java枚举类

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说明:

枚举类是一种特殊的数据类型

自定义枚举类:

package code06;

public class EnumClass01 {
    public static void main(String[] args) {
        Season spring = Season.SPRING;//获取自定义的枚举
        Season summer = Season.SUMMER;
        Season autumn = Season.AUTUMN;
        Season winter = Season.WINTER;

        System.out.println(spring);
        System.out.println(summer);
        System.out.println(autumn);
        System.out.println(winter);
    }

}

class Season {
    public String name;
    public String desc;
    public static Season SPRING = new Season("春天", "温暖");
    public static Season SUMMER = new Season("夏天", "酷热");
    public static Season AUTUMN = new Season("秋天", "凉爽");
    public static Season WINTER = new Season("冬天", "寒冷");

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

    }

    @Override
    public String toString() {
        return "Season{" +
                "name='" + name + '\'' +
                ", desc='" + desc + '\'' +
                '}';
    }
}
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打印结果

Season{name='春天', desc='温暖'}
Season{name='夏天', desc='酷热'}
Season{name='秋天', desc='凉爽'}
Season{name='冬天', desc='寒冷'}
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下面使用枚举类实现体验枚举类的简洁方便

package code06;

public class EnumClass01 {
    public static void main(String[] args) {
        Season spring = Season.SPRING;//直接.就可以使用
        Season summer = Season.SUMMER;
        Season autumn = Season.AUTUMN;
        Season winter = Season.WINTER;

        System.out.println(spring);
        System.out.println(summer);
        System.out.println(autumn);
        System.out.println(winter);
    }

}

enum Season {
    SPRING("春天", "温暖"),SUMMER("夏天", "酷热"),//多个枚举需要逗号区分
    AUTUMN("秋天", "凉爽"),WINTER("冬天", "寒冷");
    public String name;
    public String desc;

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

    }
 
    @Override
    public String toString() {
        return "Season{" +
                "name='" + name + '\'' +
                ", desc='" + desc + '\'' +
                '}';
    }


}

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细节

1.枚举类定义 通过 enum 加 名字
2.多个枚举通过逗号分割

enum其实是继承自Enum类
通过javap反编译我们可以进行分析

通过反编译我们可以看到 先是定义了四个枚举类型实例
并且该Seanson在内部使用final关键字其他类无法继承 Seanson继承自Enum类

枚举的常见几种方法

常用方法使用

package code06;

public class EnumClass01 {
    public static void main(String[] args) {
        Season spring = Season.SPRING;
        Season summer = Season.SUMMER;
        Season autumn = Season.AUTUMN;
        Season winter = Season.WINTER;

        System.out.println(spring.name());//打印出SPRING
        System.out.println(summer.ordinal());//输出枚举的顺序 从0开始 打印结果为1
        for (Season season:Season.values()){
            //如果你自己看我的反编译文件内容会发现里面有values方法
            System.out.println(season);//增强for循环 遍历枚举信息

            /*打印结果
            Season{name='春天', desc='温暖'}
            Season{name='夏天', desc='酷热'}
            Season{name='秋天', desc='凉爽'}
            Season{name='冬天', desc='寒冷'}
            * */
        }
        //也可以使用valueof获取值  前提必须有这个常量否则会报异常
        // 打印结果Season{name='秋天', desc='凉爽'}
        Season autumn1 = Season.valueOf("AUTUMN");
        System.out.println(autumn1);
        //比较两个编号 结果为 -1
        //解析  autumn编号为2 - winter编号3 所以结果为-1
        System.out.println(autumn.compareTo(winter));
    }

}

enum Season {
    SPRING("春天", "温暖"),SUMMER("夏天", "酷热"),
    AUTUMN("秋天", "凉爽"),WINTER("冬天", "寒冷");
    public String name;
    public String desc;

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

    }

    @Override
    public String toString() {
        return "Season{" +
                "name='" + name + '\'' +
                ", desc='" + desc + '\'' +
                '}';
    }


}

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