Converting Calendar, Date, LocalDate, LocalDateTime and Timestamps in Java

» Introduction

Over the years, Java has introduced several packages to deal with any kind of calendar/date/time related stuff. In older and bigger projects, several of those packages may be in use and it can take some work to find a way converting one to another. Here are some helper methods to convert some of them. All of them should be compatible with Java 8.

» Date to Calendar

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public static Calendar toCalendar(Date date) {
   Calendar calendar = Calendar.getInstance();
   calendar.setTime(date);
   return calendar;
}

» LocalDate to Calendar

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public static Calendar toCalendar(LocalDate localDate) {
   Date date = toDate(localDate);
   Calendar calendar = Calendar.getInstance();
   calendar.setTime(date);
   return calendar;
}

» LocalDateTime to Calendar

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public static Calendar toCalendar(LocalDateTime localDateTime) {
   Date date = toDate(localDateTime);
   Calendar calendar = Calendar.getInstance();
   calendar.setTime(date);
   return calendar;
}

» Calendar to Date

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public static Date toDate(Calendar calendar) {
   return calendar.getTime();
}

» LocalDate to Date

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public static Date toDate(LocalDate dateToConvert) {
   return Date.valueOf(dateToConvert);
}

» LocalDateTime to Date

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public static Date toDate(LocalDateTime dateToConvert) {
   return new Date(dateToConvert;
}

» Date to LocalDate

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public static LocalDate toLocalDate(Date dateToConvert) {
   return new Date(dateToConvert.getTime()).toLocalDate();
}

» Date to LocalDateTime

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public static LocalDateTime toLocalDateTime(Date dateToConvert) {
   return new Timestamp(dateToConvert.getTime()).toLocalDateTime();
}

» LocalDate to Timestamp

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public static Timestamp toTimestamp(LocalDate localDate) {
   return Timestamp.valueOf(localDate.atStartOfDay());
}

» LocalDateTime to Timestamp

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public static Timestamp toTimestamp(LocalDateTime localDateTime) {
   return Timestamp.valueOf(localDateTime);
}

» References

… and probably more sources I haven’t written down :-(