Clojure throws ClassCastException on java.util.Collection
I'm trying to use an MPD library in Java in Clojure. Everything has gone well, but these methods that return a java.util.Collection
get bad reception in REPL. Let's define
(def mpd (org.bff.javampd.MPD. "localhost" ))
(def pl (.getMPDPlaylist mpd))
(def db (.getMPDDatabase mpd))
And now some methods play ok:
(.getSongList pl) ; returns List<MPDSong>
works well. But for instance every db
(MPDDatabase) method return Collection<MPDSong>
(according to their API):
(.findAlbum db "Crises") ; returns Collection<MPDSong>
java.lang.ClassCastException (NO_SOURCE_FILE:0)
Doesn't work that well. Why is that, how to fix it?
Stack trace follows:
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$fn__16.invoke(NO_SOURCE_FILE:1)
at clojure.lang.AFn.run(AFn.java:24)
at java.lang.Thread.run(Thread.java:662)
Caused by:开发者_运维技巧 java.lang.ClassCastException
at java.lang.Class.cast(Class.java:2990)
at clojure.lang.Reflector.boxArg(Reflector.java:364)
at clojure.lang.Reflector.boxArgs(Reflector.java:397)
at clojure.lang.Reflector.invokeMatchingMethod(Reflector.java:55)
at clojure.lang.Reflector.invokeInstanceMethod(Reflector.java:28)
at hello.hello$eval44.invoke(NO_SOURCE_FILE:8)
at clojure.lang.Compiler.eval(Compiler.java:5424)
... 9 more
nil
Looks like the API Documentation is invalid (checking using clojure.contrib.repl-utils):
user> (show MPDDatabase "findAlbum$")
=== public org.bff.javampd.MPDDatabase ===
[ 1] findAlbum : Collection (MPDAlbum)
and you need to a intermediate MPDAlbum object:
user> (.findAlbum db (MPDAlbum. "Crisis"))
#<ArrayList []>
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