swing - Clojure 找不到方法 JComboBox.addItemListener

Question

希望这只是一个愚蠢的错误，但我看不到。

; OK
=> (filter (fn [x] (= "addItemListener" (.getName x))) (.getMethods javax.swing.JComboBox))
(#<Method public void javax.swing.JComboBox.addItemListener(java.awt.event.ItemListener)>)

; Error
=> (let [combobox (javax.swing.JComboBox. (java.util.Vector. ['a 'b 'c]))]
       (.addItemListener combobox
         (proxy [java.awt.event.ItemListener] []
           (itemStateChanged [item-event] (println (str "selection changed to " (.getSelectedItem combobox)))))
         combobox))
java.lang.IllegalArgumentException: No matching method found: addItemListener for class javax.swing.JComboBox (NO_SOURCE_FILE:0)

为什么clojure找不到addItemListener方法？

Answer 1

您第二次将组合框传递给 addItemListener 方法，您可能希望从 let 表单中返回它。

这应该有效：

(let [combobox (javax.swing.JComboBox. (java.util.Vector. ['a 'b 'c]))]
  (.addItemListener combobox
                    (proxy [java.awt.event.ItemListener] []
                      (itemStateChanged [item-event]
                        (println (str "selection changed to "
                                      (.getSelectedItem combobox))))))
  combobox)