英文:
How can I make a protected static field public in sub class?
问题
我有这段代码：
class A {
protected static final String foo = "FOO";
}
class B extends A {
public static final String foo;
}
我期望 System.out.println(B.foo) 输出 FOO，但实际上输出了 null。
我知道可以通过在类 B 中将字段声明替换为方法来解决：
class B extends A {
public static final String foo() { return foo; }
}
是否可能继承受保护的静态字段并将其变为公共的？
类 B 被用作模拟对象，添加括号使调用变为 B.foo() 而不是 B.foo 并不重要，但我只是想知道是否有可能摆脱这些括号，如果是，是否有充分的理由不这样做。或者如果我的做法在某些方面完全错误。
英文:
I have this code:
class A {
protected static final String foo = "FOO";
}
class B extends A {
public static final String foo;
}
I expect System.out.println(B.foo) to print FOO but it prints null.
I know that I can get around this by replacing the field declaration in B with a method like:
class B extends A {
public static final String foo() { return foo; }
}
Is it possible to inherit a protected static field and make it public?
The class B is used as a mock object, and adding those parenthesis so the call is B.foo() instead of B.foo does not really matter, but I was just interested if it was possible to get rid of them, and if yes, if there is a good reason not to do that. Or if my approach is completely wrong in some other way.
答案1
得分: 3
我期望
System.out.println(B.foo)输出FOO，但实际上它输出了null。
这是因为 B.foo 没有重写 A.foo；相反，它遮蔽了 A.foo - 换句话说，B.foo 是一个新的变量，与 A.foo 分开，只是恰好具有相同的名称。
变量不能被重写，静态方法也不能被重写。
只有非静态方法可以在子类中被重写。
是否可能继承一个受保护的静态字段并将其变为公共的？
不可以。
英文:
> I expect System.out.println(B.foo) to print FOO but it prints null.
That is because B.foo does not override A.foo; instead, it shadows A.foo - in other words, B.foo is a new variable, separate from A.foo, that just happens to have the same name.
Variables cannot be overridden, and static methods cannot be overridden.
Only non-static methods can be overridden in a subclass.
> Is it possible to inherit a protected static field and make it public?
No.
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