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枚举类

一、自定义枚举类

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public class CustomEnumTest {
    public static void main(String[] args) {
        Season spring = Season.SPRING;
        System.out.println(spring);  // Season{seasonName='春天', seasonDesc='春天'}
    }
}

class Season {
    // 1. 声明Season对象的属性:private final 修饰
    private final String seasonName;
    private final String seasonDesc;

    // 2. 私有化类的构造器
    private Season(String seasonName, String seasonDesc){
        this.seasonName = seasonName;
        this.seasonDesc = seasonName;
    }

    // 3. 提供当前枚举类的多个对象 声明为public static final
    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");

    // 4.获取枚举类对象的属性
    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }

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

二、enum定义枚举类

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// 定义的枚举类默认继承于java.lang.Enum
public class enumTest {
    public static void main(String[] args) {
        Season spring = Season.SPRING;
        System.out.println(spring);  // SPRING
    }
}

enum Season {
    // 1. 提供当前枚举类的对象，多个对象直接用逗号，末尾用分号结束
    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");


    // 2. 声明Season对象的属性:private final 修饰
    private final String seasonName;
    private final String seasonDesc;

    // 3. 私有化类的构造器
    private Season(String seasonName, String seasonDesc) {
        this.seasonName = seasonName;
        this.seasonDesc = seasonName;
    }


    // 4.获取枚举类对象的属性
    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }
}

三、Enum类的主要方法

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/*
Enum类中的常用方法
valueOf(String str): 可以把一个字符串转为对应的枚举类对象，要求字符串必须是枚举类对象
*/
public class enumTest {
    public static void main(String[] args) {
        Season spring = Season.SPRING;

        // toString(): 返回当前枚举类对象常量的名称
        System.out.println(spring.toString());  // SPRING

        // values(): 返回枚举类型的对象数组，该方法可以很方便的遍历所有的枚举值
        Season[] values = Season.values();
        for (int i = 0; i < values.length; i++) {
            System.out.println(values[i]);
        }
        //        SPRING
        //        SUMMER
        //        AUTUMN
        //        WINTER

        // 返回枚举类中对象名是objName的对象，如果没找到则抛出IllegalArgumentException异常
        Season summer = Season.valueOf("SUMxMER");
        System.out.println(summer); // SUMMER
    }
}

enum Season {
    // 1. 提供当前枚举类的对象，多个对象直接用逗号，末尾用分号结束
    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");


    // 2. 声明Season对象的属性:private final 修饰
    private final String seasonName;
    private final String seasonDesc;

    // 3. 私有化类的构造器
    private Season(String seasonName, String seasonDesc) {
        this.seasonName = seasonName;
        this.seasonDesc = seasonName;
    }


    // 4.获取枚举类对象的属性
    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }
}

四、实现接口的枚举类

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/*
Enum类中的常用方法
valueOf(String str): 可以把一个字符串转为对应的枚举类对象，要求字符串必须是枚举类对象
*/
public class enumTest {
    public static void main(String[] args) {
        Season[] values = Season.values();
        for (int i = 0; i < values.length; i++) {
            values[i].show();
        }
        //        Hello SPRING
        //        Hello SUMMER
        //        Hello AUTUMN
        //        Hello WINTER
    }
}

interface Info {
    void show();
}

enum Season implements Info{
    // 1. 提供当前枚举类的对象，多个对象直接用逗号，末尾用分号结束
    SPRING("春天", "春暖花开"){
        @Override
        public void show() {
            System.out.println("Hello SPRING");
        }
    },
    SUMMER("夏天", "夏日炎炎"){
        @Override
        public void show() {
            System.out.println("Hello SUMMER");
        }
    },
    AUTUMN("秋天", "秋高气爽"){
        @Override
        public void show() {
            System.out.println("Hello AUTUMN");
        }
    },
    WINTER("冬天", "冰天雪地"){
        @Override
        public void show() {
            System.out.println("Hello WINTER");
        }
    };


    // 2. 声明Season对象的属性:private final 修饰
    private final String seasonName;
    private final String seasonDesc;

    // 3. 私有化类的构造器
    private Season(String seasonName, String seasonDesc) {
        this.seasonName = seasonName;
        this.seasonDesc = seasonName;
    }


    // 4.获取枚举类对象的属性
    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }

}