public   class  DataModel  extends  AbstractTableModel {

   String[] s =  new  String[] {"a", "b", "c", "d"};

     private  Object[][] data = {
            {"1", "2", "3","4"},
            {"5", "6", "7","8"},
            {"9", "10", "11","12"},
            {"13", "14", "15","16"},
            {"17", "18", "19","20"},
            {"21", "22", "23","24"}
    };

     public   int  getColumnCount() {
         return  data[ 0 ].length;
    }

     public   int  getRowCount() {
         return  data.length;
    }

     public  Object getValueAt( int  rowIndex,  int  columnIndex) {
         return  data[rowIndex][columnIndex];
    }
    public  String getColumnName( int  column) {
        return  s[column].toString();
   }

    public   boolean  isCellEditable( int  row,  int  column) {
        return  true;
   }
    public   void  setValueAt(Object value,  int  row,  int  col) {
       data[row][col] = value;
       fireTableCellUpdated(row, col);
  }
}
//....................

        JTable table =  new  JTable( new  DataModel());
         this .getContentPane().add(table);