Java - 无法导入com.package。*（通配符） [英] Java - Can't import com.package.*(wildcard)
问题描述
这可能是一个简单的问题，但Google没有返回任何内容。
This may be a simple issue, but Google has returned nothing.
I仍然不明白为什么直接导入会起作用但是通配符不会。
通过类包我的意思是一个类包。我还是Java新手所以我不知道语义
I still don't understand why a direct import will work but wildcard will not. By class package I mean a package of classes. I am still new to Java so I do not know the semantics
我有一个类包： com.company .functions ，当我尝试 import com.company。* 我收到以下错误。
I have a class package: com.company.functions, when I try to import com.company.* I receive the following error.
java: package com.company does not exist
如果我明确导入 com.company.function ，那么我没有任何问题。
If I import com.company.function explicitly then I have no issues.
所以我想我有一个解决方案，但为了学习，有人可以解释为什么我会看到这个问题吗？
So I suppose that I have a solution but for the sake of learning, could someone explain why I see this issue?
IDE：IntelliJ IDEA 12
IDE:IntelliJ IDEA 12
import com.sociapathy.*; <--Throws compile error java: package com.sociapathy does not exist
import com.sociapathy.databaseAccess.MySQL; <--Works just fine
推荐答案
听起来像你'尝试导入一个不包含类但只包含子包的包。
It sounds like you're trying to import a package that contains no classes, but only contains sub-packages.
ie您有 com.company.functions - 中的课程，例如 com.company.functions.Foo
但是没有类直接在 com.company - 例如 com.company.Bar
i.e. You have classes in com.company.functions - e.g. com.company.functions.Foo
But no classes directly in com.company - e.g. com.company.Bar
尽管java软件包似乎是分层的，但为了导入的目的，它们不是。
Despite that fact that java packages appear to be hierarchical, for the purposes of imports, they aren't.
因此，您无法导入 com.company。* ，因为它不包含自己的类。
您可以导入 com.company.functions。* 因为它确实包含类
您可以导入 com.company.functions.Foo 因为这是一个类。
So, you cannot import com.company.* because it contains no classes of its own.
You can import com.company.functions.* because it does contain classes
And you can import com.company.functions.Foo because that is a class.
现在，你可能会想要创建一个 Bar 类在 com.company 中。
这将允许您导入 com.company。*
但因为不会对层次结构进行处理，这不会导致 com.company.functions 中的类被导入
你仍然需要明确地导入 com。 company.functions.Foo ，或通配符导入 com.company.functions。*
Now, you might be tempted create a Bar class in com.company.
That would allow you to import com.company.*
But because imports are not treated hierarchically, that wouldn't cause classes in com.company.functions to be imported
You would still need to explictly import com.company.functions.Foo, or wildcard import com.company.functions.*
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