Java Split String using regular expression

Question

I have string that reads ParseGeoPoint[30.132531,31.312511]. How can I get the coordinates saved in double variables. i.e. I want to have double lat = 30.132531; and double lang = 31.312511;

Here is what I have tried:

String myText = "ParseGeoPoint[30.132531,31.312511]";
String [] latlong= myText.split("["); //it needs an escape character
String [] latlong2= latlong[1].split(",");
Double lat = Double.parseDouble(latlong2[0]);
String[] latlong3= latlong2[1].split("]");//also an escape character is needed here
Double lang = Double.parseDouble(latlong3[0]);

Two things: How to split on the square bracket given that it needs an escape character? Second, I feel it is too much to do it in this way. There must be simpler way. What is it?

janos · Accepted Answer · 2015-10-02 22:32:26Z

2

How to split on the square bracket given that it needs an escape character?

I guess you mean that this doesn't compile:

String [] latlong= myText.split("[");

To make it compile, escape the [:

String [] latlong= myText.split("\\[");

Here's another way to extract the doubles from the string using regular expressions:

Pattern pattern = Pattern.compile("ParseGeoPoint\\[([\\d.-]+),([\\d.-]+)]");
Matcher matcher = pattern.matcher(myText);
if (matcher.matches()) {
    lat = Double.parseDouble(matcher.group(1));
    lang = Double.parseDouble(matcher.group(2));
}

Another way is using substrings:

int bracketStartIndex = myText.indexOf('[');
int commaIndex = myText.indexOf(',');
int bracketEndIndex = myText.indexOf(']');
lat = Double.parseDouble(myText.substring(bracketStartIndex + 1, commaIndex));
lang = Double.parseDouble(myText.substring(commaIndex + 1, bracketEndIndex));

edited Oct 2, 2015 at 22:32

answered Oct 2, 2015 at 22:23

janos

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2 Comments

A_Matar Over a year ago

would you explain the regular expression you used in the first answer?

janos Over a year ago

The two ([\\d.-]+) are the most important. These are called capture groups, the inside of the (...) can be extracted using matcher.group(index) calls. There I match 1 or more digits or dot or minus sign. It's not very strict, for example ---... would match too, even though it's complete non-sense. But I hope you get the idea. The expression could be improved to make it more strict and robust. The rest of the expression outside the capture groups is fixed strings

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