CODEWITHSUNDEEP
javaswingvalidationgpscoordinates
zaxunobi
zaxunobi

Reputation: 940

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

Upvotes: 3

Views: 5165

Answers (2)

kadiro
kadiro

Reputation: 1116

I use regex to validate longitude and latitude:
longitude:

^[-+]?(180(\\.0+)?|((1[0-7]\\d)|([1-9]?\\d))(\\.\\d+)?)$

latitude:

^[-+]?([1-8]?\\d(\\.\\d+)?|90(\\.0+)?)$

    public boolean validateLong(String longitude) {
        booelan isValid = false;
        if (longitude != null) {
            String regexValidateLongitude = "^[-+]?(180(\\.0+)?|((1[0-7]\\d)|([1-9]?\\d))(\\.\\d+)?)$";
            isValid = longitude.trim().matches(regexValidateLongitude);
        }
        return isValid;
    }

    public boolean validateLat(String latitude) {
        booelan isValid = false;
        if (latitude != null) {
            String regexValidateLatitude = "^[-+]?([1-8]?\\d(\\.\\d+)?|90(\\.0+)?)$";
            isValid = latitude.matches(regexValidateLatitude);
        }
        return  isValid;

    }

Upvotes: 1

Dawood ibn Kareem
Dawood ibn Kareem

Reputation: 79808

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
}

Upvotes: 4

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