Simple class to calculate time intervals

gistfile1.txt

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Calendar;

/**
 * An utility class to measure time processing.
 *
 * @author Andre Luis de Oliveira Dias
 * @date 29/04/2014.
 */
public final class Timer {

    private long initial = 0L;
    private String prefix;
    private static final Logger LOGGER = LoggerFactory.getLogger(Timer.class);

    public Timer() {
        super();
        this.initial = System.currentTimeMillis();
    }

    public Timer(String prefix) {
        this();
        this.prefix = prefix;
    }

    public String stop() {
        final StringBuilder sb = new StringBuilder();

        if (this.prefix != null) {
            sb.append("[").append(this.prefix).append("]");
        }

        sb.append("Time Elapsed: ").append(this.timeElapsed());

        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug(sb.toString());
        }

        return sb.toString();
    }

    public String timeElapsed() {
        final StringBuilder sb = new StringBuilder();
        final long time = (Calendar.getInstance().getTimeInMillis() - this.initial);

        sb.append((time / 1000.0)).append(" second(s).");

        return sb.toString();
    }

    public static void main (String[] args) throws Exception {
        Timer c = new Timer();
        Timer c1 = new Timer("C1");
        Thread.sleep(3000);

        c.stop();
        c1.stop();
    }
}