Java: Some questions about JTree

decadent · 04-01-2004, 01:44 AM

First of all - sorry for my bad English.

There is tree with root "Towns" and leafs "Minsk", "Brest", "Grodno", "Vitebsk".

Code:

DefaultMutableTreeNode root = new DefaultMutableTreeNode("Towns");
DefaultMutableTreeNode child = new DefaultMutableTreeNode("Minsk"); root.add(child);
child = new DefaultMutableTreeNode("Brest"); root.add(child);
child = new DefaultMutableTreeNode("Grodno"); root.add(child);
child = new DefaultMutableTreeNode("Vitebsk"); root.add(child);

model = new DefaultTreeModel(root);
tree = new JTree(model);

There is button "x", if you press it, the name of current (selected) node and his parent will be printed.

Code:

JButton x = new JButton("x");
x.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent event) {
DefaultMutableTreeNode selectedNode = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();
System.out.println("Child:\n" + selectedNode + "\nParent:"+ selectedNode.getParent());
}});

How do set this values (name of current node and his parent) to the String variables.
I try write something like this: "String zxc = (String) (selectedNode.getParent());" but it does not work.

One more question.
How to interchange two neighbouring nodes?
For example, node "Grodno" is selected, I push "x" and "Grodno" now the second, and "Brest" - third.

Please, write code, if it is not difficult for you.

Komakino · 04-01-2004, 05:32 AM

You need to call getUserObject() on your tree node. For example, if you created you treenode with

Code:

DefaultMutableTreeNode node = new DefaultMutableTreeNode("England"); // just an example!

then to retrieve england you need to call:

Code:

String myString = (String)node.getUserObject();

because the treenode can hold any sort of user data object, so you need to cast it back to be a string.
What you have at the moment:

Code:

System.out.println("Child:\n" + selectedNode + "\nParent:"+ selectedNode.getParent());

Does not work because you're just printing the memory address of the parent node. What you should have is something like:

Code:

System.out.println("Child:\n" + (String)selectedNode.getUserObject() + "\nParent:"+ (String)(selectedNode.getParent()).getUserObject());