How to validate geographic coordinates?

I'm trying to validate the text of a JTextField. The content of this textfield should be something like this 66.160507, -153.369141 or 66.160507,-153.369141 (without whitespace after the comma). So far I validate only the range for both latitude and longitude. Here:

 String [] splitted = jtextField.getText().split(",");
 double latitude = Double.parseDouble(splitted[0]);
 double longitude = Double.parseDouble(splitted[1])

if(latitude < -90 || latitude > 90)
  return false;
else
  continue;

if(longitude < -180 || longitude > 180)
      return false;
    else
      continue;

but now how can I check whether the text in the JTextField is in the right format and order? I need to validate these two cases:

must be a double -> must be a comma -> must be a whitespace -> must be a double 
must be a double -> must be a comma -> must be a double 

One option would be to use a regular expression to validate the form of what's in your text field. You can read up on the different symbols you can use in a regular expression at the Javadoc for the Pattern class, but some of the ones you might use would be

• * any number of matches of what goes before (including none);
• + one or more matches of what goes before;
• ? zero or one matches of what goes before;
• [ ] a range of characters.
• \. a dot (the backslash will need escaping if it's in a Java String literal),
• \s any whitespace (and this backslash will also need escaping in a String literal).

Putting this all together you might come up with a regular expression like this.

-?[1-9][0-9]*(\.[0-9]+)?,\s*-?[1-9][0-9]*(\.[0-9]+)?

to match a pair of latitude and longitude.

This matches

• optionally a minus sign,
• a number other than 0, for the first digit,
• any number of other digits (even none),
• optionally, a sequence consisting of a decimal point, then any number of other digits,
• a comma,
• any number of whitespace characters (even none),
• the first four bullet points in this paragraph, all over again.

You could then write code like this.

String textValue = jtextField.getText();
String twoDoublesRegularExpression = "-?[1-9][0-9]*(\\.[0-9]+)?,\\s*-?[1-9][0-9]*(\\.[0-9]+)?";

if (textValue.matches(twoDoublesRegularExpression)) {
    // this value is OK
}