Java tutorial
package edu.stanford.nlp.util; import edu.stanford.nlp.util.logging.Redwood; import java.io.PrintStream; import java.io.PrintWriter; import java.text.DecimalFormatSymbols; import java.text.NumberFormat; import java.text.DecimalFormat; import java.util.Locale; /** * A class for measuring how long things take. For backward * compatibility, this class contains static methods, but the * preferred usage is to instantiate a Timing object and use instance * methods. * * <p>To use, call {@link #startTime()} before running the code in * question. Call {@link #tick()} to print an intermediate update, and {@link #endTime()} to * finish the timing and print the result. You can optionally pass a descriptive * string and {@code PrintStream} to {@code tick} and {@code endTime} * for more control over what gets printed where.</p> * * <p>Example: time reading in a big file and transforming it:</p> * <p><code>Timing.startTime();<br> * String bigFileContents = IOUtils.slurpFile(bigFile);<br> * Timing.tick("read in big file", System.err);<br> * String output = costlyTransform(bigFileContents);<br> * Timing.endTime("transformed big file", System.err);</code></p> * * @author Bill MacCartney */ public class Timing { /** A logger for this class */ private static final Redwood.RedwoodChannels log = Redwood.channels(Timing.class); private static final long MILLISECONDS_TO_SECONDS = 1000L; private static final long SECOND_DIVISOR = 1000000000L; private static final long MILLISECOND_DIVISOR = 1000000L; /** * Stores the time at which the timer was started. Now stored as nanoseconds. */ private long start; /** * Stores the time at which the (static) timer was started. Stored as nanoseconds. */ private static long startTime = System.nanoTime(); /** Stores a suitable formatter for printing seconds nicely. */ private static final NumberFormat nf = new DecimalFormat("0.0", DecimalFormatSymbols.getInstance(Locale.ROOT)); /** * Constructs new Timing object and starts the timer. */ public Timing() { this.start(); } // start ========================================================== /** * Start timer. */ public void start() { start = System.nanoTime(); } // report ========================================================= /** * Return elapsed time (without stopping timer). * * @return Number of milliseconds elapsed */ public long report() { return (System.nanoTime() - start) / MILLISECOND_DIVISOR; } /** * Return elapsed time (without stopping timer). * * @return Number of nanoseconds elapsed */ public long reportNano() { return System.nanoTime() - start; } /** * Print elapsed time (without stopping timer). * * @param str Additional prefix string to be printed * @param stream PrintStream on which to write output * @return Number of milliseconds elapsed */ public long report(String str, PrintStream stream) { long elapsed = this.report(); stream.println(str + " Time elapsed: " + elapsed + " ms"); return elapsed; } /** * Print elapsed time to {@code System.err} (without stopping timer). * * @param str Additional prefix string to be printed * @return Number of milliseconds elapsed */ public long report(String str) { return this.report(str, System.err); } /** * Print elapsed time (without stopping timer). * * @param logger Logger to log a timed operation with * @param str Additional prefix string to be printed * @return Number of milliseconds elapsed */ public long report(Redwood.RedwoodChannels logger, String str) { long elapsed = this.report(); logger.info(str + " ... Time elapsed: " + toSecondsString(elapsed) + " sec"); return elapsed; } /** * Print elapsed time (without stopping timer). * * @param str Additional prefix string to be printed * @param writer PrintWriter on which to write output * @return Number of milliseconds elapsed */ public long report(String str, PrintWriter writer) { long elapsed = this.report(); writer.println(str + " ... Time elapsed: " + toSecondsString(elapsed) + " sec"); return elapsed; } /** Returns the number of seconds passed since the timer started in the form "d.d". */ public String toSecondsString() { return toSecondsString(report()); } /** Format with one decimal place elapsed milliseconds in seconds. * * @param elapsed Number of milliseconds elapsed * @return Formatted String */ public static String toSecondsString(long elapsed) { return nf.format(((double) elapsed) / MILLISECONDS_TO_SECONDS); } /** Format with one decimal place elapsed milliseconds. * * @param elapsed Number of milliseconds elapsed * @return Formatted String */ public static String toMilliSecondsString(long elapsed) { return nf.format(elapsed); } // restart ======================================================== /** * Restart timer. * * @return Number of milliseconds elapsed */ public long restart() { long elapsed = this.report(); this.start(); return elapsed; } /** * Print elapsed time and restart timer. * * @param str Additional prefix string to be printed * @param stream PrintStream on which to write output * @return Number of milliseconds elapsed */ public long restart(String str, PrintStream stream) { long elapsed = this.report(str, stream); this.start(); return elapsed; } /** * Print elapsed time to {@code System.err} and restart timer. * * @param str Additional prefix string to be printed * @return Number of milliseconds elapsed */ public long restart(String str) { return this.restart(str, System.err); } /** * Print elapsed time and restart timer. * * @param str Additional prefix string to be printed * @param writer PrintWriter on which to write output * @return Number of milliseconds elapsed */ public long restart(String str, PrintWriter writer) { long elapsed = this.report(str, writer); this.start(); return elapsed; } /** * Print the timing done message with elapsed time in x.y seconds. * Restart the timer too. */ public void end(String msg) { long elapsed = System.nanoTime() - start; log.info(msg + " done [" + nf.format(((double) elapsed) / SECOND_DIVISOR) + " sec]."); this.start(); } // stop =========================================================== /** * Stop timer. * * @return Number of milliseconds elapsed */ public long stop() { long elapsed = this.report(); this.start = 0; return elapsed; } /** * Print elapsed time and stop timer. * * @param str Additional prefix string to be printed * @param stream PrintStream on which to write output * @return Number of milliseconds elapsed */ public long stop(String str, PrintStream stream) { this.report(str, stream); return this.stop(); } /** * Print elapsed time to {@code System.err} and stop timer. * * @param str Additional prefix string to be printed * @return Number of milliseconds elapsed */ public long stop(String str) { return stop(str, System.err); } /** * Print elapsed time and stop timer. * * @param str Additional prefix string to be printed * @param writer PrintWriter on which to write output * @return Number of milliseconds elapsed */ public long stop(String str, PrintWriter writer) { this.report(str, writer); return this.stop(); } // startTime ====================================================== /** * Start (static) timer. */ public static void startTime() { startTime = System.nanoTime(); } // endTime ======================================================== /** * Return elapsed time on (static) timer (without stopping timer). * * @return Number of milliseconds elapsed */ public static long endTime() { return (System.nanoTime() - startTime) / MILLISECOND_DIVISOR; } /** * Print elapsed time on (static) timer (without stopping timer). * * @param str Additional prefix string to be printed * @param stream PrintStream on which to write output * @return Number of milliseconds elapsed */ public static long endTime(String str, PrintStream stream) { long elapsed = endTime(); stream.println(str + " Time elapsed: " + (elapsed) + " ms"); return elapsed; } /** * Print elapsed time on (static) timer to * {@code System.err} (without stopping timer). * * @param str Additional prefix string to be printed * @return Number of milliseconds elapsed */ public static long endTime(String str) { return endTime(str, System.err); } // chris' new preferred methods 2006 for loading things etc. /** Print the start of timing message to stderr and start the timer. */ public void doing(String str) { log.info(str + " ... "); start(); } /** Finish the line from doing() with the end of the timing done message * and elapsed time in x.y seconds. */ public void done() { log.info("done [" + toSecondsString() + " sec]."); } /** Give a line saying that something is " done". */ public void done(String msg) { log.info(msg + " done [" + toSecondsString() + " sec]."); } public void done(StringBuilder msg) { msg.append(" done [").append(toSecondsString()).append(" sec]."); log.info(msg.toString()); } /** This method allows you to show the results of timing according to another class' logger. * E.g., {@code timing.done(logger, "Loading lexicon")}. * * @param logger Logger to log a timed operation with * @param msg Message to report. */ public void done(Redwood.RedwoodChannels logger, StringBuilder msg) { msg.append("... done [").append(toSecondsString()).append(" sec]."); logger.info(msg.toString()); } public void done(Redwood.RedwoodChannels logger, String msg) { logger.info(msg + " ... done [" + toSecondsString() + " sec]."); } /** Print the start of timing message to stderr and start the timer. */ public static void startDoing(String str) { log.info(str + " ... "); startTime(); } /** Finish the line from startDoing with the end of the timing done message * and elapsed time in x.y seconds. */ public static void endDoing() { long elapsed = System.nanoTime() - startTime; log.info("done [" + nf.format(((double) elapsed) / SECOND_DIVISOR) + " sec]."); } /** Finish the line from startDoing with the end of the timing done message * and elapsed time in x.y seconds. */ public static void endDoing(String msg) { long elapsed = System.nanoTime() - startTime; log.info(msg + " done [" + nf.format(((double) elapsed) / SECOND_DIVISOR) + " sec]."); } // tick =========================================================== /** * Restart (static) timer. * * @return Number of milliseconds elapsed */ public static long tick() { long elapsed = (System.nanoTime() - startTime) / MILLISECOND_DIVISOR; startTime(); return elapsed; } /** * Print elapsed time and restart (static) timer. * * @param str Additional prefix string to be printed * @param stream PrintStream on which to write output * @return Number of milliseconds elapsed */ public static long tick(String str, PrintStream stream) { long elapsed = tick(); stream.println(str + " Time elapsed: " + (elapsed) + " ms"); return elapsed; } /** * Print elapsed time to {@code System.err} and restart (static) timer. * * @param str Additional prefix string to be printed * @return Number of milliseconds elapsed */ public static long tick(String str) { return tick(str, System.err); } // import java.util.Calendar; // import java.util.TimeZone; // // Calendar cal = Calendar.getInstance(TimeZone.getTimeZone("EST")); // Calendar cal = Calendar.getInstance(TimeZone.getDefault()); // String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss"; // java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat(DATE_FORMAT); // // sdf.setTimeZone(TimeZone.getTimeZone("EST")); // sdf.setTimeZone(TimeZone.getDefault()); // System.out.println("Now : " + sdf.format(cal.getTime())); @Override public String toString() { return "Timing[start=" + startTime + ']'; } }