Added method to get a file extension

project.clj

@@ -1,4 +1,4 @@
-(defproject org.ajoberstar/ike.cljj "0.3.0"
+(defproject org.ajoberstar/ike.cljj "0.4.0"
   :description "Clojure to Java interop APIs"
   :url "https://github.com/ajoberstar/ike.cljj"
   :license {:name "Eclipse Public License"

src/ike/cljj/file.clj

@@ -4,7 +4,8 @@
   (:refer-clojure :exclude [list])
   (:require [ike.cljj.stream :as stream]
             [ike.cljj.function :refer [defsam]]
-            [clojure.java.io :as io])
+            [clojure.java.io :as io]
+            [clojure.string :as str])
   (:import (java.nio.file Path Paths Files CopyOption LinkOption OpenOption StandardOpenOption FileVisitOption SimpleFileVisitor FileVisitResult)
            (java.nio.file.attribute FileAttribute)
            (java.nio.charset Charset StandardCharsets)
@@ -64,6 +65,14 @@
   (let [more-array (into-array String more)]
     (Paths/get x more-array)))
 
+(defn extension
+  "Gets the extension of the path, if any. Nil returned if there is no extension."
+  [path]
+  (let [name (-> path .getFileName str)
+        begin (str/last-index-of name ".")]
+    (when (and begin (< 0 begin) (< begin (dec (count name))))
+      (subs name (inc begin)))))
+
 (defn exists?
   "Tests whether the path exists."
   [path]

test/ike/cljj/file_test.clj

@@ -38,6 +38,12 @@
 (deftest path-accepts-multiple-args
   (is (instance? Path (file/path "/etc" "fstab"))))
 
+(deftest extension-test
+  (is (= "flac" (file/extension (file/path "/home" "person" "music.flac"))))
+  (is (= "conf" (file/extension (file/path ".music.conf"))))
+  (is (nil? (file/extension (file/path "/etc" "temp."))))
+  (is (nil? (file/extension (file/path "/var" "log" "app" "things")))))
+
 (deftest make-dir-test
   (let [path (.resolve (file/temp-dir "make-dir") "the-dir")]
     (is (not (file/exists? path)))