java - 为什么我们可以降低扩展类中属性的可见性？

Question

我有两个类，Parent:

public class Parent {
    public String a = "asd";

    public void method() {

    }
}

和 child :

public class Child extends Parent{
    private String a = "12";

    private void method() {

    }
}

在 Child 中，我尝试覆盖父级 method，它给出了编译时错误 cannot reduce visibility of a method 这很好.

但是，为什么这个错误不适用于属性 a？我还降低了 a 的可见性，但它没有给出错误。

Answer 1

这是因为Parent.a 和Child.a 是不同的东西。 Child#method() @Override Parent#method()，因为它们是方法。继承不适用于字段。

From the Oracle JavaTM Tutorials - Inheritance, it was written that:

What You Can Do in a Subclass

• The inherited fields can be used directly, just like any other fields.
• You can declare a field in the subclass with the same name as the one in the superclass, thus hiding it (not recommended).
• You can declare new fields in the subclass that are not in the superclass.