exception while creating JTables

[Karan Raj]

hi,
I am getting the following exception with my program.please chek this once.
------------------------------------------------------------
Exception in thread "main" java.lang.ClassCastException
at javax.swing.table.DefaultTableModel.justifyRows DefaultTableModel.jav
a:238)
at javax.swing.table.DefaultTableModel.setDataVector(DefaultTableModel.j
ava:194)
at javax.swing.table.DefaultTableModel.<init>(DefaultTableModel.java:131
)
at guidemo.<init>(guidemo.java:37)
at guidemo.main(guidemo.java:60)
----------------------------------------------------------------
i am tried to create a table with vectors.my code is as follows
code:-
-----
class guidemo extends JFrame{
private JTable data_tab;
private JLabel ptitle;
private Container c;
private Vector vdata;
private Vector vcolname;

public guidemo(){
super("EST Project Demo");
DefaultTableModel dtm;
c=getContentPane();
c.setLayout(null);
c.setSize(300,200);//intialising the contentpane

ptitle=new JLabel("EST project Details");
ptitle.setBounds(60,30,150,40);
c.add(ptitle);
setTableData();//intialising the vectors with some data
dtm=new DefaultTableModel(vdata,vcolname);
data_tab=new JTable(dtm);//setting table model
//data_tab.setPreferredScrollableViewportSize(new Dimension(500, 100));
c.add(data_tab);

WindowListener wndCloser = new WindowAdapter(){
public void windowClosing(WindowEvent e) {
System.exit(0);
}
};
addWindowListener(wndCloser);
setVisible(true);
}

public static void main(String[] args)
{
System.out.println("Hello World!");
setDefaultLookAndFeelDecorated(true);
new guidemo();
}

public void setTableData(){//intialise vectors with some data
vdata=new Vector();
vcolname=new Vector();
vdata.removeAllElements();
vdata.addElement(new dat("Eliuh",90,900,"uy89"));
vdata.addElement(new dat("Eryuh",920,900,"uy89"));
vdata.addElement(new dat("Elddh",940,900,"uy89"));
vdata.addElement(new dat("Elideu",90,900,"uy89"));
vdata.addElement(new dat("Elwciuh",760,900,"uy89"));
vdata.addElement(new dat("Elhhiuh",90,900,"uy89"));
vdata.addElement(new dat("Elicuh",100,900,"uy89"));
vdata.addElement(new dat("Eliuech",90,900,"uy89"));
vcolname.addElement(new cname("NAME","QStart","Qend","PID"));
}
}

class dat{
String name,gid;
int val,val2;
public dat(String n,int v,int v1,String g){
name=n;
val=v;
val2=v1;
gid=g;
}
}
class cname{
String s1,s2,s3,s4;
cname(String q, String w, String t, String y){
s1=q;
s2=w;
s3=t;
s4=y;
}
}
----------------------------------------------------------
I am not able to understand why i am getting that exception.if any body have solution for my problem it will be greatly helpful for me.
thanks,
karan

[Vijay]

I have got rid of the bug in ur code. The following code should compile.
KRR

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
import java.util.*;
class guidemo extends JFrame
{
    private JTable data_tab;
    private JLabel ptitle;
    private Container c;
    private Vector vdata;
    private Vector vcolname;

    public guidemo()
    {
        super("EST Project Demo");
        DefaultTableModel dtm;
        c=getContentPane();
        c.setLayout(null);
        //c.setSize(500,500);//intialising the contentpane
        ptitle=new JLabel("EST project Details");
        ptitle.setBounds(60,30,150,40);
        c.add(ptitle); 
        setTableData();//intialising the vectors with some data
        dtm=new DefaultTableModel(vdata,vcolname);
        data_tab=new JTable(dtm);//setting table model
        //data_tab.setPreferredScrollableViewportSize(new Dimension(500, 100)); 
        data_tab.setBounds(160,130,450,250);
        c.add(data_tab);
        WindowListener wndCloser = new WindowAdapter(){
            public void windowClosing(WindowEvent e) 
            {
               System.exit(0);
            }
        };
        addWindowListener(wndCloser);
        setSize(700,300);
        setVisible(true);
        show();
    }
    public static void main(String[] args) 
    {
        System.out.println("Hello World!");
        setDefaultLookAndFeelDecorated(true);
        new guidemo();
    }
    public void setTableData()
    {
    //intialise vectors with some data
        vdata=new Vector();
        vcolname=new Vector();
        vdata.removeAllElements();
        vdata.addElement(dat("Eliuh",90,900,"uy89"));
        vdata.addElement(dat("Eryuh",920,900,"uy89")); 
        vdata.addElement(dat("Elddh",940,900,"uy89"));
        vdata.addElement(dat("Elideu",90,900,"uy89"));
        vdata.addElement(dat("Elwciuh",760,900,"uy89"));
        vdata.addElement(dat("Elhhiuh",90,900,"uy89"));
        vdata.addElement(dat("Elicuh",100,900,"uy89"));
        vdata.addElement(dat("Eliuech",90,900,"uy89"));
        vcolname.addElement(cname("NAME","QStart","Qend","PID"));
    } 
    public Vector dat(String n,int v,int v1,String g)
    {
        Vector row = new Vector();
        row.addElement(n);
        row.addElement(new Integer(v));
        row.addElement(new Integer(v1));
        row.addElement(g);
        return row;
    }
    public Vector cname(String q, String w, String t, String y)
    {
        Vector row = new Vector();
        row.addElement(q);
        row.addElement(w);
        row.addElement(t);
        row.addElement(y);
        return row;
    }
}

[Joe Gilvary]

The exception occurs when doing the layout, and it's a ClassCastException. I think you need to write your own TableCellRenderer to display your dat and cname objects because they are not the kinds of objects that JTable knows how to display by default, e.g., String, Boolean, or Number.
HTH,
Joe

[Karan Raj]

hi,
Thanks for ur help.
vijay u r code is working fine..but i am not getting the column names for that table.
i am just learning jtables .I am not getting column names when i try to create a table with vectors.since a week i am trying this.
Can anyone explain what are specific things i need to take care while creating a table.

--karan

[Eddie Vanda]

Hi
I tried vijay's code but could only get the first column to show. Maybe I copied it wrong, or someone can spot my problem. I don't see any need for any special renderer. The last two methods merely generate the vectors and look ok to me. I used a little print loop to prove that vdata is ok.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
import java.util.*;
class guidemo extends JFrame
{
    private JTable data_tab;
    private JLabel ptitle;
    private Container c;
    private Vector vdata;
    private Vector vcolname;

    public guidemo()
    {
        super("EST Project Demo");
        DefaultTableModel dtm;
        c=getContentPane();
        c.setLayout(null);
        //c.setSize(500,500);//intialising the contentpane
        ptitle=new JLabel("EST project Details");
        ptitle.setBounds(60,30,150,40);
        c.add(ptitle);
        setTableData();//intialising the vectors with some data
        for (int r = 0; r < vdata.size (); r++) {
          System.out.println ();
          System.out.print ("r" + r + ": ");
          Vector vc = (Vector) vdata.elementAt (r);
            for (int c = 0; c < vc.size (); c++) {
              System.out.print (vc.elementAt (c) +  " ");
            }
        }
        dtm=new DefaultTableModel(vdata,vcolname);
        data_tab=new JTable(dtm);//setting table model
        System.out.println ("dtm getRowCount() = " + dtm.getRowCount());
        System.out.println ("dtm getColumnCount() = " + dtm.getColumnCount());
        //data_tab.setPreferredScrollableViewportSize(new Dimension(500, 100));
        data_tab.setBounds(160,130,450,250);
        c.add(data_tab);
        WindowListener wndCloser = new WindowAdapter(){
            public void windowClosing(WindowEvent e)
            {
               System.exit(0);
            }
        };
        addWindowListener(wndCloser);
        setSize(700,300);
        setVisible(true);
        show();
    }
    public static void main(String[] args)
    {
        System.out.println("Hello World!");
        setDefaultLookAndFeelDecorated(true);
        new guidemo();
    }
    public void setTableData()
    {
      //intialise vectors with some data
        vdata=new Vector();
        vcolname=new Vector();
        vdata.removeAllElements();
        vdata.addElement(dat("Eliuh",90,900,"uy89"));
        vdata.addElement(dat("Eryuh",920,900,"uy89"));
        vdata.addElement(dat("Elddh",940,900,"uy89"));
        vdata.addElement(dat("Elideu",90,900,"uy89"));
        vdata.addElement(dat("Elwciuh",760,900,"uy89"));
        vdata.addElement(dat("Elhhiuh",90,900,"uy89"));
        vdata.addElement(dat("Elicuh",100,900,"uy89"));
        vdata.addElement(dat("Eliuech",90,900,"uy89"));
        vcolname.addElement(cname("NAME","QStart","Qend","PID"));
    }
    public Vector dat(String n,int v,int v1,String g)
    {
        Vector row = new Vector();
        row.addElement(n);
        row.addElement(new Integer(v));
        row.addElement(new Integer(v1));
        row.addElement(g);
        return row;
    }
    public Vector cname(String q, String w, String t, String y)
    {
        Vector row = new Vector();
        row.addElement(q);
        row.addElement(w);
        row.addElement(t);
        row.addElement(y);
        return row;
    }
}

[Eddie Vanda]

Hi Karan,
I then reduced the size of your program by setting up arrays with a minimum support program. You need the scroll pane to show the headings but again I am not sure why it does not scroll when you reduce the JFrame size with the mouse.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
class GuiDemo1 extends JFrame {
    static private JTable data_tab;
    static private DefaultTableModel dtm;
    static private Container c;
    static Object [][] aData = {
      {new String ("Eliuh"),new Integer (90), new Integer (900), new String ("uy89")},
      {new String ("Eryuh"),new Integer (920), new Integer (900), new String ("uy89")},
      {new String ("Elddh"),new Integer (940), new Integer (900), new String ("uy89")},
      {new String ("Elideu"),new Integer (90), new Integer (900), new String ("uy89")},
      {new String ("Elwciuh"),new Integer (760), new Integer (900), new String ("uy89")},
      {new String ("Elhhiuh"),new Integer (90), new Integer (900), new String ("uy89")},
      {new String ("Elicuh"),new Integer (100), new Integer (900), new String ("uy89")},
      {new String ("Eliuech"),new Integer (90), new Integer (900), new String ("uy89")}
    };
    static String [] aColName = {"NAME","QStart","Qend","PID"};
    public GuiDemo1() {
        super("EST Project Demo 2");
        c=getContentPane();
        c.setLayout(new FlowLayout ());
        dtm=new DefaultTableModel (aData, aColName);
        System.out.println ("dtm getRowCount() = " + dtm.getRowCount());
        System.out.println ("dtm getColumnCount() = " + dtm.getColumnCount());
        data_tab=new JTable (dtm);//setting table model
        c.add(new JScrollPane (data_tab));
        pack ();
        setVisible(true);
        show();
    }
    public static void main(String[] args) {
        System.out.println("Hello World!!!");
        new GuiDemo1();
        for (int r = 0; r < aData.length; r++) {
          System.out.println ();
          System.out.print (r + ": ");
          for (int c = 0; c < aData [r].length; c++) {
            System.out.print (aData [r][c] + " ");
            //System.out.print (dtm.getValueAt (r, c) + " ");
          }
        }
    }
}

[ March 20, 2004: Message edited by: Eddie Vanda ]

[Eddie Vanda]

Hi Karan,
Sorry to take up more space, but I found the problem with the column count. You had added a vector level to the column names that was not necessary. I have also added a scroll pane so that your headings show up.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
import java.util.*;
class guidemo extends JFrame
{
    private JTable data_tab;
    private JLabel ptitle;
    private Container c;
    private Vector vdata;
    private Vector vcolname;

    public guidemo()
    {
        super("EST Project Demo");
        DefaultTableModel dtm;
        c=getContentPane();
        c.setLayout(null);
        //c.setSize(500,500);//intialising the contentpane
        ptitle=new JLabel("EST project Details");
        ptitle.setBounds(60,30,150,40);
        c.add(ptitle);
        setTableData();//intialising the vectors with some data
        System.out.println ("vcolname.size () = " + vcolname.size ());
        for (int c = 0; c < vcolname.size (); c++) {
          System.out.print (vcolname.elementAt (c) + " / ");
        }
        for (int r = 0; r < vdata.size (); r++) {
          System.out.println ();
          System.out.print ("r" + r + ": ");
          Vector vc = (Vector) vdata.elementAt (r);
            for (int c = 0; c < vc.size (); c++) {
              System.out.print (vc.elementAt (c) +  " ");
            }
        }
        dtm=new DefaultTableModel(vdata,vcolname);
        data_tab=new JTable(dtm);//setting table model
        System.out.println ("dtm getRowCount() = " + dtm.getRowCount());
        System.out.println ("dtm getColumnCount() = " + dtm.getColumnCount());
        //data_tab.setPreferredScrollableViewportSize(new Dimension(500, 100));
        JScrollPane jsp = new JScrollPane (data_tab);
        c.add(jsp);
        jsp.setBounds(160,130,450,250);
        WindowListener wndCloser = new WindowAdapter(){
            public void windowClosing(WindowEvent e)
            {
               System.exit(0);
            }
        };
        addWindowListener(wndCloser);
        setSize(700,300);
        setVisible(true);
        show();
    }
    public static void main(String[] args)
    {
        System.out.println("Hello World!");
        setDefaultLookAndFeelDecorated(true);
        new guidemo();
    }
    public void setTableData()
    {
      //intialise vectors with some data
        vdata=new Vector();
        vcolname=cname("NAME","QStart","Qend","PID");
        vdata.removeAllElements();
        vdata.addElement(dat("Eliuh",90,900,"uy89"));
        vdata.addElement(dat("Eryuh",920,900,"uy89"));
        vdata.addElement(dat("Elddh",940,900,"uy89"));
        vdata.addElement(dat("Elideu",90,900,"uy89"));
        vdata.addElement(dat("Elwciuh",760,900,"uy89"));
        vdata.addElement(dat("Elhhiuh",90,900,"uy89"));
        vdata.addElement(dat("Elicuh",100,900,"uy89"));
        vdata.addElement(dat("Eliuech",90,900,"uy89"));
    }
    public Vector dat(String n,int v,int v1,String g)
    {
        Vector row = new Vector();
        row.addElement(n);
        row.addElement(new Integer(v));
        row.addElement(new Integer(v1));
        row.addElement(g);
        return row;
    }
    public Vector cname(String q, String w, String t, String y)
    {
        Vector row = new Vector();
        row.addElement(q);
        row.addElement(w);
        row.addElement(t);
        row.addElement(y);
        System.out.println ("row.size () = " + row.size ());
        for (int c = 0; c < row.size (); c++) {
          System.out.print (row.elementAt (c) + " / ");
        }
        return row;
    }
}

[Karan Raj]

Hi Vanda,
Thanks for your help. your solution is very clear
Karan