How to make an ArrayList in Clojure

arraylist, clojure, java

Solution

Use `doseq` instead of the lazy `for`. It has for-like bindings but it's meant for side-effects.

(defn make-an-array-list2 []
  (let [alist (java.util.ArrayList.)]
    (doseq [n (range 6)] (.add alist n)) alist))

;; [0 1 2 3 4 5]

Problem

I need to create and populate an ArrayList in clojure and pass it to an Java API. Can someone help explain why there is a difference in the below two approaches (and why one of them doesn't work). ``` ;;; this works (defn make-an-array-list [] (let [alist (java.util.ArrayList.)] (loop [x 0] (when (< x 6) (.add alist x) (recur (inc x)))) alist)) ;;; ==> [0 1 2 3 4 5] ;;; this does not work (defn make-an-array-list2 [] (let [alist (java.util.ArrayList.)] (for [n (range 6)] (.add alist n)) alist)) ;;; ==> [] ``` Or, any suggestion in stead of the above approach?

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