Java基础巩固系列 枚举（enum）

枚举类入门说明：

代码示例1：

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

//枚举类
class Season {
    //1.提供类的属性，声明为private final
    private final String seasonName;
    private final String seasonDesc;

    //2.声明为final的属性，在构造器中初始化。
    private Season(String seasonName, String seasonDesc) {
        this.seasonName = seasonName;
        this.seasonDesc = seasonDesc;
    }

    //3.通过公共的方法来调用属性
    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }

    //4.创建枚举类的对象:将类的对象声明 public static final
    public static final Season SPRING = new Season("Spring", "春暖花开");
    public static final Season SUMMER = new Season("Summer", "夏日炎炎");
    public static final Season FALL = new Season("Fall", "秋高气爽");
    public static final Season WINTER = new Season("Winter", "白雪皑皑");


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

    public void show() {
        System.out.println("这是一个季节");
    }
}

结果:

Season{seasonName='Spring', seasonDesc='春暖花开'}
这是一个季节
Spring

代码示例2：

/*
 * 一、枚举类
 * 1.如何自定义枚举类
 * 2.如何使用enum关键字定义枚举类
 *     > 常用方法:value() valueOf(String name)
 *     > 如何让枚举类实现接口:可以让不同的枚举类的对象调用被重写的抽象方法，执行的效果不同。（相当于让每个对象重写抽象方法）
 * */
public class TestSeason1 {
    public static void main(String[] args) {
        Season1 spring = Season1.SPRING;
        System.out.println(spring);
        spring.show();
        System.out.println(spring.getSeasonName());
        System.out.println();

        //1.value()
        Season1[] seasons = Season1.values();
        for (Season1 season : seasons) {
            System.out.println(season);
        }

        System.out.println();

        //2.valueOf(String name):要求传入的形参name是枚举类对象的名字。
        //否则，报java.lang.IllegalArgumentException异常
        String str = "WINTER";
        Season1 sea = Season1.valueOf(str);
        System.out.println(sea);
        sea.show();
        System.out.println();

        Thread.State[] states = Thread.State.values();
        for (int i = 0; i < states.length; i++) {
            System.out.println(states[i]);
        }
    }
}

interface Info{
    void show();
}

//枚举类
enum Season1 implements Info{
    SPRING("Spring", "春暖花开"){
        @Override
        public void show() {
            System.out.println("春天在哪里？");
        }
    },
    SUMMER("Summer", "夏日炎炎") {
        @Override
        public void show() {
            System.out.println("生如夏花");
        }
    },
    FALL("Fall", "秋高气爽") {
        @Override
        public void show() {
            System.out.println("秋天是用来分手的季节");
        }
    },
    WINTER("Winter", "白雪皑皑") {
        @Override
        public void show() {
            System.out.println("冬天里的一把火");
        }
    };

    private final String seasonName;
    private final String seasonDesc;

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

    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }


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

//    @Override
//    public void show() {
//        System.out.println("这是一个季节");
//    }
}

结果：

Season{seasonName='Spring', seasonDesc='春暖花开'}
春天在哪里？
Spring

Season{seasonName='Spring', seasonDesc='春暖花开'}
Season{seasonName='Summer', seasonDesc='夏日炎炎'}
Season{seasonName='Fall', seasonDesc='秋高气爽'}
Season{seasonName='Winter', seasonDesc='白雪皑皑'}

Season{seasonName='Winter', seasonDesc='白雪皑皑'}
冬天里的一把火

NEW
RUNNABLE
BLOCKED
WAITING
TIMED_WAITING
TERMINATED