Question

所以我第一次在C＃中使用Enumerations，但我不认为它会持久，因为我刚刚意识到你在Java中缺乏灵活性。

例如，我想用Java做的事情就像这样：

select products.id, data, name, count(sells.id) as sell_count
from products 
left join sells on sells.product_id=products.id 
where user= ?
group by products.id

无论如何我能在C＃中做到这一点吗？据我所知，使用枚举，您只能执行以下操作：

public enum Days {
    Mon("Monday"), Tue("Tuesday"), Wed("Wednesday"), Thu("Thursday", 93), Fri, Sat("Saturday", 44), Sun;

    private String longName;
    private int other;

    Days() {}
    Days(String longName) {
        this.longName = longName;
    }
    Day(String longName, int somethingElse) {
        this(longName);
        this.other = somethingElse;
    }

    @Override
    public String toString() {
        return this.longName + ", " + this.other;
    }
}

它不必严格地是枚举，就像Java枚举一样。

Answer 1

您可以在枚举中添加显示名称：

public class Days {

    private String longName;
    private int other;

    Days() {}
    Days(String longName) 
    {
        this.longName = longName;
    }
    Days(String longName, int somethingElse) 
        : this(longName) 
    {
        this.other = somethingElse;
    }

    public override String ToString() 
    {
        return this.longName + ", " + this.other;
    }

    // just an example - in reality you'd probably want to keep one instance for each property in a static dictionary.
    public static Days Mon {get{return new Days("Monday",1);}}
    public static Days Tue {get{return new Days("Tuesday",2);}}
    // etc.

}

但它只是元数据。你不能像Java（显然）那样在Java中添加实现。

你可以使用具有静态只读属性的类：

=$A11=0

但它与真正的＆＃34;之间存在显着差异。枚举。

Answer 2

public enum Days
{
    MON =1,
    TUE=2,
    WED=3,
    THUR=4,
    FRI=5,
    SAT=6,
    SUN=7
}

public static class EnumTypeExtensions
{
    public static string FriendlyString(this Days day)
    {
        switch (day)
        {
            case Days.MON:
                return "Monday";

C＃中的高级枚举

2 个答案: