RegexPerformanceTest

import java.util.regex.PatternSyntaxException;

public class RegexPerformanceTest
{
    public static void main(String[] args)
    {
        String regex1 = "(?im)^Hi there (.*$)(?<! is here)";
        String regex2 = "(?im)^Hi there (.*)(?<! is here)$";
        String errorTest = "Hi there John Doe is here";
        String successTest = "Hi there John Doe (jdo)";
        int repetitions = 1000000;
        try
        {
            System.out.println("Regex1, success: " + testRegexPerformance(regex1, successTest, repetitions));   // ~1200
            System.out.println("Regex1, error: " + testRegexPerformance(regex1, errorTest, repetitions));       // ~1200
            System.out.println("Regex2, success: " + testRegexPerformance(regex2, successTest, repetitions));   // ~1100
            System.out.println("Regex2, error: " + testRegexPerformance(regex2, errorTest, repetitions));       // ~1800
        }
        catch(PatternSyntaxException e)
        {
            e.printStackTrace();
        }
    }

    private static long testRegexPerformance(String regex, String subject, int numberOfRepetitions) throws PatternSyntaxException
    {
        boolean foundMatch;
        long endTime = 0;
        long startTime = 0;
        startTime = System.currentTimeMillis();
        for (int i = 0; i < numberOfRepetitions; i++)
        {
            foundMatch = subject.matches(regex);
        }
        endTime = System.currentTimeMillis();
        return endTime - startTime;
    }
}