Java SE (Java Platform, Standard Edition)

Sir,

I am using the following code and get subjected error.


{error}{
java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1011)
at java.lang.Double.parseDouble(Double.java:540)
at invoice.InvoiceController$4.changed(InvoiceController.java:192)
}{error}

and

{

//wt ,  sValExlSt1 and sPrice1 are numbers


 wt1.textProperty().addListener(new ChangeListener<String>() {
                public void changed(ObservableValue<? extends String> observable, String oldValue, String newValue) {
                    sValExlSt1.setText(String.valueOf(
                            Double.parseDouble(newValue)  * Double.parseDouble(sPrice1.getText())));
                }
            });
        } catch (NumberFormatException e1) {
        }

}

Please help.