Java中的枚举（enum）

枚举的使用：

//枚举
enum Weekday
{
    SUNDAY,MONDAY,TUESDAY,WEDNESDAY,THURSDAY,FRIDAY,SATURDAY;
}

public class helloworld
{
    public static void main(String[] args)
    {
        System.out.println(Weekday.SUNDAY);//打印出SUNDAY,因为父类Enumo重写了toString方法
        
        Weekday[] days = Weekday.values();
        for(Weekday d : days)
        {
            System.out.println(d);
        }

        Weekday day = Weekday.valueOf("SATURDAY");
        switch(day)
        {
            case SUNDAY:
            case SATURDAY:
                System.out.println("周末");
                break;
            default:
                System.out.println("周一~周五");
                break;
        }
　　}
}

Weekday用Xjad反编译后为

final class Weekday extends Enum
{
    public static final Weekday SUNDAY;
    public static final Weekday MONDAY;
    public static final Weekday TUESDAY;
    public static final Weekday WEDNESDAY;
    public static final Weekday THURSDAY;
    public static final Weekday FRIDAY;
    public static final Weekday SATURDAY;
    private static final Weekday $VALUES[];

    public static Weekday[] values()
    {
        return (Weekday[])$VALUES.clone();
    }

    public static Weekday valueOf(String s)
    {
        return (Weekday)Enum.valueOf(Weekday, s);
    }

    private Weekday(String s, int i)
    {
        super(s, i);
    }

    static 
    {
        SUNDAY = new Weekday("SUNDAY", 0);
        MONDAY = new Weekday("MONDAY", 1);
        TUESDAY = new Weekday("TUESDAY", 2);
        WEDNESDAY = new Weekday("WEDNESDAY", 3);
        THURSDAY = new Weekday("THURSDAY", 4);
        FRIDAY = new Weekday("FRIDAY", 5);
        SATURDAY = new Weekday("SATURDAY", 6);
        $VALUES = (new Weekday[] {
            SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
        });
    }
}

 switch的一段，反编译为

        switch (1..SwitchMap.Weekday[weekday.ordinal()])
        {
        case 1: // '\001'
        case 2: // '\002'
            System.out.println("周末");
            break;

        default:
            System.out.println("周一~周五");
            break;
        }

可以认为，所有的enum的父类都是Enum类，Enum含有的方法

protected Enum(String name, int ordinal)
唯一的构造函数。
String name() 
返回此枚举常量的名称，与其枚举声明中声明的完全相同。  
int ordinal() 
返回此枚举常数的序数（其枚举声明中的位置，其中初始常数的序数为零）。  
String toString() 
返回声明中包含的此枚举常量的名称。  
boolean equals(Object other) 
如果指定的对象等于此枚举常量，则返回true。

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