Question

I want to find all the negative floating point numbers in a string and store them in an array. I think my regex is correct, but something is wrong with my method.

Pattern pattern = Pattern.compile("[-]?[0-9]*[.][0-9]+$");      
String[] results = pattern.split("|AAA--A A05_#A| |-999.999| |-55.7|");

Answer 1

Your regex anchors the match to the end of the string, which isn’t what you want.

Likewise, Pattern.split doesn’t do what you want. Here’s some sample code to get you going:

Pattern pattern = Pattern.compile("[-]?[0-9]*[.][0-9]+");
String text = "|AAA--A A05_#A| |-999.999| |-55.7|";
Matcher matcher = pattern.matcher(text);
while (matcher.find()) {
    System.out.println(matcher.group());
}

This prints:

-999.999
-55.7

Obviously you could add to a list or something similar within the while loop. I don’t know of any method which returns a collection of all the matches, but you could easily write a utility method to do that yourself, based on code like the above.

EDIT: As noted in comments, if you only want to find negative values, the - shouldn’t be optional (and it doesn’t need to be in a set, either – just -? would have been fine).