import java.util.*; 和 import java.util.* 有什么区别？并导入 java.util.Date; ?
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What's the difference between import java.util.*; and import java.util.Date; ?
提问by EthanZ6174
I just want to output current and I wrote
我只想输出电流，我写了
import java.util.*;
at beginning, and
一开始，和
System.out.println(new Date());
in the main part.
在主要部分。
But what I got was something like this:
但我得到的是这样的：
Date@124bbbf
When I change the import to import java.util.Date;the code works perfectly, why?
当我将导入更改为import java.util.Date;代码工作正常时，为什么？
====================================
====================================
The problem was, OK, my source file was "Date.java", that's the cause.
问题是，好吧，我的源文件是“Date.java”，这就是原因。
Well, it is all my fault, I confused everybody around ;P
好吧，这都是我的错，我把周围的人都弄糊涂了;P
And thanks to everyone below. It's really NICE OF YOU ;)
并感谢下面的每一个人。你真的很好 ;)
采纳答案by sleske
You probably have some other "Date" class imported somewhere (or you have a Date class in you package, which does not need to be imported). With "import java.util.*" you are using the "other" Date. In this case it's best to explicitly specify java.util.Date in the code.
您可能在某处导入了其他一些“Date”类（或者您的包中有一个 Date 类，不需要导入）。使用“import java.util.*”，您使用的是“其他”日期。在这种情况下，最好在代码中明确指定 java.util.Date。
Or better, try to avoid naming your classes "Date".
或者更好的是，尽量避免将您的类命名为“日期”。
回答by cherouvim
Your program should work exactly the same with either import java.util.*;or import java.util.Date;. There has to be something else you did in between.
您的程序应该与import java.util.*;完全相同。或导入 java.util.Date; . 你必须在这两者之间做了一些其他的事情。
回答by Chris R
import java.util.*;
imports everything within java.util including the Date class.
导入 java.util 中的所有内容，包括 Date 类。
import java.util.Date;
just imports the Date class.
只导入 Date 类。
Doing either of these could not make any difference.
执行其中任何一个都没有任何区别。
回答by Vijay Dev
but what I got is something like this: Date@124bbbf
while I change the import to: import java.util.Date;
the code works perfectly, why?
What do you mean by "works perfectly"? The output of printing a Date object is the same no matter whether you imported java.util.* or java.util.Date. The output that you get when printing objects is the representation of the object by the toString() method of the corresponding class.
“完美运行”是什么意思？无论您导入 java.util.* 还是 java.util.Date，打印 Date 对象的输出都是相同的。打印对象时得到的输出是相应类的 toString() 方法对对象的表示。
回答by Fedearne
The toString()implementation of java.util.Datedoes not depend on the way the class is imported. It always returns a nice formatted date.
的toString()实现java.util.Date不依赖于类的导入方式。它总是返回一个很好的格式化日期。
The toString()you see comes from another class.
在toString()你看到来自另一个类。
Specific import have precedence over wildcard imports.
特定导入优先于通配符导入。
in this case
在这种情况下
import other.Date
import java.util.*
new Date();
refers to other.Dateand not java.util.Date.
指other.Date而不是java.util.Date。
The odd thing is that
奇怪的是
import other.*
import java.util.*
Should give you a compiler error stating that the reference to Date is ambiguous because both other.Dateand java.util.Datematches.
如果给你一个编译器错误，指出参考日期是模糊的，因为这两个other.Date和java.util.Date匹配。
