first version of class that tracks target liquid intake over time

DrinkingBar.java

@@ -0,0 +1,70 @@
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.io.IOException;
+import java.math.BigDecimal;
+import java.math.MathContext;
+import java.math.RoundingMode;
+import java.nio.charset.StandardCharsets;
+import java.text.DecimalFormat;
+import java.time.LocalTime;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.ChronoUnit;
+import java.util.concurrent.TimeUnit;
+
+public class DrinkingBar {
+
+   private static final DateTimeFormatter TIME_FORMATTER = DateTimeFormatter.ofPattern("HH:mm");
+   private static final int MINS_PER_HOUR = 60;
+   private static final int MINS_PER_HALF_HOUR = MINS_PER_HOUR / 2;
+   private static final int MINUTES_BEFORE_PAUSE = 4 * MINS_PER_HOUR + MINS_PER_HALF_HOUR;
+   private static final int MINUTES_WITH_PAUSE = 6 * MINS_PER_HOUR;
+   private static final DecimalFormat LITER_FORMAT = new DecimalFormat("0.00");
+   private static final BigDecimal MINS_PER_HOUR_BD = BigDecimal.valueOf(MINS_PER_HOUR);
+   private static final MathContext MC_INTEGER = new MathContext(1, RoundingMode.HALF_EVEN);
+
+
+   public static void main(String[] args) throws IOException {
+      var br = new BufferedReader(new InputStreamReader(System.in, StandardCharsets.UTF_8));
+      System.out.print("Ankunftszeit: ");
+      var startTime = LocalTime.parse(br.readLine(), TIME_FORMATTER).truncatedTo(ChronoUnit.MINUTES);
+
+
+      long totalMinutes = 8 * MINS_PER_HOUR + MINS_PER_HALF_HOUR;
+      long passedMinutes = startTime.until(LocalTime.now().truncatedTo(ChronoUnit.MINUTES), ChronoUnit.MINUTES);
+      // long passedMinutes = 0; // DEBUG
+      boolean firstPrint = true;
+      double prevPrintedLitres = 0.0;
+      while (passedMinutes < totalMinutes) {
+         if (passedMinutes <= MINUTES_BEFORE_PAUSE || passedMinutes > MINUTES_WITH_PAUSE) {
+            double currentLitres = 2.0 / totalMinutes * passedMinutes;
+            double printedLitres = currentLitres - (currentLitres % 0.25) + 0.25;
+            String cursorReset = firstPrint ? "" : "\r";
+            if (firstPrint || printedLitres - prevPrintedLitres == 0.25) {
+               System.out.print(cursorReset + "Aktuelles Volumen: " + LITER_FORMAT.format(printedLitres) + "L");
+            }
+            prevPrintedLitres = printedLitres;
+            if (firstPrint) {
+               firstPrint = false;
+            }
+         }
+         try {
+            var now = LocalTime.now();
+            var oneMinuteLater = now.plusMinutes(1).truncatedTo(ChronoUnit.MINUTES);
+            // +1 second to adjust for ignored milliseconds 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) {
+            throw new RuntimeException(ie);
+         }
+         passedMinutes++;
+      }
+      System.out.println("");
+   }
+
+
+   private static String minutesToTimeString(long minutes) { // DEBUG
+      var minutesBD = BigDecimal.valueOf(minutes);
+      BigDecimal[] hoursAndMinutes = minutesBD.divideAndRemainder(MINS_PER_HOUR_BD, MC_INTEGER);
+      return LocalTime.of(hoursAndMinutes[0].intValue(), hoursAndMinutes[1].intValue()).format(TIME_FORMATTER);
+   }
+}