Java中是否有C#风格的对象初始值设定项

Question

像这个吗http://weblogs.asp.net/dwahlin/archive/2007/09/09/c-3-0-features-object-initializers.aspx

Person p = new Person()
{
    FirstName = "John",
    LastName = "Doe",
    Address = new Address()
    {
        Street = "1234 St.",
        City = "Phoenix"
    }
};

Answer 1

在Java中，可以使用双括号初始化块执行类似的操作：

Person p = new Person() {{
    firstName = "John";
    lastName = "Doe";
    address = new Address() {{
        street = "1234 St.";
        city = "Phoenix";
    }};
}};

然而，这只是在匿名内部类中使用初始化块，因此效率低于以正常方式构造对象

Answer 2

事实上，有

Person p = new Person()
{{
    setFirstName("John");
    setLastName("Doe");
    setAddress(new Address()
    {{
        setStreet("1234 St.");
        setCity("Phoenix");
    }});
}};

甚至：

Person p = new Person()
{{
    firstName = "John";
    lastName = "Doe";
    address = new Address()
    {{
        street = "1234 St.";
        city = "Phoenix";
    }});
}};

这被称为双支架初始化。然而，我会避免使用这个习惯用法，因为它有一些意想不到的副作用，例如，这个语法实际上创建了一个匿名的内部类Person$1和Address$

另见

• What is Double Brace initialization in Java?
• Double Brace Initialization