java @sign 有什么作用？
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What does the @sign do?
提问by Parham Doustdar
I have seen the at (@) sign in Groovy files and I don't know if it's a Groovy or Java thing. I have tried to search on Google, Bing, and DuckDuckGo for the mystery at sign, but I haven't found anything. Can anyone please give me a resource to know more about what this operator does?
我在 Groovy 文件中看到了 at (@) 符号，我不知道它是 Groovy 还是 Java 的东西。我曾尝试在 Google、Bing 和 DuckDuckGo 上搜索标志的神秘面纱，但我什么也没找到。任何人都可以给我一个资源来了解更多关于这个运营商做什么的信息吗？
采纳答案by Josh
It's a Java annotation. Read more at that link.
这是一个 Java注释。在该链接上阅读更多内容。
回答by tim_yates
As well as being a sign for an annotation, it's the Groovy Field operator
除了作为注释的标志外，它还是Groovy Field 运算符
In Groovy, calling object.fieldcalls the getFieldmethod (if one exists). If you actually want a direct reference to the field itself, you use @, ie:
在 Groovy 中，调用会object.field调用getField方法（如果存在）。如果您确实想要直接引用字段本身，请使用@，即：
class Test {
String name = 'tim'
String getName() {
"Name: $name"
}
}
def t = new Test()
println t.name // prints "Name: tim"
println t.@name // prints "tim"
回答by Rhysyngsun
It can also be used to access attributes when parsing XML using Groovy's XmlSlurper:
在使用 Groovy 的 XmlSlurper 解析 XML 时，它还可以用于访问属性：
def xml = '''<results><result index="1"/></results>'''
def results = new XmlSlurper().parseText(xml)
def index = results.result[0][email protected]() // prints "1"
http://groovy.codehaus.org/Reading+XML+using+Groovy's+XmlSlurper
http://groovy.codehaus.org/Reading+XML+using+Groovy's+XmlSlurper
回答by Hemant Metalia
'@' is an annotations in java/ Groovylook at the demo :Example with code
'@' 是 java/Groovy 中的一个注解看演示 : Example with code
Java 5 and above supports the use of annotations to include metadata within programs.Groovy 1.1 and above also supports such annotations.
Java 5 及更高版本支持使用注释在程序中包含元数据。Groovy 1.1 及更高版本也支持此类注释。
Annotations are used to provide information to tools and libraries.
They allow a declarative style of providing metadata information and allow it to be stored directly in the source code.
- Such information would need to otherwise be provided using non-declarative means or using external files.
注释用于为工具和库提供信息。
它们允许提供元数据信息的声明式风格，并允许它直接存储在源代码中。
- 否则需要使用非声明方式或使用外部文件提供此类信息。
