Java Regex 获取所有数字

Question

I need to retrieve all numbers from a String, example :

"a: 1 | b=2 ; c=3.2 / d=4,2"

I want get this result :

• 1
• 2
• 3.2
• 4,2

So, i don't know how to say that in Regex on Java.

Actually, i have this :

(?<=\D)(?=\d)|(?<=\d)(?=\D)

He split letter and number (but the double value is not respected), and the result is :

• 1
• 2
• 3
• 2 (problem)
• 4
• 2 (problem)

Can you help me ?

Thanks :D

Answer 1

You might use a capturing group with a character class :

[a-z][:=]\h*(\d+(?:[.,]\d+)?)

Explanation

• [az] Word boundary, match a char az
• [:=] Match either : or =
• \\h* Match 0+ horizontal whitespace chars
• ( Capture group 1
  • \\d+(?:[.,]\\d+)? Match 1+ digits with an optional decimal part with either . or ,
• ) Close group

Regex demo | Java demo

For example

String regex = "[a-z][:=]\\h*(\\d+(?:[.,]\\d+)?)";
String string = "a: 1 | b=2 ; c=3.2 / d=4,2";

Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(string);

while (matcher.find()) {
    System.out.println(matcher.group(1));
}

Output

1
2
3.2
4,2

Answer 2

You can use

/\d+(?:[.,]\d+)?/g

demo

Answer 3

You can do it as follows:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) throws InterruptedException {
        // Test
        String s = "a: 1 | b=2 ; c=3.2 / d=4,2";
        showNumbers(s);
    }

    static void showNumbers(String s) {
        Pattern regex = Pattern.compile("\\d[\\d,.]*");
        Matcher matcher = regex.matcher(s);
        while (matcher.find()) {
            System.out.println(matcher.group());
        }
    }
}

Output:

1
2
3.2
4,2

Answer 4

You may jsut need a regex like (\\d(?:[.,]\\d)?) that

• find a digit
• evently dot/comma + other digit after

The multi-digit version is (\\d+(?:[.,]\\d+)?)

String value = "a: 1 | b=2 ; c=3.2 / d=4,2";
Pattern p = Pattern.compile("(\\d(?:[.,]\\d)?)");
Matcher m = p.matcher(value);
while (m.find()) {
    System.out.println(m.group());
}
//        1
//        2
//        3.2
//        4,2