import java.math.BigDecimal; import java.math.MathContext; import java.math.RoundingMode; import java.text.DecimalFormat; import java.time.LocalTime; import java.time.format.DateTimeFormatter; import java.time.temporal.ChronoUnit; import java.util.Objects; import java.util.concurrent.TimeUnit; import java.util.regex.Pattern; public class SimpleLoadingBar { private static final String TIME_FORMAT = "HH:mm"; private static final DateTimeFormatter TIME_FORMATTER = DateTimeFormatter.ofPattern(TIME_FORMAT); private static final Pattern TIME_PATTERN = Pattern.compile("(?>[01]\\d|2[0-4]):[0-5]\\d"); private static final DecimalFormat PERCENTAGE_FORMAT = new DecimalFormat("00.00"); private static final int MINS_PER_HOUR = 60; private static final BigDecimal MINS_PER_HOUR_BD = BigDecimal.valueOf(MINS_PER_HOUR); private static final int LINE_LENGTH = 100; private static final MathContext MC_INTEGER = new MathContext(1, RoundingMode.HALF_EVEN); private static final BigDecimal ONE_HUNDRED_PERCENT = BigDecimal.valueOf(100); private final String title; private final LocalTime startTime; private LocalTime endTime; private long totalMinutes; private BigDecimal totalMinutesBD; private SimpleLoadingBar(LocalTime startTime, LocalTime endTime, String title) { this.startTime = startTime; setEndTime(endTime); this.title = initTitle(title); } public static void main(String[] args) { if (args.length > 0 && Objects.equals(args[0], "--help")) { printHelp(); return; } verifyMinimumNumberOfArgs(args); String nextArg = args[0]; verifyTimeFormat(nextArg, "Erstes Argument"); var firstTime = LocalTime.parse(nextArg, TIME_FORMATTER); LocalTime startTime = null; String title = ""; LocalTime endTime = null; if (args.length > 1) { nextArg = args[1]; if ("-msg".equals(nextArg)) { title = args.length > 2 ? args[2] : title; } else { verifyTimeFormat(nextArg, "Zweites Argument"); endTime = LocalTime.parse(nextArg, TIME_FORMATTER); } } if (endTime == null) { startTime = LocalTime.now(); endTime = firstTime; } else { startTime = firstTime; } if (args.length == 2 || !title.isBlank()) { new SimpleLoadingBar(startTime, endTime, title).showLoadingBar(); return; } // if there are 3 arguments, the third will be discarded. boolean hasTitleArg = args.length > 3 && "-msg".equals(args[2]); title = hasTitleArg ? args[3] : title; new SimpleLoadingBar(startTime, endTime, title).showLoadingBar(); } private static void println(Object o) { System.out.println(o); } private static void print(Object o) { System.out.print(o); } private static void printHelp() { println("Mögliche Argumente für LoadingBar:\n" + "Startzeit, Endzeit, Endnachricht (Optional)\n" + TIME_FORMAT + " " + TIME_FORMAT + " -msg \n" + "Endzeit (Startzeit = jetzt), Endnachricht (Optional)\n" + TIME_FORMAT + " -msg \n" ); } private static void verifyMinimumNumberOfArgs(String[] args) { if (args.length >= 1) { return; } println("Mindestens 1 Argument muss gegeben sein."); printHelp(); System.exit(1); } private static void verifyTimeFormat(String param, String errMsgPrefix) { if (TIME_PATTERN.matcher(param).matches()) { return; } println(errMsgPrefix + " \"" + param + "\" muss Uhrzeitformat (" + TIME_FORMAT + ") entsprechen."); System.exit(1); } private void setEndTime(LocalTime endTime) { this.endTime = endTime; this.totalMinutes = startTime.until(endTime, ChronoUnit.MINUTES); this.totalMinutesBD = BigDecimal.valueOf(totalMinutes); } private String initTitle(String inputTitle) { String fallbackTitle = "Ende! Endzeit " + TIME_FORMATTER.format(endTime) + " erreicht."; String effectiveTitle = inputTitle == null || inputTitle.isBlank() ? fallbackTitle : inputTitle; String separator = "*".repeat(effectiveTitle.length()); return separator + "\n" + effectiveTitle + "\n" + separator; } private void showLoadingBar() { long passedMinutes = startTime.until(LocalTime.now().truncatedTo(ChronoUnit.MINUTES), ChronoUnit.MINUTES); // long passedMinutes = 0; // DEBUG if (passedMinutes > totalMinutes) { passedMinutes = totalMinutes; } else if (passedMinutes < 0) { var now = LocalTime.now().truncatedTo(ChronoUnit.SECONDS); println("!ACHTUNG! Startzeit \"" + startTime + ":00\" liegt in der Zukunft von jetzt an (" + now + ") gesehen."); } println(minutesToTimeString(totalMinutesBD) + " gesamt; Endzeit: " + TIME_FORMATTER.format(endTime)); while (passedMinutes < totalMinutes) { print(fillLoadingBar(passedMinutes, true)); waitUntilNextMinute(); passedMinutes++; } println(fillLoadingBar(passedMinutes, false)); println(title); } private String fillLoadingBar(long passedMinutes, boolean progressive) { var nonNegativePassedMinutes = BigDecimal.valueOf(passedMinutes < 0 ? 0 : passedMinutes); BigDecimal wholePercentage = ONE_HUNDRED_PERCENT // kind of reverse dreisatz to avoid having e.g. 99.9999 instead of 100 % .multiply(nonNegativePassedMinutes) .divide(totalMinutesBD, MathContext.DECIMAL64); int numberOfEquals = wholePercentage.intValue(); var sb = new StringBuilder("["); for (int i = 0; i < LINE_LENGTH; i++) { if (i < numberOfEquals) { sb.append("="); } else { sb.append("-"); } } BigDecimal remainingMinutes = totalMinutesBD.subtract(nonNegativePassedMinutes); sb.append("] ").append(PERCENTAGE_FORMAT.format(wholePercentage)).append("% ") .append(minutesToTimeString(nonNegativePassedMinutes)).append(" - ").append(minutesToTimeString(remainingMinutes)); if (progressive) { sb.append("\r"); } return sb.toString(); } private String minutesToTimeString(BigDecimal minutes) { BigDecimal[] hoursAndMinutes = minutes.divideAndRemainder(MINS_PER_HOUR_BD, MC_INTEGER); return LocalTime.of(hoursAndMinutes[0].intValue(), hoursAndMinutes[1].intValue()).format(TIME_FORMATTER); } private void waitUntilNextMinute() { try { var now = LocalTime.now(); var oneMinuteLater = now.plusMinutes(1).truncatedTo(ChronoUnit.MINUTES); /* We wait whole seconds to not make it overly complicated. That results in cut milliseconds: if we would have to wait 1 second and 526 milliseconds, we wait only 1 second. So, adjust for ignored milliseconds, add +1 second as it is better to switch between 00 and 01 as between 59 and 00 */ TimeUnit.SECONDS.sleep(now.until(oneMinuteLater, ChronoUnit.SECONDS) + 1); // TimeUnit.MILLISECONDS.sleep(100L); // DEBUG } catch (InterruptedException ie) { Thread.currentThread().interrupt(); throw new RuntimeException(ie); } } }