“无法降低继承方法的可见性”的含义有一个界面 [英] Meaning of "Cannot reduce the visibility of the inherited method" with an interface

问题描述

我有两个文件：

public interface PrintService {
    void print(PrintDetails details);
    class PrintDetails {
        private String printTemplate;
    }
    public interface Task {
        String ACTION = "print";
    }
}

和

public class A implements PrintService {
    void print(PrintDetails details) {
        System.out.println("printing: " + details);
    }
    String action = PrintService.Task.ACTION;   
}

我认为代码看起来还不错，但我在第二次收到错误该行的文件 void print（PrintDetails details）{表明：

I thought the code looks okay, but I am getting an error in the second file for the line void print(PrintDetails details) { that states:

不能从 PrintService 降低继承方法的可见性。

Cannot reduce the visibility of the inherited method from PrintService.

有人可以解释一下这对我意味着什么？

Can someone explain what this means for me?

推荐答案

在Java界面中，默认情况下每个方法都是 public ：

In a Java interface each method is by default public:

接口主体中的每个方法声明都是隐式抽象的，因此它的主体总是用分号表示，而不是一个块。

Every method declaration in the body of an interface is implicitly abstract, so its body is always represented by a semicolon, not a block.

接口主体中的每个方法声明都是隐式公共的。 [..]

Every method declaration in the body of an interface is implicitly public. [..]

在实施类中，不允许降低可见性，也不允许指定访问修饰符：

In an implementing class you are not allowed to reduce the visibility, and by not specifying an access modifier:

void print(){..}

您正在指定访问级别 默认 ，其可见度低于 public 。

you are specifying the access level default, which has lower visibility than public.

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