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目的
示例 Clojure 脚本说明了如何使用 GenericDialog 以及如何向用户显示信息。
该示例取自 Clojure 网站。
＃＃代码
;; Example taken from Clojure website
(import '(javax.swing JFrame JLabel JTextField JButton)
'(java.awt.event ActionListener)
'(java.awt GridLayout)
'(java.lang NumberFormatException))
; Define a function that does all, and which takes no arguments
(defn celsius []
; Define the gui elements as variables that point to new instances
; of buttons, labels, etc.
(let [frame (new JFrame "Celsius Converter")
temp-text (new JTextField)
celsius-label (new JLabel "Celsius")
convert-button (new JButton "Convert")
fahrenheit-label (new JLabel "Fahrenheit")]
; On the convert button, add an anonymous listener (proxy)
; In java it would be: button.addActionListener(new ActionListener() {
; public void actionPerformed(ActionEvent evt) { ... } } );
(. convert-button
(addActionListener
(proxy [ActionListener] []
(actionPerformed [evt]
; check that the entered string length is > 0
(let [snum (.getText temp-text)]
(if (> (.length snum) 0)
; check if the string is a number at all
(try (let [num (Double/parseDouble snum)]
(. fahrenheit-label
(setText (str (+ 32 (* 1.8 num)) " Fahrenheit"))))
(catch java.lang.NumberFormatException e
(. fahrenheit-label
(setText "Not a number"))))
; else, hint what is needed
(. fahrenheit-label
(setText "Enter a number"))))))))
; The number format error prevention could have been written by adding
; an extended PlainDocument to the JTextField which only accepts valid numbers.
; BUT one cannot call super, so the call to super.insertString() cannot be made!
; On the frame, call all the following methods
; It could be done with many blocks like (. frame (add celsius-label)) etc.
(doto frame
(.setLayout (new GridLayout 2 2 3 3))
(.add temp-text)
(.add celsius-label)
(.add convert-button)
(.add fahrenheit-label)
(.setSize 300 80)
(.setVisible true))))
; Execute the function
(celsius)
