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;
	}
}