Program: How to capture or extract a value(s) from text using regular expression in java?

The below example shows how to extract a specific pattern from a large text. The example tries to capture any IP addresses in the given text.

package com.java2novice.regex;

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

public class MyGroupRegex {

	private static Pattern ptn = 
			Pattern.compile("(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})");
	
	public static List<String> captureValues(String largeText){
		Matcher mtch = ptn.matcher(largeText);
		List<String> ips = new ArrayList<String>();
		while(mtch.find()){
			ips.add(mtch.group());
		}
		return ips;
	}
	
	public static void main(String a[]){
		String str = "Hi my machine IP is 10.20.30.40 and i would like "+
			"to access port 80 from the host 23.12.56.34, which internally"+
			"connects to 3.90.23.65. Please process the request";
		System.out.println(captureValues(str));
	}
}

[10.20.30.40, 23.12.56.34, 3.90.23.65]