Re: Serialization file getting bigger and bigger on the same object

yancheng.cheok@gmail.com wrote:


I ran your program as you posted it, and noted
the same effect you report, file size increasing
from an initial 8Kb, to 9.5, then 11.

Looking in the ser file, I noted a lot of cruft gets
serialised as well, so decided to try a run just
serializing the data.*

The size dropped to around 290-310 bytes (including
4 smallish values in the table data), but was still a little
'indefinite'.

Why not use XMLEncoder/Decoder instead?
The advantages are twofold.
- Serialization might well fail between class changes
(read as J2SE upgrades) - it is fragile.
- The XMLEncoder is optimized to store only what is
necessary, and will probably lead to a more predictable
file size.

* In any case, here is my variant that focuses on the
table data itself..

<sscce>
/*
* NewJFrame.java
*
* Created on April 8, 2007, 11:40 PM
*/

import java.io.*;
import javax.swing.table.*;
import java.util.Vector;

public class NewJFrame extends javax.swing.JFrame {

    Vector columnIdents;

   /** Creates new form NewJFrame */
   public NewJFrame() {
       initComponents();

       loadTableModel();
   }

   /** This method is called from within the constructor to
    * initialize the form.
    * WARNING: Do NOT modify this code. The content of this method is
    * always regenerated by the Form Editor.
    */
   // <editor-fold defaultstate="collapsed" desc=" Generated Code">
   private void initComponents() {
       jScrollPane1 = new javax.swing.JScrollPane();
       jTable1 = new javax.swing.JTable();
       columnIdents = new Vector();
       for (int ii=1; ii<5; ii++) {
           columnIdents.addElement(
               new String("Title " + (ii)));
       }
       Vector data = new Vector();
       for (int ii=1; ii<5; ii++) {
            data.add( new Vector(4) );
       }

setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
       addWindowListener(new java.awt.event.WindowAdapter() {
           public void windowClosed(java.awt.event.WindowEvent evt) {
               formWindowClosed(evt);
           }
       });

       jTable1.setModel(new javax.swing.table.DefaultTableModel(
           data, columnIdents
       ));
       jScrollPane1.setViewportView(jTable1);

       javax.swing.GroupLayout layout = new
javax.swing.GroupLayout(getContentPane());
       getContentPane().setLayout(layout);
       layout.setHorizontalGroup(

layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
           .addGroup(layout.createSequentialGroup()
               .addContainerGap()
               .addComponent(jScrollPane1,
javax.swing.GroupLayout.PREFERRED_SIZE, 375,
javax.swing.GroupLayout.PREFERRED_SIZE)
               .addContainerGap(15, Short.MAX_VALUE))
       );
       layout.setVerticalGroup(

layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
           .addGroup(layout.createSequentialGroup()
               .addComponent(jScrollPane1,
javax.swing.GroupLayout.PREFERRED_SIZE, 275,
javax.swing.GroupLayout.PREFERRED_SIZE)
               .addContainerGap(25, Short.MAX_VALUE))
       );
       pack();
   }// </editor-fold>

   private void formWindowClosed(java.awt.event.WindowEvent evt)
{
// TODO add your handling code here:
       saveTableModel();
       System.out.println("table model saved");
   }

   private boolean saveTableModel() {
        try {
           FileOutputStream fos = new
           FileOutputStream("table.ser", false);
           ObjectOutputStream out = new ObjectOutputStream(fos);
           out.writeObject(((DefaultTableModel)jTable1.
               getModel()).getDataVector());
           out.close();
       }
       catch(IOException exp) {
           exp.printStackTrace();
           return false;
       }

       return true;
   }

   private boolean loadTableModel() {
       //TableModel tableModel = null;
       Vector data = null;

       try {
           FileInputStream fos = new FileInputStream("table.ser");
           ObjectInputStream in = new ObjectInputStream(fos);
           //tableModel = (TableModel)in.readObject();
           data = (Vector)in.readObject();
           in.close();
       }
       catch(IOException exp) {
           exp.printStackTrace();
           return false;
       }
       catch(ClassNotFoundException exp) {
           exp.printStackTrace();
           return false;
       }

       //if(tableModel != null)
       if(data != null) {
           ((DefaultTableModel)jTable1.getModel()).
               setDataVector(data, columnIdents);
       }

       return true;
   }

   /**
    * @param args the command line arguments
    */
   public static void main(String args[]) {
       java.awt.EventQueue.invokeLater(new Runnable() {
           public void run() {
               new NewJFrame().setVisible(true);
           }
       });
   }

   // Variables declaration - do not modify
   private javax.swing.JScrollPane jScrollPane1;
   private javax.swing.JTable jTable1;
   // End of variables declaration

}
</sscce>

HTH

--
Andrew Thompson
http://www.athompson.info/andrew/

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