Java

Question

出于某种原因，我无法将接口中的方法声明为仅包；它自动声明为 public。这是简化的代码：

package com.example.project;

public interface MyInterface {

    void foo();
    Thing bar(); // The class Thing is in the com.example.project package, but what it does isn't important.

}



package com.example.project;

public abstract class SimpleConcrete implements MyInterface { // Initializes all methods as hooks
    
    protected Thing bar = new Thing();
    
    void foo() {}
    Thing bar() { return bar }
    
}
    


package com.example.project;

public class ConcreteA extends SimpleConcrete {
    
    void bar() {
        // code here...
    }
    
}



package com.example.project;

public class ConcreteB extends SimpleConcrete {
    
    void bar() {
        // more code here...
    }
    
}

当我尝试编译它时，出现了这些错误，全部连接：

File: C:\ProjectFolder\com\example\project\SimpleConcrete.java [line: 7]

Error: Cannot reduce the visibility of the inherited method from me.mathmaniac.everworlds.Block

File: C:\ProjectFolder\com\example\project\ConcreteA.java [line: 3]

Error: The inherited method com.example.project.SimpleConcrete.foo() cannot hide the public abstract method in com.example.project.MyInterface

File: C:\ProjectFolder\com\example\project\ConcreteB.java [line: 3]

Error: The inherited method com.example.project.SimpleConcrete.foo() cannot hide the public abstract method in com.example.project.MyInterface

有谁知道如何解决这个问题，还是我必须将我的接口 public 保留到整个 Java 代码，而不仅仅是打开包？出于安全原因，我想只对包开放这些方法，但它需要，我会尝试找到其他方法来解决问题。

Answer 1

接口中声明的所有方法都是implicitly public。

All abstract, default, and static methods in an interface are implicitly public, so you can omit the public modifier.

要对方法使用任何其他访问修饰符，您必须将接口转换为 abstract class，并将方法转换为 abstract 方法。

Answer 2

Java 中接口内的所有方法都是隐式的 public。有关详细信息，请参阅此处：http://docs.oracle.com/javase/tutorial/java/IandI/interfaceDef.html

你可以这样声明接口包级别:

interface MyInterface {

    void foo();
    Thing bar();
}

这至少会将其封装在该包中。

Java - 继承方法com.example.project.ConcreteA不能隐藏抽象方法com.example.project.MyInterface

Java - the inherited method com.example.project.ConcreteA cannot hide the abstract method in com.example.project.MyInterface

inheritance

interface

access-modifiers