PASSING DATA IN A JTable

[Kieran Murray]

Hi,

I started off this topic in two forums - yours and Sun forum.

View Topic @ https://coderanch.com/t/410463/java/java/Problems-passing-data-file-JTable

This caused some frustration and I then said that the Sun team should look at the question as I asked them first.

I think they gave up on me.

Your moderator suggested that I pass this topic to the intermediate team and I am doing so now. I will inform Sun that the topic on their site is moribund.

The problem is getting data out of an object. I have a JFrame and in that a JTabbedPane. In the JTabbedPane is a JTable. I pass the information from the JTable into the BusbarRecords class. I can not then access the information in this class when I come to save the file. How do I do this. When I instantiate the file in the main PowerFrame class the problem is I think that it instantiates a new object.

I include the code below for ease of reading. This is part of my MSC and I am getting desperate.

Main class PowerFrame

 
package tables;
 
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.Vector;
 
public class PowerFrame extends JFrame
{
 
private JFrame PowerFrame;
private JTabbedPane PowerTabPane;
 
private JMenuItem fMenuSave  = null;
 
JavaFilter fJavaFilter = new JavaFilter ();
File fFile = new File ("default.dat");
private Object v;
public Vector q;
private int count;
private int xcount;
private int qcount;
private int ycount;
private int pcount;
private File file;
 
BusbarRecords Busbar = new BusbarRecords();
BusbarsUI ui = new BusbarsUI();
 

public PowerFrame () {

super("Begin at the Beginning");
 
addWindowListener(new WindowAdapter() 
{ public void windowClosing(WindowEvent e)
{ System.exit(0);
}
 
});

PowerTabPane = new JTabbedPane(SwingConstants.RIGHT);
PowerTabPane.setBackground(Color.blue);
PowerTabPane.setForeground(Color.white);

populatePowerTabbedPane();
buildMenu();

getContentPane().add(PowerTabPane);

}

 

private void populatePowerTabbedPane()
{
PowerTabPane.addTab("Busbars", null, new BusbarsUI(), "Data for Busbar");


}
 
private void buildMenu()
{
JMenuBar mb = new JMenuBar();
JMenu menu = new JMenu("File");

    setJMenuBar (mb);
    setSize (400,400);
    
JMenuItem openitem = new JMenuItem("Open");
JMenuItem saveitem = new JMenuItem("Save");
JMenuItem exititem = new JMenuItem("Exit");

saveitem.addActionListener(new ActionListener()
{
 public void actionPerformed ( ActionEvent e ) {
    boolean status = false;
    status = saveFile ();
    if (!status)
        JOptionPane.showMessageDialog (
          null,
          "Error opening file!", "File Open Error",
          JOptionPane.ERROR_MESSAGE);
    }
 });


menu.add(saveitem);
 
mb.add(menu);
setJMenuBar(mb);
}
 

 

  
  boolean saveFile () {
     File file = null;
     JFileChooser fc = new JFileChooser ();
 
     // Start in current directory
     fc.setCurrentDirectory (new File ("."));
 
     // Set filter for Java source files.
     fc.setFileFilter (fJavaFilter);
 
     // Set to a default name for save.
     fc.setSelectedFile (fFile);
 
     // Open chooser dialog
     int result = fc.showSaveDialog (this);
 
     if (result == JFileChooser.CANCEL_OPTION) {
         return true;
     } else if (result == JFileChooser.APPROVE_OPTION) {
         fFile = fc.getSelectedFile ();
         if (fFile.exists ()) {
             int response = JOptionPane.showConfirmDialog (null,
               "Overwrite existing file?","Confirm Overwrite",
                JOptionPane.OK_CANCEL_OPTION,
                JOptionPane.QUESTION_MESSAGE);
             if (response == JOptionPane.CANCEL_OPTION) return false;
         }
         return getJTableFields(fFile);
     }
         else{
    return false;
         }

  } // saveFile


  
  public boolean getJTableFields(File file)
{
    String s = Busbar.getString();
    
 
         System.out.println(s);
     System.out.println("--------------------------");
     
    
 for(int i=0; i < 3;i++){
  for(int j=0;j < 5;j++)
  {
  /*System.out.println(model.getValueAt(i,j));*/
  }
 }
     
     try
 {
  FileOutputStream fos = new FileOutputStream(file);
  ObjectOutputStream object = new ObjectOutputStream(fos);
 /* object.writeObject(data2);*/
  object.flush();
  object.close();
 }
 catch(Exception ex)
 {
 System.out.println("Exception:" + ex);
 return false;
 }
return true;  
  }
  
   
 
public static void main(String[] args)
{
 
PowerFrame PF = new PowerFrame();
PF.pack();
PF.setSize(765,690);
PF.setBackground(Color.white);
PF.setVisible(true);

}
}

BusbarsUI class

 
package tables;
 

import javax.swing.JTable;
import javax.swing.JScrollPane;
import javax.swing.JPanel;
import javax.swing.event.TableModelEvent;
import javax.swing.event.TableModelListener;
import javax.swing.table.*;
 

import java.awt.*;
 
import java.util.*;
 
public class BusbarsUI extends JPanel implements TableModelListener{
   

    private int xcount;
    private int ycount;
   public String s;
   
    Vector rows;
    Vector columnNames;
    JTable table;
    
    
   
BusbarRecords Busbar=new BusbarRecords();

{

        }

    public BusbarsUI() {
    DefaultTableModel model = new DefaultTableModel();
    table = new JTable(model);
    for(xcount=1; xcount <= Busbar.ColumnNames.length; xcount++)
    {
    model.addColumn(Busbar.ColumnNames[xcount-1]);
    }
    model.addRow(Busbar.createBlankElement());
    model.addRow(Busbar.createBlankElement());
    model.addRow(Busbar.createBlankElement());
    Object[][] data = InitData();
    SetValues();
    model.addTableModelListener(this);
    setLayout(new BorderLayout());
    setBackground(Color.white);
    table.setPreferredScrollableViewportSize(table.getPreferredSize());
        JScrollPane scrollPane = new JScrollPane(table);
        
        add(scrollPane, BorderLayout.CENTER);
       
     
    }
    
    public Object[][] InitData()
    {
    TableModel model = table.getModel();
     Object[][] data = new Object[model.getRowCount()][Busbar.ColumnNames.length];
         for(xcount=1; xcount <= model.getRowCount(); xcount++)
         {
         for(ycount=1;ycount<=Busbar.ColumnNames.length;ycount++)
         data[xcount-1][ycount-1]="no";
         }
        return data; 
    }
    
    public void  SetValues(){
    
    TableModel model = table.getModel();
    Object[][] data1=InitData();
     for(xcount=1; xcount <= model.getRowCount(); xcount++)
         {
         for(ycount=1;ycount<=Busbar.ColumnNames.length;ycount++)
         model.setValueAt(data1[xcount-1][ycount-1],xcount-1,ycount-1);
         }
    }
    
       
public void tableChanged(TableModelEvent e)
{


 System.out.println(e.getSource());
 
if (e.getType() == TableModelEvent.UPDATE);

{
int row = e.getFirstRow();
int column = e.getColumn();
 
System.out.println(row);
System.out.println(column);
saveModel(row,column);
}
}
 

   public void saveModel(int row, int column)
   {  
  
TableModel model = table.getModel();


 String s =(String) model.getValueAt(row,column);
 BusbarRecords Busbar=new BusbarRecords(s);
System.out.println(s);

   }
   
 
  
   
 

 
   
}
 

BusbarRecords class

package tables;
 
import java.io.*;
 
import javax.swing.JTable;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
 
import java.util.Vector;
 
public class BusbarRecords implements Serializable
{

private String value;
private int row;
private int column;
private Object[][] data;
 
String[] ColumnNames = {"First Name", 
        "Last Name",
        "Sport",
        "# of Years",
        "Vegetarian"};
 
public BusbarRecords(String s)
{
getData(s);

}
 
public BusbarRecords()
{
 
}
 

 
public Vector createBlankElement()
{
Vector p = new Vector();
p.addElement((String) " ");
p.addElement((String) " ");
p.addElement((String) " ");
p.addElement((String) " ");
p.addElement((String) " ");
return p;
}
 
/*public void getData()
{
value="bob";

}*/
 
public void getData(String s)
{
value=s;
System.out.println(s + "New");

}
 

 
public String getString(){

return value;
}
 
}

JavaFilter class

 

package tables;
 
import javax.swing.*;
import java.io.*;
 
/** Filter to work with JFileChooser to select java file types. **/
public class JavaFilter extends javax.swing.filechooser.FileFilter
{
  public boolean accept (File f) {
    return f.getName ().toLowerCase ().endsWith (".java")
          || f.isDirectory ();
  }
 
  public String getDescription () {
    return "Java files (*.java)";
  }
} // class 
 

[Campbell Ritchie]

Sorry, I saw this last night and it was too late to reply.

I am afraid the app is too large just to read through and understand, so you will have to follow the execution with a debugger.

I suggest you get yourself a decent IDE, eg Eclipse, NetBeans, IntelliJ, and use the debugger.

Double-click the left side of the editor pane, where the line numbers go, and a blob will appear. This represents a breakpoint. Run the app from the IDE with run->debug, and when you get to the breakpoint it stops. You can open a "debug perspective" which allows you to see the objects and all their values throughout the whole app. I had to do the same with a much bigger MSc thing this time last year, and it isn't difficult once you get the hang of it.

Once you stop at the breakpoint, you have 3 options to go forward, which I think can be selected with the f5 f6 and f7 keys.

Step Into: follows the normal flow into method calls etc.

Step Over: Follows the flow but misses out details of method calls.

Step return: Goes to the end of the present method and back to where it was called from.

Careful with "step return;" it can go back too far and terminte the app if you aren't careful. I think they are called Step because they go one step at a time.

Don't know where to put the breakpoint, maybe in the actionPerformed method of the Listener on your save item.

Good luck with it, and we shall try to be more helpful than on the other site

[Campbell Ritchie]

Several weird things:

You are using .java as a filter, and creating a .dat file.

You are creating a new BusbarRecords object.

Your BusbarRecords constructor does not set up the initial state of an object. I think, maybe, you can't set up BusbarRecords correctly with a BusbarRecords(String) constructor at all.

Your saveFile() method which returns "true" from CANCEL_OPTION is odd. You would usually only use if (chooser.showSaveDialog(...) == JFileChooser.APPROVE_OPTION){...}

In your saveFile method, you are choosing a file, then setting the file to a different file.

After that, there doesn't seem to be any code which actually writes anything to the file.

You are using Vector rather than a more modern class, although that might be required by the constructor of one of the Components.

You are using Vector plain (raw) rather than Vector<BusbarSomethingOrOther>

You might also lose marks for inconsistent indenting conventions and capitalisation (it should be busbar rather than Busbar for the name of the object), and incorrect formatting for your comments.
Also if I were marking I would look askance as 1-indexed "for" loops. You should start with int i = 0;

Have you had any luck with the debugging?

Sorry I have got so many complaints, but it isn't my application and I am not quite sure what it is supposed to do. You would have made it easier for us (and probably picked up a few more marks) by adding more comments, particularly documentation comments.

[Rob Spoor]

Moving to AWT / Swing

[Kieran Murray]

Bob and Campbell,

Thank you for your time. The solution - and I found this by accident and I am not quite sure why is works is to make the String variable value in BusbarRecords static. Then it holds it value.

I can now get data into an array, save the array in a file and read back from the file.

My problem now is that the JTable will not update with the new data.

I will get back to you if I can not solve it.

Thanks again for your help.
In the immortal words of Buzz Lightyear "To infinity and beyond".

[Campbell Ritchie]

Very surprised at that.

Another weird thing I have found is your getValue() method which appears to act as a set method.