Groovy def 和 Java Object 的区别？
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Difference between Groovy def and Java Object?
提问by Without Me It Just Aweso
I'm trying to figure out the difference between
我试图找出两者之间的区别
Groovy:
常规：
def name = "stephanie"
Java:
爪哇：
Object name = "stephanie"
as both seem to act as objects in that to interact with them i have to cast them to their original intended type.
由于两者似乎都充当与它们交互的对象，因此我必须将它们转换为原始预期类型。
I was originally on a search for a java equivalent of C#'s dynamic class ( Java equivalent to C# dynamic class type?) and it was suggested to look at Groovy's def
我最初是在搜索 C# 动态类的Java 等效项（Java 等效于 C# 动态类类型？），有人建议查看 Groovy 的def
for example my impression of groovy's def is that I could do the following:
例如，我对 groovy 的 def 的印象是我可以执行以下操作：
def DOB = new Date(1998,5,23);
int x = DOB.getYear();
however this wont build
但是这不会建立
thanks,steph
谢谢，斯蒂芬
Solution edit: Turns out the mistake iw as making is I had a groovy class wtih public properties (in my example above DOB) defined with def but then was attemping to access them from a .java class(in my example above calling .getYear() on it). Its a rookie mistake but the problem is once the object leaves a Groovy file it is simply treated as a Object. Thanks for all your help!
解决方案编辑：原来我犯的错误是我有一个带有公共属性的 groovy 类（在我上面的 DOB 示例中）用 def 定义，但随后试图从 .java 类访问它们（在我上面的示例中调用 .getYear( ） 在上面）。这是一个新手错误，但问题是一旦对象离开 Groovy 文件，它就会被简单地视为对象。感谢你的帮助！
回答by Erich Kitzmueller
Per se, there is not much difference between those two statements; but since Groovy is a dynamic language, you can write
就其本身而言，这两个陈述之间没有太大区别；但由于 Groovy 是一种动态语言，您可以编写
def name = "Stephanie"
println name.toUpperCase() // no cast required
while you would need an explicit cast in the Java version
而您需要在 Java 版本中进行显式转换
Object name = "Stephanie";
System.out.println(((String) name).toUpperCase());
For that reason, defmakes much more sense in Groovy than unfounded use of Objectin Java.
出于这个原因，def在 Groovy 中比Object在 Java 中毫无根据地使用更有意义。
回答by Przemyslaw
You can experiment with groovy in the groovy web console http://groovyconsole.appspot.com/
您可以在 groovy 网络控制台http://groovyconsole.appspot.com/ 中试验 groovy
Your initial groovy date example works.
您最初的常规日期示例有效。
