Clojure adding a border to a JPanel and in general accessing java methods in objects

Question

Coming from LISP I am having my most challenging moments when accessing java objects. I am trying to put a titled border on a JPanel. Here is my code and exception:

user=> (import '(javax.swing JComponent JPanel BorderFactory))
javax.swing.BorderFactory
user=> (JPanel. (.setBorder (.createTitledBorder "Title")))
#<CompilerException java.lang.IllegalArgumentException: No matching field found: createTitledBorder for class java.lang.String (NO_SOURCE_FILE:785)>

Where can I find rules to deal with this kind of situations? As always your help will be highly appreciated.

I thank you all for your answers and clarifications. I am posting the basics of the function so we can all know what to refer to:

(import '(javax.swing JComponent JButton JFrame JLabel JPanel BorderFactory))
(use '(clojure.contrib [miglayout :only (miglayout)]))

(defn cm_dlg []
  (let
    [
     panel_0
     (miglayout
       (JPanel.)
       :layout  [:wrap 2]
       (JLabel. "Some Text:") [:align "right"]
       (JLabel. "More Text:") [:align "left"]
       (JLabel. "Some Text:") [:align "right"]
       (JLabel. "More Text:") [:align "left"]
       (JLabel. "Some Text:") [:align "right"]
       (JLabel. "More Text:") [:align "left"]
       (JLabel. "Some Text:") [:align "right"]
       (JLabel. "More Text:") [:align "left"]
       )
     panel_1
     (miglayout 
       (JPanel.)
       :layout  [:wrap]
       (JButton. "Button0") [:align "center"]
       (JButton. "Button1") [:align "center"]
       (JButton. "Button2") [:align "center"]
       (JButton. "Button3") [:align "center"]
       )
     frame (JFrame. "Frame")
     ]
    (doto frame
      (.setDefaultCloseOperation JFrame/DISPOSE_ON_CLOSE)
      (-> .getContentPane
        (.add (miglayout (JPanel.)
                :layout [:flowy]
                panel_0 [:align "center"]
                panel_1 [:align "center"]
                )))
      (.pack)
      (.setVisible true))))

Like that the function works no problem but what I am trying to do is to put a TitledBorder on panel_0. Following your instructions I have tried to code in different ways but not success so far.
Thanks again to you all for your help.

UPDATE:Sorry googloplex. With all this mess I was running a different defn. Yes it works as you and Kugathasan said. I finally coded as:

....
   (JButton. "Button3") [:align "center"]
   )
     tb (BorderFactory/createTitledBorder "Title")
     frame (JFrame. "Frame")
     ]
    (.setBorder panel_0 tb)
    (doto frame
....

and IT WORKED !!! Thank you all for dedicating your time to this.

I hope you have got the answer. I would also suggest that you refer to `doto` macro which makes coding with Java objects quite easy and clean — Ankur, Dec 08 '11 at 04:29
FWIW, in Seesaw this is just `(mig-panel :border "Title" :items [...])`. — Dave Ray, Dec 08 '11 at 18:22

score 3 · Answer 1 · answered Dec 08 '11 at 02:35

3

You can try like this, the way you access Java in Clojure is wrong.

(.setBorder (JPanel.) (BorderFactory/createTitledBorder "Title"))

You may read java interop references to know how to access Java in Clojure..

answered Dec 08 '11 at 02:35

Abimaran Kugathasan

31,165
11
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105

I have this on a miglayout like so: (let [ panel0 (miglayout (JPanel.) (.setBorder (JPanel.) (BorderFactory/createTitledBorder "Title")) then the panel does not appear. – logigolf Dec 08 '11 at 03:10
I don't understand your logic, there are 2 `JPanel` objects in the code. – Abimaran Kugathasan Dec 08 '11 at 05:12
Thanks Kugathasan. The edited question that I have posted will give you a better idea where the TitledBorder should be implemented. – logigolf Dec 08 '11 at 16:58

Vladimir Matveev · Accepted Answer · 2011-12-08T17:42:59.060

Clojure language reference here gives the java interoperability rules pretty well. Here are the main points:

Static methods are called just like plain functions using class name as namespace:
```
(System/getProperty "java.class.path")
```
This will be resolved to java call System.getProperty("java.class.path")
Regular methods are called on specific objects of the class, so their calling syntax is slightly different:
```
(.setText label "Some text")
```
This will be resolved to java call label.setText("Some text"). That is, the regular method calls take this form:
```
(.methodName object arg1 arg2 arg3 ...)
```
Object are constructed using special form new:
```
(new JLabel "Initial text")
```
There is a shorthand for it using dot reader macro:
```
(JLabel. "Initial text")
```
These last two forms are completely equivalent. So, as you can see, construction takes this form:
```
(new Classname arg1 arg2 ...)
; or
(Classname. arg1 arg2 ...)
```

Of course, to use regular methods you have to bind newly created object to some symbol, e.g. like this:

(let [label (JLabel. "Initial text")]
  ...)

Inside let body you now can use label as an object:

(let [label (JLabel. "Initial text")]
  (.setText label "New text")
  (.setIconTextGap label 10))

As follows from your code in the commentary to Kugathasan Abimaran's answer, you are trying to use the same JPanel in several places. You are doing it incorrectly, since (see #3 above) (JPanel. ...) is a construction form, it returns new object every time you use it. You have to bind the new object to some variable, then call methods on it and then put it into container/whatever you need.

UPDATE: Your code is fine, you should do like Kugathasan Abimaran suggested. Add his code just before your (doto frame ... line, replacing (JPanel.) there with your panel_0. It will work as required.

Thanks googolplex that's very simple and explanatory. The edited question that I have posted will give you a better view of the environment where the TitledBorder should be applied. — logigolf, Dec 08 '11 at 16:57
By the way I coded <(.setBorder panel_0 BorderFactory/createTitledBorder "Title"))> before <(doto frame> but the border does not show. — logigolf, Dec 08 '11 at 19:43
This is not correct. You have to put `(BorderFactory/createTitledBorder "Title")` in parentheses for it to work. So complete line will be `(.setBorder panel_0 (BorderFactory/createTitledBorder "Test title"))`. It shows border for me. — Vladimir Matveev, Dec 08 '11 at 20:17

score 0 · Answer 3 · answered Dec 08 '11 at 01:32

0

What Java code are you trying to reproduce? It looks like you might want BorderFactory/createTitledBorder, but who knows?

answered Dec 08 '11 at 01:32

amalloy

89,153
8
140
205

Thanks for your quick answer amalloy. Yes. I've seen that as a way to be done in java, so that way or any one that puts that titled border on the panel. I am having particularly problems implementing those methods from java to clojure. Is there any rule of thumb that I can use? – logigolf Dec 08 '11 at 01:56

Clojure adding a border to a JPanel and in general accessing java methods in objects

3 Answers3