Getting classCastException while using DefaultTableModel

[Sowmiya Selvamani]

I m using NetBeans5.5

   public Vector getColumnNames()
   {
       Vector vtor=new Vector();
       try
       {
       vtor.add("COLUMN_NAME");
       vtor.add("DATE_TYPE");
       vtor.add("NULLABLE");
       vtor.add("COLUMN_ID");
       }
       catch(Exception e)
       {
           System.out.println("ERROR!!!"+e.getMessage());
       }
       return vtor;
   }
   public Vector getColumnValues()
   {
       Connection cc=start();
       String sql="select column_name,data_type,nullable,column_id   from     user_tab_cols where table_name like 'INVTORY'  order by column_id";
       String resultQuery=null;
       Vector v1=new Vector();
       try
       {
           stmt = cc.createStatement();
          rs   = stmt.executeQuery(sql);
        while(rs.next())
          {   
             v1.add(rs.getString("column_name"));
             v1.add(rs.getString("data_type"));
             v1.add(rs.getString("nullable"));
             v1.add(rs.getString("column_id"));
          }
        }
        catch(Exception e)
        {
            System.out.println(e.getMessage());
        }
        return v1;
       }       
  

When I run the below code I got the exception as

 Vector vctor=new Main().getColumnValues();
       Vector vctor1=new Main().getColumnNames(); 
        jTable1.setModel(new javax.swing.table.DefaultTableModel(vctor,vctor1)); 
   

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String
at javax.swing.table.DefaultTableModel.justifyRows(DefaultTableModel.java:242)
at javax.swing.table.DefaultTableModel.setDataVector(DefaultTableModel.java:198)
at javax.swing.table.DefaultTableModel.<init>(DefaultTableModel.java:133)

[Rob Spoor]

DefaultTableModel's first Vector should contain Vectors that contain Strings, not contain the Strings themselves.

If you change

v1.add(rs.getString("column_name"));
v1.add(rs.getString("data_type"));
v1.add(rs.getString("nullable"));
v1.add(rs.getString("column_id"));

into

Vector v = new Vector();
v.add(rs.getString("column_name"));
v.add(rs.getString("data_type"));
v.add(rs.getString("nullable"));
v.add(rs.getString("column_id"));
v1.add(v);

it should work.