在groovy中从列表创建地图的快捷方式？ [英] shortcut for creating a Map from a List in groovy?

问题描述

 映射rowToMap（row）{
 def rowMap = [ ：]; 
 row.columns.each {rowMap [it.name] = it.val} 
 return rowMap; 
} 
  

给出GDK的东西，我希望能够做类似于：

 映射rowToMap（row）{
 row.columns.collectMap {[it.name，it .val]} 
} 
  

但我在文档中没有看到任何东西。 。我错过了什么？

解决方案

我最近遇到了需要做的事情：将列表转换为一张地图。这个问题发布在Groovy版本1.7.9之前，所以方法 collectEntries 尚不存在。它的工作原理与 collectMap 方法 ：

 映射rowToMap 
 row.columns.collectEntries {[it.name，it.val]} 
} 
  

$ b b

如果由于某种原因，您使用的是旧版本的Groovy，则 inject 方法（如在这里）。这是一个稍微修改的版本，只在闭包内只有一个表达式（只是为了节省字符！）：

  rowToMap（row）{
 row.columns.inject（[：]）{map，col  - > map<< [（col.name）：col.val]} 
} 
  

也可以使用$ c> + 运算符代替<< 。

I'd like some sorthand for this:

Map rowToMap(row) {
    def rowMap = [:];
    row.columns.each{ rowMap[it.name] = it.val }
    return rowMap;
}

given the way the GDK stuff is, I'd expect to be able to do something like:

Map rowToMap(row) {
    row.columns.collectMap{ [it.name,it.val] }
}

but I haven't seen anything in the docs... am I missing something? or am I just way too lazy?

解决方案

I've recently came across the need to do exactly that: converting a list into a map. This question was posted before Groovy version 1.7.9 came out, so the method collectEntries didn't exist yet. It works exactly as the collectMap method that was proposed:

Map rowToMap(row) {
    row.columns.collectEntries{[it.name, it.val]}
}

If for some reason you are stuck with an older Groovy version, the inject method can also be used (as proposed here). This is a slightly modified version that takes only one expression inside the closure (just for the sake of character saving!):

Map rowToMap(row) {
    row.columns.inject([:]) {map, col -> map << [(col.name): col.val]}
}

The + operator can also be used instead of the <<.

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