Add file filters to JavaFx Filechooser in Jython and parametrize them

Question

I created a javaFX chooser file in Jython. It wasn't easy to port from Java to Jython, but in the end some results came. Now I would like to parameterize the obtained class, taking into account the file filters, so as to be able to use the object for browsing different from the type of filtered files.
I tried to insert a fixed filter:

import sys

from javafx.application import Application
from javafx.stage import FileChooser, Stage

class fileBrowser(Application):

    @classmethod
    def main(cls, args):
        fileBrowser.launch(cls, args)

    def start(self, primaryStage):
        fc = FileChooser()
        filter = FileChooser.ExtensionFilter("All Images", '*.jpg')
        fc.getExtensionFilters().add(
            filter
        )

        f = fc.showOpenDialog(primaryStage)

if __name__ == '__main__':
    fileBrowser.main(sys.argv)

But I have the following error:

Exception in Application start method
Traceback (most recent call last):
  File "provaFileChooser.py", line 28, in <module>
    fileBrowser.main(sys.argv)
  File "provaFileChooser.py", line 15, in main
    fileBrowser.launch(cls, args)
        at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$1(LauncherImpl.java:182)
        at java.lang.Thread.run(Unknown Source)
Caused by: Traceback (most recent call last):
  File "provaFileChooser.py", line 19, in start
    filter = FileChooser.ExtensionFilter("JPG Images", '*.jpg')
TypeError: javafx.stage.FileChooser$ExtensionFilter(): 2nd arg can't be coerced to java.util.List, String[]

        at org.python.core.Py.TypeError(Py.java:236)
        at org.python.core.PyReflectedFunction.throwError(PyReflectedFunction.java:213)
        at org.python.core.PyReflectedFunction.throwBadArgError(PyReflectedFunction.java:316)
        at org.python.core.PyReflectedFunction.throwError(PyReflectedFunction.java:325)
java.lang.RuntimeException: java.lang.RuntimeException: Exception in Application start method

I also tried to cast the filter into a list and to insert the filter into a list but the error persists.

What am I doing wrong, and what should I do?
Thanks in advance.

Michelle Oliveira · Accepted Answer · 2020-10-23T15:11:48.310

You can solve your StackTrace using vector to parse the extension types, like this:

import sys

from java.io import File

from javafx.application import Application
from javafx.stage import FileChooser, Stage

class FileBrowser(Application):
    
    # I am a class attribute, Im called using NameClass.me
    # You have to remember this path is different according to SO
    initalDir = File("/home/miolivc/Documents/") # you have to handle this
    extensions = ["*.jpg"]

    @classmethod
    def main(cls, args):
        FileBrowser.launch(cls, args)

    def start(self, primaryStage):

        fc = FileChooser()
        filter = FileChooser.ExtensionFilter("All Images", FileBrowser.extensions)
        fc.getExtensionFilters().add(filter)
        fc.setInitialDirectory(FileBrowser.initalDir)

        choosed = fc.showOpenDialog(primaryStage)

        print("File: " + str(choosed))

if __name__ == '__main__':
    FileBrowser.main(sys.argv)

About using FileBrowser in others parts of your code, you have to understand how JavaFX works, you can use file in Controller class constructor and call this view using Scene class. FileBrowser is extending Application class, this mean that is the root of your app, you should call others from this one.

To understand more about this, I suggest you search about Scene and FXMLLoader.

I tested using Zulu Java FX 11 and Jython 2.7.1

Good morning Michelle! Sorry if I answer you late, but as you know the programmer's job is pretty lifeless! Thanks for your answer it was very comprehensive, but I would like to know 3 more things, if you tell me at least the first two, I'll give you what remains of the reward: 1) how to open the browser in a specific folder; 2) how to return the browsing file(s) to be used in other parts of the code; 3) how to put that filter list as a parameter of the class/methods. Thanks in advance! — Memmo, Oct 22 '20 at 09:45

Add file filters to JavaFx Filechooser in Jython and parametrize them

1 Answers1