Question

是否可以从私有类访问受保护的变量。是的会发生什么以及它是如何运作的？

private class classname{
    protected int variable_name = 5;
    private void method_name(){

         response.write(variable_name);

    }
}

在我的采访中提到了这个问题

Answer 1

是的，这是可能的，它意味着与正常情况完全相同：

public class Container
{
    private class Foo
    {
        protected int field;

        private class FurtherNested
        {
            // Valid: a nested class has access to all the members
            // of its containing class
            void CheckAccess(Foo foo)
            {
                int x = foo.field; 
            }
        }
    }

    private class Bar : Foo
    {
        void CheckAccess(Foo foo)
        {
            // Invalid - access to a protected member
            // must be through a reference of the accessing
            // type (or one derived from it). See
            // https://msdn.microsoft.com/en-us/library/bcd5672a.aspx
            int x = foo.field; 
        }

        void CheckAccess(Bar bar)
        {
            // Valid
            int x = bar.field;
        }
    }

    private class Baz
    {
        void CheckAccess(Foo foo)
        {
            // Invalid: this code isn't even in a class derived
            // from Foo
            int x = foo.field;
        }
    }
}

也就是说，从私有（因此嵌套）类型派生任何类型是相对不寻常的。

从私有类访问受保护的变量

1 个答案: