Extract Integer Part in String

Question

What is the best way to extract the integer part of a string like

Hello123

How do you get the 123 part. You can sort of hack it using Java\

Answer 1

I had been thinking Michael's regex was the simplest solution possible, but on second thought just "\d+" works if you use Matcher.find() instead of Matcher.matches():

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

public class Example {

    public static void main(String[] args) {
        String input = "Hello123";
        int output = extractInt(input);

        System.out.println("input [" + input + "], output [" + output + "]");
    }

    //
    // Parses first group of consecutive digits found into an int.
    //
    public static int extractInt(String str) {
        Matcher matcher = Pattern.compile("\\d+").matcher(str);

        if (!matcher.find())
            throw new NumberFormatException("For input string [" + str + "]");

        return Integer.parseInt(matcher.group());
    }
}