java之枚举类型

1、介绍

package level2.myEnum;
import java.lang.Enum;




public class MyEnum {
    public static void main(String[] args) {
        System.out.println(Season.SPRING.showDescription());
        System.out.println(Season.SUMMER.showDescription());
        System.out.println(Season.AUTUMN.showDescription());
        System.out.println(Season.WINTER.showDescription());

        System.out.println(Season01.SPRING.showDescription());
        System.out.println(Season01.SUMMER.showDescription());
        System.out.println(Season01.AUTUMN.showDescription());
        System.out.println(Season01.WINTER.showDescription());
    }
}

// 1. 自定义枚举实现


class Season{

    private String name;
    private String description;

    public static final Season SPRING = new Season("春天", "温暖");
    public static final Season SUMMER = new Season("夏天", "炎热");
    public static final Season AUTUMN = new Season("秋天", "凉爽");
    public static final Season WINTER = new Season("冬天", "寒冷");

    public String showDescription(){
        return this.getName() + " " + this.getDescription();
    }

    private Season(String name, String description) {
        this.name = name;
        this.description = description;
    }

    public String getName() {
        return name;
    }

    public String getDescription() {
        return description;
    }

}

// 2、enum关键字实现枚举

enum Season01{

    // 使用enum实现枚举类
    // 1、public static final Season SPRING = new Season("春天", "温暖") 直接使用
    //    SPRING("春天", "温暖") --> 常量名(实参列表)
    // 2、如果有多个常量(对象), 用逗号 , 间隔
    // 3、如果使用enum实现枚举，要求将定义常量对象，写在最前边
    // 4、语句结束，使用 ; 号
    SPRING("春天", "温暖"),SUMMER("夏天", "炎热"),
    AUTUMN("秋天", "凉爽"),WINTER("冬天", "寒冷"),
    OTHER();    // 调用无参构造器

    private String name;
    private String description;

    public String showDescription(){
        return this.getName() + " " + this.getDescription();
    }

    private Season01() {
    }

    private Season01(String name, String description) {
        this.name = name;
        this.description = description;
    }

    public String getName() {
        return name;
    }

    public String getDescription() {
        return description;
    }

}

2、方法

package level2.myEnum;


public class EnumMethod {
    public static void main(String[] args) {
        Season02 summer = Season02.SUMMER;

        // 1. name：输出枚举对象的名称/引用名 (注意 不是构造器中的name参数)
        System.out.println(summer.name());

        // 2. ordinal：输出该枚举对象的次序/编号，编号从0开始
        System.out.println(summer.ordinal());

        // 3. values：返回一个数组，该数组含有所有定义的枚举对象
        Season02[] values = Season02.values();
        for(Season02 seasons:values){   // 依次从数组中取出元素，赋值给seasons，若已经取完，则退出for
            System.out.println(seasons);
        }

        // 4. valueOf：将字符串转换成枚举类型，要求字符串必须是已有的常量名，否则报异常
        //    根据输入的字符串 "SPRING" 到 Season02 的枚举对象中查找
        //    找到就返回对象，找不到就报错
        Season02 spring = Season02.valueOf("SPRING");
        System.out.println(spring);

        // 4. compareTo：比较两个枚举常量，比较的是对象的编号
        //    返回int: Season02.SUMMER编号 - Season02.WINTER编号
        System.out.println(Season02.SUMMER.compareTo(Season02.WINTER));
    }
}

enum Season02{

    SPRING("春天", "温暖"),SUMMER("夏天", "炎热"),
    AUTUMN("秋天", "凉爽"),WINTER("冬天", "寒冷");

    private String name;
    private String description;

    public String showDescription(){
        return this.getName() + " " + this.getDescription();
    }

    private Season02(String name, String description) {
        this.name = name;
        this.description = description;
    }

    public String getName() {
        return name;
    }

    public String getDescription() {
        return description;
    }

}