Clojure在java.util.Collection上抛出ClassCastException

我想用一个 MPD library 在爪哇语中在Clojure。一切都很顺利,但是这些方法 java.util.Collection REPL接收不良。让我们来定义

(def mpd (org.bff.javampd.MPD. "localhost" ))
(def pl (.getMPDPlaylist mpd))
(def db (.getMPDDatabase mpd))

现在一些方法可以正常工作了:

(.getSongList pl) ; returns List<MPDSong>

效果很好。但举例来说 db (MPDDatabase)方法返回 Collection<MPDSong> (根据他们的API):

(.findAlbum db "Crises") ; returns Collection<MPDSong>
java.lang.ClassCastException (NO_SOURCE_FILE:0)

效果不太好。为什么,怎么解决?

堆栈跟踪如下:

hello.hello=> (.findAlbum db "Crises")
java.lang.ClassCastException (NO_SOURCE_FILE:0)
hello.hello=> (.printStackTrace *e)
java.lang.ClassCastException (NO_SOURCE_FILE:0)
    at clojure.lang.Compiler.eval(Compiler.java:5440)
    at clojure.lang.Compiler.eval(Compiler.java:5391)
    at clojure.core$eval.invoke(core.clj:2382)
    at clojure.main$repl$read_eval_print__5624.invoke(main.clj:183)
    at clojure.main$repl$fn__5629.invoke(main.clj:204)
    at clojure.main$repl.doInvoke(main.clj:204)
    at clojure.lang.RestFn.invoke(RestFn.java:422)
    at user$eval13$acc__808__auto____14$fn__16.invoke(NO_SOURCE_FILE:1)
    at clojure.lang.AFn.run(AFn.java:24)
    at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.ClassCastException
    at java.lang.Class.cast(Class.java:2990)
    at clojure.lang.Reflector.boxArg(Reflector.java:364)
    at clojure.lang.Reflector.boxArgs(Reflector.java:397)
    at clojure.lang.Reflector.invokeMatchingMethod(Reflector.java:55)
    at clojure.lang.Reflector.invokeInstanceMethod(Reflector.java:28)
    at hello.hello$eval44.invoke(NO_SOURCE_FILE:8)
    at clojure.lang.Compiler.eval(Compiler.java:5424)
    ... 9 more
nil