[英]How to pass list as a parameter to a clojure function
如何将list(collection)作为参数传递给clojure函数,此clojure由Java代码调用。
Clojure: Clojure的:
(ns utils ; Sets the namespace to utils
(:gen-class :name Utils ; The keyword :gen-class declares that
; I want this compiled as a class. The
; :name declares the name (and the package)
; of the class I want created.
:methods [#^{:static true} [sum [java.util.Collection] long]]))
; In the vector following :methods I've declared
; the methods I want to have available in the
; generated class. So I want the function 'sum'
; which takes a 'java.util.Collection' as an
; argument and returns a value of type 'long'.
; The metadata declaration '#^{:static true}
; signals that I want this method to be declared
; static.
; The Clojure function. Takes a collection and
; sums the values in the collection using 'reduce'
; and '+'.
(defn sum [coll] (reduce + coll))
; The wrapper function that is available to Java.
; Just calls 'sum'.
(defn -sum [coll] (sum coll))
Java: Java的:
public class CalculateSum {
public static void main(String[] args) {
java.util.List<Integer> xs = new java.util.ArrayList<Integer>();
xs.add(10);
xs.add(5);
System.out.println(Utils.sum(xs));
}
}
This prints out 15. 打印出15。
You might want to look at the great answers to the question on calling clojure from Java 您可能想看看有关从Java调用clojure的问题的绝佳答案
There's nothing special particularly about a list: any Java object can be passed as a parameter to a Clojure function in the same way. 列表没有什么特别的:可以使用相同的方式将任何Java对象作为参数传递给Clojure函数。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.