Clock.java

/* Estimate the elapsed time 
 * TODO:  Reduce if-else construct
 * 			overheads in elapsed time
 * 			calculations, add more precision
 */

public class Clock {
	private long start, elapsed, lap;
	public enum Resolution{
		MILLISEC, SEC, MINUTE, HOUR, DAY
	}
	
	public Clock(){
		start = -1;
		elapsed = 0;
	}
	
	public void startTimer(){
		start = System.currentTimeMillis();
		lap = start;
	}
	
	/* return elapsed milliseconds */
	public long getTotalElapsedTime(){
		/* start timer before using */
		if(start == -1){
			Logger.log(Logger.Status.ERR_CLOCK);
			return -1;
		}
		elapsed = System.currentTimeMillis() - start;
		return elapsed;
	}
	
	/* get elapsed time from start of clock (in different resolutions) */
	public long getTotalElapsedTime(Resolution reso){
		/* start timer before using */
		if(start == -1){
			Logger.log(Logger.Status.ERR_CLOCK);
			return -1;
		}
		
		elapsed = System.currentTimeMillis() - start;
		if(reso == Resolution.MILLISEC)
			return elapsed;
		
		long elapsedReso = elapsed/1000;
		if(reso == Resolution.SEC)
			return elapsedReso;
		
		elapsedReso /= 60;
		if(reso == Resolution.MINUTE)
			return elapsedReso;
		
		elapsedReso /= 60;
		if(reso == Resolution.HOUR)
			return elapsedReso;
		
		elapsedReso /= 24;
		return elapsedReso;
	}
	
	/* get elapsed time from last lap */
	public long getLapElapsedTime(){
		/* start timer before using */
		if(start == -1){
			Logger.log(Logger.Status.ERR_CLOCK);
			return -1;
		}
		
		long elapsedLap = System.currentTimeMillis() - lap;
		/* update current lap */
		lap = System.currentTimeMillis();
		return elapsedLap;
	}
	
	public long getLapElapsedTime(Resolution reso){
		/* start timer before using */
		if(start == -1){
			Logger.log(Logger.Status.ERR_CLOCK);
			return -1;
		}
		
		long elapsedLap = System.currentTimeMillis() - lap;
		if(reso == Resolution.SEC)
			elapsedLap /= 1000;
		else if(reso == Resolution.MINUTE)
			elapsedLap /= 60;
		else if(reso == Resolution.HOUR)
			elapsedLap /= 60;
		else if(reso == Resolution.DAY)
			elapsedLap /= 24;
		/* update current lap */
		lap = System.currentTimeMillis();
		return elapsedLap;
	}
	
	public void resetTimer(){
		start = System.currentTimeMillis();
		elapsed = 0;
	}
}