Question

I have a simple Jython GUI that displays an XML file in a JTree. Is there a method I can override in the tree model that will allow me to customize what the nodes in the JTree are called? Or do I need to do something with a renderer like Java? I’m looking for a Jythonic way to do this (as opposed to straight Java) if possible. I have access to Jython 2.5.0. My simple code looks like this:

from java import awt
from javax import swing
from java.lang import System
from xml.etree import ElementTree

class XmlTreeModel(swing.tree.TreeModel):
    def __init__(self, etree):
        self.etree = etree
    def getRoot(self):
        return self.etree.getroot()
    def getChildCount(self, object):
        return len(object)
    def getChild(self, parent, index):
        return parent[index]

class Viewer(swing.JFrame):
    def __init__(self):
        super(Viewer, self).__init__()
    def display(self, fileName):
        xmlObject = ElementTree.parse(fileName)
        xmlTreeModel = XmlTreeModel(xmlObject)
        jTree = swing.JTree(xmlTreeModel)
        self.contentPane.add(jTree)
        self.contentPane.setPreferredSize( awt.Dimension(100, 200) )        
        self.pack()
        self.setDefaultCloseOperation(swing.JFrame.EXIT_ON_CLOSE)
        self.setLocationRelativeTo(None)
        self.setVisible(True)

if __name__ == "__main__":
    viewer = Viewer()
    viewer.display('my.xml')

Right now the nodes appear as <Element Category at 2> and I’d like to change them to just say “Category” or even better, something custom from the XML attributes.

EDIT:
I was able to extend Chui Tey’s answer so that my tree displays an XML attribute by changing DisplayNode slightly:

class DisplayNode(object):
    def __init__(self, node):
        self.node = node
    def __repr__(self):
        return self.node.get('Name')
    def __getitem__(self, item):
        return self.node[item]
    def __len__(self):
        return len(self.node)

Instances of the class are then created with DisplayNode(self.etree.getroot()) and DisplayNode(parent[index]), respectively. For those of you arriving via search engine, this works for me because I know all of my XML nodes will have an attribute called Name.

Answer 1

JTree calls repr(node) on each xml node to get a string representation of what to display on the leaves of its tree.

You can override it by supplying your own repr method.

In the example below, I have set the value manually in the displaytext attribute.

from java import awt
from javax import swing
from java.lang import System
from xml.etree import ElementTree

class DisplayNode:
    def __init__(self, node, displaytext):
        self.node = node
        self.displaytext = displaytext
    def __repr__(self):
        return self.displaytext
    def __getitem__(self, item):
        return self.node[item]
    def __len__(self):
        return len(self.node)

class XmlTreeModel(swing.tree.TreeModel):
    def __init__(self, etree):
        self.etree = etree
    def getRoot(self):
        return DisplayNode(self.etree.getroot(), "Tree Root")
    def getChildCount(self, object):
        return len(object)
    def getChild(self, parent, index):
        return DisplayNode(parent[index], "Another Child")

class Viewer(swing.JFrame):
    def __init__(self):
        super(Viewer, self).__init__()
    def display(self, fileName):
        xmlObject = ElementTree.parse(fileName)
        xmlTreeModel = XmlTreeModel(xmlObject)
        jTree = swing.JTree(xmlTreeModel)
        self.contentPane.add(jTree)
        self.contentPane.setPreferredSize( awt.Dimension(100, 200) )        
        self.pack()
        self.setDefaultCloseOperation(swing.JFrame.EXIT_ON_CLOSE)
        self.setLocationRelativeTo(None)
        self.setVisible(True)

if __name__ == "__main__":
    viewer = Viewer()
    viewer.display('my.xml')