How to extract numbers from a string and get an array of ints?
Pattern p = Pattern.compile("-?\\d+");
Matcher m = p.matcher("There are more than -2 and less than 12 numbers here");
while (m.find()) {
System.out.println(m.group());
}
... prints -2
and 12
.
-? matches a leading negative sign -- optionally. \d matches a digit, and we need to write \
as \\
in a Java String though. So, \d+ matches 1 or more digits.
Pattern p = Pattern.compile("[0-9]+");
Matcher m = p.matcher(myString);
while (m.find()) {
int n = Integer.parseInt(m.group());
// append n to list
}
// convert list to array, etc
You can actually replace [0-9] with \d, but that involves double backslash escaping, which makes it harder to read.
StringBuffer sBuffer = new StringBuffer();
Pattern p = Pattern.compile("[0-9]+.[0-9]*|[0-9]*.[0-9]+|[0-9]+");
Matcher m = p.matcher(str);
while (m.find()) {
sBuffer.append(m.group());
}
return sBuffer.toString();
This is for extracting numbers retaining the decimal
What about to use replaceAll
java.lang.String method:
String str = "qwerty-1qwerty-2 455 f0gfg 4";
str = str.replaceAll("[^-?0-9]+", " ");
System.out.println(Arrays.asList(str.trim().split(" ")));
Output:
[-1, -2, 455, 0, 4]
Description
[^-?0-9]+
[
and]
delimites a set of characters to be single matched, i.e., only one time in any order^
Special identifier used in the beginning of the set, used to indicate to match all characters not present in the delimited set, instead of all characters present in the set.+
Between one and unlimited times, as many times as possible, giving back as needed-?
One of the characters “-” and “?”0-9
A character in the range between “0” and “9”