public Object[] GetColumnData(int columnNo){
        
        if(!(columnNo<m_attributeCount)){
			JPanel frame = new JPanel();
			JOptionPane.showMessageDialog(frame,
                "Column Index out of bounds",
                "File error",
                JOptionPane.ERROR_MESSAGE);
        } else {
            m_columnData = new Object[m_entryCount];
            for(int i = 0; i<m_entryCount; i++){
                m_columnData[i] = m_data[i][columnNo];
            }
            return m_columnData;
        }
        return null;
    }