1-) Java - frame kapatınca ana framenin kapanmaması

private void btnInfoActionPerformed(java.awt.event.ActionEvent evt) {                                        

        String sayi = txtHesap.getText().toString();

         if (sayi.equals("1453")) {

            info in = new info(sayi, "İSTANBULUN FETHİ");

            in.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

            in.setVisible(true);

        }

    }