        @Override
        public String toString() {
            return "Season{" +
                    "seasonName='" + seasonName + '\'' +
                    ", seasonDesc='" + seasonDesc + '\'' +
                    '}';
        }
    }

** 若枚举只有一个对象，则可以作为是一种单例模式的实现方式。**

### **使用enum  定义枚举类：** ###

/**
     * @Date: 2018/12/3 11:18
     * @Description:
     *  枚举类
     *  1.如何自定义枚举类
     *  2.如何使用enum 关键字定义枚举类
     *     > 常用的方法
     *     > 如何让枚举类实现接口
     *   values():将枚举类里面的所有的对象以数组的形式返回。
     *   valueof():传入string类型的参数，返回string的对象（返回枚举类的对象）
     */
    public class testEnum1 {
    
        public static void main(String args[]) {
    
            Season1 spring = Season1.SPRING;
            System.out.println(spring);
    
            spring.show();
    
            //1.values()
            Season1[] season1s = Season1.values();
            for (int i=0;i<season1s.length; i++){
                System.out.println(season1s[i]);
            }
    
            //2.valueof(String name):要求传入的形参name是枚举类对象的名字。
            //否则，报  java.lang.IllegalArgumentException 异常
            String str = "SPRING";
            Season1 season1 = Season1.valueOf(str);
            System.out.println(season1);
    
            Thread.State[] values = Thread.State.values();
            for (int i =0 ; i< values.length ; i++){
                System.out.println(values[i]);
            }
        }
    }
    
    interface Info{
        void show();
    }
    
    //自定义枚举类
    enum  Season1 implements Info{
    
        SPRING("spring","春暖花开"),
        SUMMER("summer","夏日炎炎"),
        AUTUMN("autumn","秋高气爽"),
        WINTER("winter","白雪皑皑");
    
    
        //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 Season1(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;
        }
    
        @Override
        public String toString() {
            return "Season{" +
                    "seasonName='" + seasonName + '\'' +
                    ", seasonDesc='" + seasonDesc + '\'' +
                    '}';
        }
    
        public void show(){
            System.out.println("123456789");
        }
    }

运行结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI4Mjg5NDA1_size_16_color_FFFFFF_t_70][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI4Mjg5NDA1_size_16_color_FFFFFF_t_70]: /images/20220412/e5a644ca6ea04af8bdd39c388cb6595a.png