01枚举类的定义和常见使用方法

01

如何自定义枚举类

• 1.jdk5.0之前 自定义枚举类
• 2.jdk5.0 可使用enum关键字定义枚举类

1.jdk5.0之前 自定义枚举类

package com.atguigu.java;

public class SeasonTest {
    public static void main(String[] args) {
        Season spring = Season.SPRING;
        System.out.println(spring);
    }
}

/**
 * 如何自定义枚举类
 * 1.jdk5.0之前 自定义枚举类
 * 2.jdk5.0 可使用enum关键字定义枚举类
 */
//jdk5.0之前 自定义枚举类
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,并给对象属性赋值
    public Season(String seasonName, String seasonDesc) {
        this.seasonName = seasonName;
        this.seasonDesc = seasonDesc;
    }

    //3.提供当前枚举类的多个对象：public static final的
    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.其他诉求1：获取枚举类对象的属性
    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }

    
    //4.其他诉求2：提供toString()
    @Override
    public String toString() {
        return "Season{" +
                "seasonName='" + seasonName + '\'' +
                ", seasonDesc='" + seasonDesc + '\'' +
                '}';
    }
}

2.使用enum关键字定义枚举类

1.多个对象之间使用逗号",“隔开。末尾”;"结束

2.默认继承于java.lang.Enum类

package com.atguigu.java;

public class SeasonTest1 {
    public static void main(String[] args) {
        Season1 summer = Season1.SUMMER;
        System.out.println(summer.toString());
        System.out.println(Season1.class.getSuperclass());
        // Season1{seasonName='夏天', seasonDesc='夏日炎炎'}

        System.out.println("****************");
        //values():返回所有的枚举类对象构成的数组
        Season1[] values = Season1.values();
        for(int i = 0;i < values.length;i++){
            System.out.println(values[i]);
            values[i].show();
        }
        System.out.println("****************");
        Thread.State[] values1 = Thread.State.values();
        for (int i = 0; i < values1.length; i++) {
            System.out.println(values1[i]);
        }

        //valueOf(String objName):返回枚举类中对象名是objName的对象。
        Season1 winter = Season1.valueOf("WINTER");
        //如果没有objName的枚举类对象，则抛异常：IllegalArgumentException
//        Season1 winter = Season1.valueOf("WINTER1");
        System.out.println(winter);
        winter.show();
    }

}

interface Info {
    void show();
}




//使用enum关键字定义枚举类
    //1.多个对象之间使用逗号","隔开。末尾";"结束
    //2.默认继承于java.lang.Enum类

enum Season1 implements Info {
    //先提供枚举类的对象
    SPRING("春天", "穿暖花开") {
        @Override
        public void show() {// 让枚举类的对象分别实现接口中的抽象方法
            System.out.println("春天在哪里？");
        }
    },
    SUMMER("夏天", "夏日炎炎") {
        @Override
        public void show() {
            System.out.println("宁夏");
        }
    },
    AUTUMN("秋天", "秋高气爽") {
        @Override
        public void show() {
            System.out.println("秋天不回来");
        }
    },
    WINTER("冬天", "冰天雪地") {
        @Override
        public void show() {
            System.out.println("大约在冬季");
        }
    };

    private final String seasonName;
    private final String seasonDesc;

    private Season1(String seasonName, String seasonDesc) {
        this.seasonName = seasonName;
        this.seasonDesc = seasonDesc;
    }

    //4.其他诉求1：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 "Season1{" +
                "seasonName='" + seasonName + '\'' +
                ", seasonDesc='" + seasonDesc + '\'' +
                '}';
    }
}

toString()

        Season1 summer = Season1.SUMMER;
        System.out.println(summer.toString());

values()

//values():返回所有的枚举类对象构成的数组
        Season1[] values = Season1.values();
        for(int i = 0;i < values.length;i++){
            System.out.println(values[i]);
            values[i].show();
        }

valueof()

 //valueOf(String objName):返回枚举类中对象名是objName的对象。
        Season1 winter = Season1.valueOf("WINTER");
        //如果没有objName的枚举类对象，则抛异常：IllegalArgumentException
//        Season1 winter = Season1.valueOf("WINTER1");
        System.out.println(winter);
        winter.show();
    }