Implementing an image upload button using Jython & Swing

I'm developing a cross platform desktop application using Jython and Swing, and I found a hitch.
I would like to develop a button that allows me to load an image in its background and to change it when I reclick on the image loaded.

I attach as an example some pictures on how I would like my widget to be.

Upload pane without image

And then, when I load an image:

Upload Pane with image

I tried with the following code:

fd = FileDialog(self, "Scegli un'immagine", FileDialog.LOAD)
fd.setFile(';*.'.join(("*.bmp","jpg","jpeg","wbmp","png","gif")))
fd.setVisible(True)
fileName = fd.getFile()
if fileName != None :
    fileAbsPath = os.path.abspath(fileName)
    """'self.bigDict['imgButton']' is the current JButton"""
    self.bigDict['imgButton'].setIcon(ImageIcon(fileAbsPath))

When I click on "Open", the image is not inserted into the button. I do not understand why.
I also tried with the following code:

if fileName != None :
    fileAbsPath = os.path.abspath(fileName)
    img = ImageIO.read(getClass().getResource(fileAbsPath))
    self.bigDict['imgButton'].setIcon(img)

In the above example the following error is reported:

img = ImageIO.read(getClass().getResource(fileAbsPath))
TypeError: getClass(): expected 1 args; got 0

I would be curious to know why the button is not updated with the image loaded, and why the above error in java would not happen.

Thanks in advance!

Solution

The problem is very simple.
When an image is loaded with FileDialog it is "virtually located" in the FileDialog window, but the image does not exist. I realized this when I tried to copy the image from the absolute path to the destination folder, using shutil.copy2(self.imgAbsPath, destinationPath+'/'+self.imgName), which reported an error message indicating that the image does not exist.
To provide the concrete path of a file, it is necessary to add information about the folder where it is located.
In practice you have to create the relative path, before generating the absolute one:

fd = FileDialog(self, "Scegli un'immagine", FileDialog.LOAD)
fd.setFile(';*.'.join(("*.bmp","jpg","jpeg","wbmp","png","gif")))
fd.setVisible(True)
self.imgName = fd.getFile()
relativePath = fd.getDirectory() + fd.getFile() """Here is the missing piece!"""
if self.imgName != None:
   self.imgAbsPath = os.path.abspath(relativePath) """Here the absolute path is correctly obtained!"""
   self.bigDict['imgButton'].setIcon(ImageIcon(ImageIcon(self.imgAbsPath).getImage().getScaledInstance(130, 130, Image.SCALE_DEFAULT)))
   """The image, before being inserted into the button, is slightly resized, to avoid graphic bumps!"""

I hope I've been helpful.