java – 类声明中的成员接口是否隐含public？

发布时间：2020-12-14 16:42:47 所属栏目：Java 来源：网络整理

导读：码我有一个成员接口的类： package com.example.withinterface;public class SomeClass { interface SomeInterface { void doSomething(); }} 另一个试图访问它的课程： package com.example.withinterface.main;import com.example.withinterface.SomeClas

码

我有一个成员接口的类：

package com.example.withinterface;

public class SomeClass {

    interface SomeInterface {

        void doSomething();
    }
}

另一个试图访问它的课程：

package com.example.withinterface.main;

import com.example.withinterface.SomeClass;

public class Main {

    public static void main(String[] argss) {
        System.out.println(SomeClass.SomeInterface.class);
    }
}

错误

在Main中我从javac中得到以下错误：SomeClass中SomeInterface不是public;不能从外部包装访问.

在Eclipse中：SomeInterface在SomeClass中不是public;不能从外部包装访问.

两者都编译为Java 7.如果我将SomeInterface公开,那么所有的编译都很好.

但规格说

Java Language Specification for Java 7说：

A member interface is an interface whose declaration is directly
enclosed in another class or interface declaration.

A member interface in a class declaration is implicitly public (§6.6)
unless an access modifier is specified.

Java Language Specification for Java 5似乎没有第二句话.

题

那么不应该将SomeInterface视为公开的,不应该主要编译？

更新

如Ajay George所示,这的确是an error in the Java Language Specification 7(感谢JamesB).同时修改了规格,删除了错误的句子. Last version in Archive.org with the incorrect sentence.

解决方法

我猜这个规范是错的.
这是您的代码的javap输出.

E:workspace>javap comexamplewithinterfaceSomeClass
Warning: Binary file comexamplewithinterfaceSomeClass contains com.example.wi
thinterface.SomeClass
Compiled from "SomeClass.java"
public class com.example.withinterface.SomeClass {
  public com.example.withinterface.SomeClass();
}

E:workspace>javap comexamplewithinterfaceSomeClass$SomeInterface
Warning: Binary file comexamplewithinterfaceSomeClass$SomeInterface contains
com.example.withinterface.SomeClass$SomeInterface
Compiled from "SomeClass.java"
interface com.example.withinterface.SomeClass$SomeInterface {
  public abstract void doSomething();
}

我将界面更改为public,然后重新编译.

E:workspace>javap comexamplewithinterfaceSomeClass
Warning: Binary file comexamplewithinterfaceSomeClass contains com.example.wi
thinterface.SomeClass
Compiled from "SomeClass.java"
public class com.example.withinterface.SomeClass {
  public com.example.withinterface.SomeClass();
}

E:workspace>javap comexamplewithinterfaceSomeClass$SomeInterface
Warning: Binary file comexamplewithinterfaceSomeClass$SomeInterface contains
com.example.withinterface.SomeClass$SomeInterface
Compiled from "SomeClass.java"
public interface com.example.withinterface.SomeClass$SomeInterface {
  public abstract void doSomething();
}

注意内在类的差异.

（编辑：李大同）

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