[英]Converting Clojure data structures to Java collections
What is the Clojure-idiomatic way to convert a data structure to a Java collection, specifically: 什么是将数据结构转换为Java集合的Clojure-idiomatic方法,具体为:
[]
to a java.util.ArrayList
[]
到java.util.ArrayList
{}
to a java.util.HashMap
{}
到java.util.HashMap
#{}
to a java.util.HashSet
#{}
到java.util.HashSet
()
to a java.util.LinkedList
()
到java.util.LinkedList
Is there a clojure.contrib library to do this? 是否有clojure.contrib库来执行此操作?
USE CASE : In order to ease Clojure into my organization, I am considering writing a unit-test suite for an all-Java REST server in Clojure. 使用案例 :为了使Clojure易于进入我的组织,我正在考虑为Clojure中的全Java REST服务器编写单元测试套件。 I have written part of the suite in Scala, but think that Clojure may be better because the macro support will reduce a lot of the boilerplate code (I need to test dozens of similar REST service calls).
我已经在Scala中编写了部分套件,但认为Clojure可能更好,因为宏支持将减少很多样板代码(我需要测试几十个类似的REST服务调用)。
I am using EasyMock to mock the database connections (is there a better way?) and my mocked methods need to return java.util.List<java.util.Map<String, Object>>
items (representing database row sets) to callers. 我使用EasyMock来模拟数据库连接(有更好的方法吗?),我的模拟方法需要将
java.util.List<java.util.Map<String, Object>>
项(代表数据库行集)返回给调用者。 I would pass in a [{ "first_name" "Joe" "last_name" "Smith" "date_of_birth" (date "1960-06-13") ... } ...]
structure to my mock and convert it to the required Java collection so that it can be returned to the caller in the expected format. 我会将
[{ "first_name" "Joe" "last_name" "Smith" "date_of_birth" (date "1960-06-13") ... } ...]
结构传递给我的模拟并将其转换为必需的Java集合,以便它可以以预期的格式返回给调用者。
Clojure vector, set and list classes implement the java.util.Collection
interface and ArrayList
, HashSet
and LinkedList
can take a java.util.Collection
constructor argument. Clojure向量,集合和列表类实现了
java.util.Collection
接口和ArrayList
, HashSet
和LinkedList
可以采用java.util.Collection
构造函数参数。 So you can simply do: 所以你可以简单地做:
user=> (java.util.ArrayList. [1 2 3])
#<ArrayList [1, 2, 3]>
user=> (.get (java.util.ArrayList. [1 2 3]) 0)
1
Similarly, Clojure map class implements java.util.Map
interface and HashMap
takes a java.util.Map
constructor argument. 同样,Clojure map类实现
java.util.Map
接口, HashMap
接受java.util.Map
构造函数参数。 So: 所以:
user=> (java.util.HashMap. {"a" 1 "b" 2})
#<HashMap {b=2, a=1}>
user=> (.get (java.util.HashMap. {"a" 1 "b" 2}) "a")
1
You can also do the reverse and it is much easier: 您也可以反过来做起来更容易:
ser=> (into [] (java.util.ArrayList. [1 2 3]))
[1 2 3]
user=> (into #{} (java.util.HashSet. #{1 2 3}))
#{1 2 3}
user=> (into '() (java.util.LinkedList. '(1 2 3)))
(3 2 1)
user=> (into {} (java.util.HashMap. {:a 1 :b 2}))
{:b 2, :a 1}
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