import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String regex = "(?:xxxxxxx)V[0-9]+_[0-9]+_[0-9]+(?:\\.[a-z]+)?";
		String string = "public void doSomething() {\n"
			 + "    return \"xxxxxxxV1_0_0.yyyyyyyy\";\n"
			 + "}";
		String subst = "xxxxxxxV2_0_0";
 
		Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
		Matcher matcher = pattern.matcher(string);
 
		String result = matcher.replaceAll(subst);
		System.out.println("Substitution result: " + result);
 
	}
}

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