[levent]

Double has parseDouble method which tries to parse a String as a Double. You need to put it inside a try-catch block since it throws NumberFormatException.

You can write logic inside catch since it is called if the value is not a valid double!

Here is an example code:

Code:

double value;

try {
  // String textValue = the string from your JTextField
  value = Double.parseDouble(textValue);
  // if the code gets to here, it was recognizable as a double
}
catch(NumberFormatException e) {
  // if the code gets to here, it was NOT recognizable as a double
}