New Examples

Author: lokeshgupta1981

src/main/java/com/howtodoinjava/core/basic/math/MathFloorDivCeilDiv.java

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+package com.howtodoinjava.core.basic.math;
+
+public class MathFloorDivCeilDiv {
+
+  public static void main(String[] args) {
+
+  }
+
+}

src/main/java/com/howtodoinjava/core/datetime/ConvertBetweenMonthNameAndNumber.java

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+package com.howtodoinjava.core.datetime;
+
+import java.time.Month;
+import java.time.format.TextStyle;
+import java.util.Arrays;
+import java.util.Locale;
+import java.util.Optional;
+
+public class ConvertBetweenMonthNameAndNumber {
+
+  public static void main(String[] args) {
+
+    // MONTH NUMBER -> NAME
+
+    System.out.println(monthNumberToAbbr(1));
+    System.out.println(monthNumberToFullName(1));
+    System.out.println(monthNumberToName(1));
+
+    // MONTH ABBR -> Number
+
+    System.out.println(monthNameToNumber("January"));
+    System.out.println(monthAbbrToNumber("Jan"));
+
+    // MONTH NAME -> NAME
+
+    System.out.println(monthAbbrToFullName("Jan"));
+  }
+
+  public static String monthNumberToAbbr(int monthNumber) {
+    return Month.of(monthNumber).getDisplayName(
+        TextStyle.SHORT, Locale.getDefault()
+    );
+  }
+
+  public static String monthNumberToFullName(int monthNumber) {
+    return Month.of(monthNumber).getDisplayName(
+        TextStyle.FULL, Locale.getDefault()
+    );
+  }
+
+  public static String monthNumberToName(int monthNumber) {
+    return Month.of(monthNumber).name();
+  }
+
+  public static int monthNameToNumber(String monthName) {
+    return Month.valueOf(monthName.toUpperCase()).getValue();
+  }
+
+  public static int monthAbbrToNumber(String abbreviation) {
+    Optional<Month> monthOptional = Arrays.stream(Month.values())
+        .filter(month -> month.name().substring(0, 3).equalsIgnoreCase(abbreviation))
+        .findFirst();
+
+    return monthOptional.orElseThrow(IllegalArgumentException::new).getValue();
+  }
+
+  public static String monthAbbrToFullName(String abbreviation) {
+    Optional<Month> monthOptional = Arrays.stream(Month.values())
+        .filter(month -> month.name().substring(0, 3).equalsIgnoreCase(abbreviation))
+        .findFirst();
+
+    return monthOptional.orElseThrow(IllegalArgumentException::new)
+        .getDisplayName(TextStyle.FULL, Locale.getDefault());
+  }
+
+}

src/main/java/com/howtodoinjava/core/datetime/DayPeriodFormatter.java

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+package com.howtodoinjava.core.datetime;
+
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+
+public class DayPeriodFormatter {
+
+  static LocalTime night = LocalTime.of(21, 0, 0);
+  static LocalTime morning = LocalTime.of(6, 0, 0);
+  static LocalTime afternoon = LocalTime.of(12, 0, 0);
+  static LocalTime evening = LocalTime.of(18, 0, 0);
+  static LocalTime almostMidnight = LocalTime.of(23, 59, 59);
+  static LocalTime midnight = LocalTime.of(0, 0, 0);
+
+  public static void main(String[] args) {
+
+    LocalDateTime localDateTime = LocalDateTime.now();
+
+    System.out.println(DayPeriodFormatter.formatBeforeJava16(localDateTime, ZoneId.systemDefault()));
+    System.out.println(DayPeriodFormatter.formatSinceJava16(localDateTime, ZoneId.systemDefault()));
+  }
+
+  public static String formatBeforeJava16(LocalDateTime localDateTime, ZoneId zoneId) {
+
+    ZonedDateTime zdt = localDateTime.atZone(zoneId);
+    LocalTime lt = zdt.toLocalTime();
+
+    DateTimeFormatter formatter
+        = DateTimeFormatter.ofPattern("yyyy-MMM-dd");
+
+    String dayTime = "";
+
+    if ((lt.isAfter(night) && lt.isBefore(almostMidnight))
+        || lt.isAfter(midnight) && (lt.isBefore(morning))) {
+      dayTime = " at night";
+    } else if (lt.isAfter(morning) && lt.isBefore(afternoon)) {
+      dayTime = " in the morning";
+    } else if (lt.isAfter(afternoon) && lt.isBefore(evening)) {
+      dayTime = " in the afternoon";
+    } else if (lt.isAfter(evening) && lt.isBefore(night)) {
+      dayTime = " in the evening";
+    }
+
+    return zdt.withZoneSameInstant(zoneId).format(formatter) + dayTime;
+  }
+
+  public static String formatSinceJava16(LocalDateTime localDateTime, ZoneId zoneId) {
+
+    ZonedDateTime zdt = localDateTime.atZone(zoneId);
+    DateTimeFormatter formatter
+        = DateTimeFormatter.ofPattern("yyyy-MMM-dd [B]");
+    return zdt.withZoneSameInstant(zoneId).format(formatter);
+  }
+}