假设我有一个带有一些值的枚举类别:
enum Category {
ProgrammingBooks
CookingBooks
}
我希望每个枚举都有自己的枚举,例如: ProgrammingBooks将成立:
enum ProgrammingBooks {
CSharp,
Java,
Cpp
}
我看到了一个建议的解决方案:
enum Fauna {
enum Type { MAMMAL, BIRD }
TIGER(Type.MAMMAL),
LION(Type.MAMMAL),
PEACOCK(Type.BIRD),
OWL(Type.BIRD);
private final Type type;
Fauna(Type type) { this.type = type; }
}
用法:
Stream.of(Fauna.values()).filter(f -> f.type == BIRD).toList()
然而,我只是一个初学者,我寻找的东西即使我不知道也应该学习,不会对我说硬道理。我不明白我提到的例子(我在StackOverFlow上找到的)。
答案 0 :(得分:6)
使用类或接口。例如:
GridLayout
如果你想支持"子类型"您可以提供仅属于特定类而不属于界面的属性,因为并非每本书都与编程有关。例如:
public enum Category
{
ProgrammingBooks,
CookingBooks
}
public interface IBook
{
Category BookType { get; set; }
string Title { get; set; }
string Author { get; set; }
// ...
}
public class ProgrammingBook: IBook
{
public ProgrammingBook()
{
this.BookType = Category.ProgrammingBooks;
}
public string Author { get; set; }
public string Title { get; set; }
public Category BookType { get; set; }
// ...
}
public class CookBook : IBook
{
public CookBook()
{
this.BookType = Category.CookingBooks;
}
public string Author { get; set; }
public string Title { get; set; }
public Category BookType { get; set; }
// ...
}
为什么我要使用接口?因为所有书籍都有共同点(例如,它们都有标题和作者)。因此,您可以从Polymorphism:
中受益public enum ProgrammingLanguage
{
CSharp,
Java,
Cpp
}
public class ProgrammingBook: IBook
{
// a constructor that takes the ProgrammingLanguage as argument
public ProgrammingBook(ProgrammingLanguage language)
{
this.BookType = Category.ProgrammingBooks;
this.Language = language;
}
public ProgrammingLanguage Language { get; set; }
public string Author { get; set; }
public string Title { get; set; }
public Category BookType { get; set; }
// ...
}
或者如果您只想获得编程书籍:
var library = new List<IBook>();
var book1 = new ProgrammingBook(ProgrammingLanguage.CSharp) {Title = "C# in Depth", Author = "Jon Skeet"};
var book2 = new CookBook() { Title = "Everyday Superfood", Author= "Jamie Oliver" };
library.Add(book1);
library.Add(book2);
// now you can loop all and you know that all books have these properties
foreach (IBook book in library)
{
Console.WriteLine("Title: {0} Type: {1}", book.Title, book.BookType.ToString());
}
与LINQ的foreach (IBook book in library.Where(b => b.BookType == Category.ProgrammingBooks))
{
// ...
}
方法相同,只检查类型:
Enumerable.OfType
答案 1 :(得分:0)
枚举只是带有文本的整数的表示。它不能保存子类别或任何整数。
您应该为类别创建一个类,并在每个类别中保存子类别的枚举。
public class ProgrammingBook
{
public BookType Type{get;set;}
}
enum BookType {
CSharp,
Java,
Cpp
}