没有公共类的.java文件的Java编译 [英] Java compilation of a .java file without a public class

问题描述

好的，所以java源文件必须至少有一个公共类，该文件应该被称为class-name.java。很公平。

Okay, so a java source file must have at least one public class and the file should be called "class-name.java". Fair enough.

因此，如果我有一个类，那么下面的代码将会编译：

Hence, if I have a class, then the following would compile:

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello World!"); // Display the string.
    }
}

但是，如果我删除'从上面的代码公共'访问修饰符，代码仍然编译。我只是不明白。删除它，代码如下：

But what bugs me is that if I remove the 'public' access modifier from the above code, the code still compiles. I just don't get it. Removing it, the code looks like:

class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello World!"); // Display the string.
    }
}

在上面的代码中，我删除了'public '访问修饰符，我的类有默认或包私有访问，即它不能从外部访问，只能从包内。

In the above code, since I removed the 'public' access modifier, my class has default or package private access, i.e. it can't be access from the outside world, only from within the package.

所以我的问题是，上面的代码如何编译？在这种情况下，文件HelloWorld.java没有'公共'HelloWorld类（只有一个包私有的HelloWorld.class），因此我的理解不应该编译。

So my question is, how does the above code compile ? The file HelloWorld.java in this case does not have a 'public' HelloWorld class (only a package-private HelloWorld.class) and thus to my understanding should not compile.

感谢您回答我的问题所花的时间！

Appreciate your time in answering my questions!

问候，
anon

regards, anon

推荐答案

一个java源文件必须至少有一个公共类，该文件应该被称为class-name.java

a java source file must have at least one public class and the file should be called class-name.java

不正确，顶级类不必声明为public。 JLS声明;

Incorrect, a top level class does not have to be declared public. The JLS states;

如果顶级类或接口类型未声明为public，则只能从包中访问它宣布它。

If a top level class or interface type is not declared public, then it may be accessed only from within the package in which it is declared.

参见 http://java.sun.com/docs/books/jls/second_edition/html/names.doc.html#104285 第6.6.1节。

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