java枚举类

枚举类的使用

 

1、枚举类的理解：类的对象只有有限个，确定的
2、当开发中需要定义一组常量时候，强烈建议使用枚举类
3、如果枚举类只有一个对象，则可以作为单例模式的实现方式

 

如何自动定义枚举类

方式一：jdk5之前，自定义枚举类

package com.jn.枚举;

/**
 * @author 江南大学1033190417
 * @date 2022/2/3 22:45
 *
 */
public class test01 {
    public static void main(String[] args) {
        System.out.println(Season.SPRING);
    }
}

class Season{
    private final String seasonName;
    private final String seasonDesc;

    //1、私有化构造器
    private Season(String seasonName,String seasonDesc){
        this.seasonName=seasonName;
        this.seasonDesc=seasonDesc;
    }

    //提供当前枚举类的多个对象
    public static final Season SPRING=new Season("春天","春暖花开");
    public static final Season SUMMER=new Season("夏天","夏日炎炎");
    public static final Season AUTUMN=new Season("秋天","秋高气爽");
    public static final Season WINTER=new Season("冬天","冰天雪地");

    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }

    @Override
    public String toString() {
        return this.seasonName;
    }

}

 

方式二：jdk5及其之后使用enum关键字

 

package com.jn.枚举;

/**
 * @author 江南大学1033190417
 * @date 2022/2/3 23:08
 */
public class test02 {
    public static void main(String[] args) {

        //几种常用方法
        //toString()
        System.out.println(Season1.SPRING);//SPRING
        System.out.println(Season1.class.getSuperclass());

        //values()
        Season1[] values = Season1.values();
        for (Season1 s:values){
            System.out.println(s);
        }

        //valueOf()
        Season1 winter = Season1.valueOf("WINTER");
        System.out.println(winter);//WINTER
    }
}

enum Season1{

    //提供当前枚举类的多个对象
    SPRING("春天","春暖花开"),
    SUMMER("夏天","夏日炎炎"),
    AUTUMN("秋天","秋高气爽"),
    WINTER("冬天","冰天雪地");


    private final String seasonName;
    private final String seasonDesc;

    //1、私有化构造器
    private Season1(String seasonName,String seasonDesc){
        this.seasonName=seasonName;
        this.seasonDesc=seasonDesc;
    }


    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }
}

 

 

 

诉求：是enum继承接口

例如

interface Info{
    void show();
}

enum Season1 implements Info{

 

只够重写show()方法

@Override
    public void show() {
        System.out.println("继承了Info接口");
    }

也可以具体情况具体而论

SPRING("春天","春暖花开"){
        @Override
        public void show() {
            System.out.println("春天在哪里");
        }
    },
    SUMMER("夏天","夏日炎炎"){
        @Override
        public void show() {
            System.out.println("夏天悄悄过去");
        }
    },
    AUTUMN("秋天","秋高气爽"){
        @Override
        public void show() {
            System.out.println("秋天在哪里");
        }
    },
    WINTER("冬天","冰天雪地"){
        @Override
        public void show() {
            System.out.println("冬天不回来");
        }
    };