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saving (serializing) a complete tree structure of a JTree

Posted on 2001-06-06
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Last Modified: 2011-10-03
Hello Experts,

how can I serialize (save to a file) a complete tree structure of a Jtree ?

I used DefaultMutableTreeNodes.

The complete Tree has about 8000 nodes.

First I read the node informations from a text file, but this takes about 10 minutes, which is too long.

So I am looking for a possibility to save the complete JTree object or the nodes.

Best regards

F
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Question by:Fengler
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5 Comments
 
LVL 3

Expert Comment

by:chrisos
ID: 6160059
JTree implements the Serialisable interface so you should be able to do the following:

File outFile = new File("wherever");
FileOutputStream fos = new FileOutputStream(outFile);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(myJTree);

To load the tree back in you do:

File inFile = new File("wherever");
FileInputStream fis = new FileInputStream(inFile);
ObjectInputStream ois = new ObjectInputStream(fis);
myJTree = (JTree)oos.readObject();

Hope that helps,

Chrisos



0
 
LVL 4

Expert Comment

by:kylar
ID: 6160793
Ooo, Bad idea. You should never serialize Swing Objects, b/c they are not compatible with future versions. you should serialize the Tree Model instead.

Cheers,
Kylar
0
 
LVL 7

Accepted Solution

by:
Igor Bazarny earned 200 total points
ID: 6160863
Hi,

Here is the sample I made for someone at experts-exchange. It uses serialized model.


import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;

public class TreeDemo{
    public static void main(String[] args){
        DefaultTreeModel model = null;

        final File serFile = new File("TreeDemo.ser");

        if( serFile.exists() ){
            try{
                ObjectInputStream ois = new ObjectInputStream(new FileInputStream(serFile));
                model = (DefaultTreeModel)ois.readObject();
                ois.close();
            }
            catch(IOException err){
                err.printStackTrace();
            }
            catch(ClassNotFoundException err){
                err.printStackTrace();
            }
        }

        if(model == null){
            model = new DefaultTreeModel(new DefaultMutableTreeNode("root"));
        }

        final DefaultTreeModel innerModel = model;

        JFrame frame = new JFrame("Tree Demo");
        final JTree tree = new JTree(model);
        tree.setEditable(true);
        final JTextField editor = new JTextField();
        final Runnable activateEditor = new Runnable(){
            public void run(){
                editor.requestFocus();
                editor.setSelectionStart(0);
                editor.setSelectionEnd(editor.getText().length());
            }
        };

        tree.setCellEditor(new DefaultCellEditor(editor));
        frame.getContentPane().add(new JScrollPane(tree));
        tree.registerKeyboardAction( new ActionListener(){
            public void actionPerformed(ActionEvent event){
                TreePath path = tree.getLeadSelectionPath();
                if( path == null ){
                    return;
                }
                Object last = path.getLastPathComponent();
                if( !(last instanceof DefaultMutableTreeNode) ){
                    return;
                }
                DefaultMutableTreeNode node = (DefaultMutableTreeNode)last;
                DefaultMutableTreeNode newNode = new DefaultMutableTreeNode("New Node");
                innerModel.insertNodeInto(newNode,node,node.getChildCount());
                TreePath newPath = path.pathByAddingChild(newNode);
                tree.makeVisible(newPath);
                tree.startEditingAtPath(newPath);
                SwingUtilities.invokeLater(activateEditor);
            }
        },"Add Item",KeyStroke.getKeyStroke(KeyEvent.VK_INSERT,0),JComponent.WHEN_FOCUSED);

        tree.registerKeyboardAction( new ActionListener(){
            public void actionPerformed(ActionEvent event){
                TreePath path = tree.getLeadSelectionPath();
                if( path == null ){
                    return;
                }
                Object last = path.getLastPathComponent();
                if( !(last instanceof DefaultMutableTreeNode) ){
                    return;
                }
                DefaultMutableTreeNode node = (DefaultMutableTreeNode)last;
                innerModel.removeNodeFromParent(node);
            }
        },"Delete Item",KeyStroke.getKeyStroke(KeyEvent.VK_DELETE,0),JComponent.WHEN_FOCUSED);

        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.addWindowListener(new WindowAdapter(){
            public void windowClosed(WindowEvent event){
                try{
                    ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(serFile));
                    oos.writeObject(innerModel);
                    oos.close();
                }
                catch(IOException err){
                    err.printStackTrace();
                }
                System.exit(0);
            }
        });

        frame.pack();
        JButton modifyTest = new JButton("Modify Node");
        frame.getContentPane().add(modifyTest,BorderLayout.SOUTH);
        modifyTest.addActionListener( new ActionListener(){
            public void actionPerformed(ActionEvent event){
                TreePath path = tree.getLeadSelectionPath();
                Object last = path.getLastPathComponent();
                if( !(last instanceof DefaultMutableTreeNode) ){
                    return;
                }
                DefaultMutableTreeNode node = (DefaultMutableTreeNode)last;
                node.setUserObject((String)node.getUserObject()+"WWWWWWWWWW");
                innerModel.nodeChanged(node);
            }
        });
        frame.setVisible(true);
    }
}

Regards,
Igor Bazarny,
Brainbench MVP for Java 1
www.brainbench.com
0
 
LVL 1

Expert Comment

by:jimsims
ID: 6178491
the reason it is so slow is because each element likely has a reference to the tree, which causes a save of the whole tree for each element.

You should override the deafult serializer and walk the tree yourself, saving each node individually.

I had this same problem a few years back and eventually found this solution - went from 5 minutes to serialze a queue to 10 seconds, by serialing the queue myself and then serializing the ind objects
0
 
LVL 33

Expert Comment

by:sajuks
ID: 27290724
@bazarny..thanx a lot Sir..you really are a master:-)
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