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C# 3.0:

对象初始化

从C# 3.0开始,初始化对象和集合都变得更加简单。以这个简单的Car类为例,我们可以使用前一节说到的自动属性。

class Car
{
    public string Name { get; set; }
    public Color Color { get; set; }
}

而在C# 2.0里面,我们可能需要写如下的一段代码来创建Car的一个实例并设置它的属性:

Car car = new Car();
car.Name = "Chevrolet Corvette";
car.Color = Color.Yellow;

这样也不错。但是换成C# 3.0,得益于新的对象初始化写法,它可以变得更简洁一点:

Car car = new Car { Name = "Chevrolet Corvette", Color = Color.Yellow };

如你看到的那样,我们在Car的一个新实例后面加了一对花括弧,在里面我们能处理Car类的所有public属性。这能少敲几次键盘,代码也短一点。而且它还是可以嵌套的。看看下面的例子,我们给Car类增加了一个复杂的新属性,像这样子:

class Car
{
    public string Name { get; set; }
    public Color Color { get; set; }
    public CarManufacturer Manufacturer { get; set; }
}

class CarManufacturer
{
    public string Name { get; set; }
    public string Country { get; set; }
}

用C# 2.0来初始化一个Car的新实例,我们得这样做:

Car car = new Car();
car.Name = "Corvette";
car.Color = Color.Yellow;
car.Manufacturer = new CarManufacturer();
car.Manufacturer.Name = "Chevrolet";
car.Manufacturer.Country = "USA";

用C# 3.0,我们可以变成这样:

Car car = new Car { 
                Name = "Chevrolet Corvette", 
                Color = Color.Yellow, 
                Manufacturer = new CarManufacturer { 
                    Name = "Chevrolet", 
                    Country = "USA" 
                } 
            };

你要是不太在乎可读性的话,还可以这样:

Car car = new Car { Name = "Chevrolet Corvette", Color = Color.Yellow, Manufacturer = new CarManufacturer { Name = "Chevrolet", Country = "USA" } };

和自动属性同样,这也是取决于你的偏好。你既可这么写,也可以按照老的传统方式来写。

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