import java.util.ArrayList;
import java.util.List;

public class SplitStringEvery {
	private static final int numberOfRepeats = 3000000;
	private static final String textToRepeat = "1";
	private static final int interval = 1;
	private static final int numberOfTestsToRun = 10;

	public static void main(String[] args) {		
		StringBuilder sb = new StringBuilder(numberOfRepeats * textToRepeat.length());
		
		for (int i = 0; i < numberOfRepeats; i++) {
			sb.append(textToRepeat);
		}
		final String stringToSplit = sb.toString();
		
		List<Long> elapsedTimesSplit =  new ArrayList<Long>(numberOfTestsToRun);
		List<Long> elapsedTimesSubstring =  new ArrayList<Long>(numberOfTestsToRun);
		
		long startTime;
		long endTime;
		
		
		//Tests to run
		for (int i = 0; i < numberOfTestsToRun; i++) {
			startTime = System.currentTimeMillis();
			stringToSplit.split("(?<=\\G.{" + interval + "})");
			endTime = System.currentTimeMillis();
			elapsedTimesSplit.add(endTime - startTime);
			
		    //-------------

			startTime = System.currentTimeMillis();
			splitStringEvery(stringToSplit, interval);
			endTime = System.currentTimeMillis();
			elapsedTimesSubstring.add(endTime - startTime);
		}
		
		//Calculate averages:
	    
	    long splitSum = 0;
	    long substringSum = 0;
	    for (int i = 0; i < numberOfTestsToRun; i++) {
	    	splitSum += elapsedTimesSplit.get(i);
	    	substringSum += elapsedTimesSubstring.get(i);
		}
	    
	    long splitAvg = splitSum / elapsedTimesSplit.size();
	    long substringAvg = substringSum / elapsedTimesSplit.size();
	    
	    //Print data:
	    System.out.println("Split:");
	    System.out.println(elapsedTimesSplit);
	    
	    System.out.println("Substring:");
	    System.out.println(elapsedTimesSubstring);
	    
	    System.out.println("\nAverage:");
	    System.out.println("Split: " + splitAvg + " Substring: " + substringAvg);
	    
	    System.out.println("\nFactor:");
	    System.out.println(splitAvg / (double)substringAvg);
	}
	
	public static String[] splitStringEvery(String s, int interval) {
		int arrayLength = (int) Math.ceil(((s.length() / (double)interval)));
		String[] result = new String[arrayLength];
		
		int j = 0;
		int lastIndex = result.length - 1;
		for (int i = 0; i < lastIndex; i++) {
			result[i] = s.substring(j, j + interval);
			j += interval;
		}
		result[lastIndex] = s.substring(j);
		
		return result;
	}
}