Resultado do banco em Janela

public void calcula(Cheque x1) throws SQLException {

        double valorCheque = 0;
        String sql = "select sum(valor) as Total from cheque where datapag between datapag=? and datapag=?";
        PreparedStatement stmt = conexao.prepareStatement(sql);
        ResultSet rs = stmt.executeQuery();
        if (rs.next()){
        valorCheque = rs.getDouble("Total");
        }
        stmt.setString(1, x1.getValor());
        stmt.setString(2, x1.getDatapag());
        stmt.execute();
        stmt.close();

    }

public void calcular() {

        try {
            Cheque x1 = cheques.get(jTabelacheque.getSelectedRow());
            x1.setDatapag(jTdatacalculo1.getText());
            x1.setDatapag(jTdatacalculo2.getText());
            ChequeDao dao = new ChequeDao();
            dao.calcula(x1);
        } catch (SQLException ex) {
            Logger.getLogger(jTCheque.class.getName()).log(Level.SEVERE, null, ex);
        }

    }
private void jBCalcularActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
        
        int resp2 = JOptionPane.showConfirmDialog(this, "Deseja realmente alterar este cliente?",
              "Confirmação", JOptionPane.YES_NO_OPTION);
        if(resp2 == JOptionPane.YES_NO_OPTION){
         calcular();
         JOptionPane.showConfirmDialog(this,"total");
     }
    }