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How to return positive and negative numbers when reading a file

I am writing a code that reads a file line by line and return only the following lines, as an example:

int int0 = (-953);
int int1 = (-411);
int int2 = 5471;
int int3 = 823;

After that I would like to return only the numbers both positive and negative. To do that, I wrote the following:

String str = line.replaceAll("\D+","");
System.out.println(str);


The result of running this code is:

0953
1411
25471
3823

The output that I seek is:

-953
-411
5471
823

How can I do that?

3 Answers
3

If you want to capture the last sequence of digits in a line (optionally preceded by a minus sign), you can do it with a capturing group, something like this:

Pattern p = Pattern.compile(".*?(-?\d+)\D*$");
String line = "int int0 = (-953);";
Matcher m = p.matcher(line);
if (m.matches()) {
System.out.println(m.group(1));
}


Result:

-953


How about this?

Due to your situation where each number will be after a = and what I want to do here is to remove everything else just as you once tried in this part (after =).

=

=

s = s.split("=")[1].replaceAll("[^-0-9]", "");


Local test your input with:

public static void main(String... args) {
String ss = {"int int0 = (-953);", "int int1 = (-411);", "int int2 = 5471;", "int int3 = 823;"};
for (String s : ss) {
s = s.split("=")[1].replaceAll("[^-0-9]", "");
System.out.println(s);
}
}


Output will be:

-953
-411
5471
823


Use this: ([-+]?)d+

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