Java/Java API の履歴(No.3)

• 履歴一覧
• 差分 を表示
• 現在との差分 を表示
• ソース を表示
• Java/Java API へ行く。
  • 1 (2019-06-15 (土) 16:40:49)
  • 2 (2019-06-15 (土) 17:35:41)
  • 3 (2019-06-15 (土) 23:12:36)
  • 4 (2021-06-16 (水) 15:51:23)
  • 5 (2021-06-23 (水) 17:44:29)

SoftwareEngineering

Java API†

java.time†

LocalDateTime†

truncatedTo メソッド†

• example

  LocalDateTime localDateTime = LocalDateTime.now();
  
  System.out.println("localDateTime                                :" + localDateTime);
  System.out.println("localDateTime.truncatedTo(ChronoUnit.DAYS)   :" + localDateTime.truncatedTo(ChronoUnit.DAYS));
  System.out.println("localDateTime.truncatedTo(ChronoUnit.HOURS)  :" + localDateTime.truncatedTo(ChronoUnit.HOURS));
  System.out.println("localDateTime.truncatedTo(ChronoUnit.MINUTES):" + localDateTime.truncatedTo(ChronoUnit.MINUTES));
  System.out.println("localDateTime.truncatedTo(ChronoUnit.SECONDS):" + localDateTime.truncatedTo(ChronoUnit.SECONDS));
  System.out.println("localDateTime.truncatedTo(ChronoUnit.MILLIS) :" + localDateTime.truncatedTo(ChronoUnit.MILLIS));

• result

  localDateTime                                :2019-06-15T17:35:16.723566900
  localDateTime.truncatedTo(ChronoUnit.DAYS)   :2019-06-15T00:00
  localDateTime.truncatedTo(ChronoUnit.HOURS)  :2019-06-15T17:00
  localDateTime.truncatedTo(ChronoUnit.MINUTES):2019-06-15T17:35
  localDateTime.truncatedTo(ChronoUnit.SECONDS):2019-06-15T17:35:16
  localDateTime.truncatedTo(ChronoUnit.MILLIS) :2019-06-15T17:35:16.723

型変換†

Date => LocalDateTime†

• example

  Date date = new Date();
  LocalDateTime localDateTime = LocalDateTime.ofInstant(date.toInstant(), ZoneId.systemDefault());
  
  System.out.println("date         :" + date);
  System.out.println("localDateTime:" + localDateTime);

• result

  date         :Sat Jun 15 17:51:36 JST 2019
  localDateTime:2019-06-15T17:51:36.151

Date => LocalDate†

• example

  Date date = new Date();
  LocalDateTime localDateTime = LocalDateTime.ofInstant(date.toInstant(), ZoneId.systemDefault());
  LocalDate localDate = localDateTime.toLocalDate();
  
  System.out.println("date         :" + date);
  System.out.println("localDateTime:" + localDateTime);
  System.out.println("localDate    :" + localDate);

• result

  date         :Sat Jun 15 23:08:37 JST 2019
  localDateTime:2019-06-15T23:08:37.014
  localDate    :2019-06-15

LocalDateTime => LocalDate†

• example

  LocalDateTime localDateTime = LocalDateTime.now();
  LocalDate localDate = localDateTime.toLocalDate();
  
  System.out.println("localDateTime:" + localDateTime);
  System.out.println("localDate    :" + localDate);

• result

  localDateTime:2019-06-15T17:51:36.193991600
  localDate    :2019-06-15

LocalDateTime => Date†

• example

  LocalDateTime localDateTime = LocalDateTime.now();
  Date date = Date.from(localDateTime.atZone(ZoneId.systemDefault()).toInstant());
  
  System.out.println("localDateTime:" + localDateTime);
  System.out.println("date         :" + date);

• result

  localDateTime:2019-06-15T23:08:37.015564600
  date         :Sat Jun 15 23:08:37 JST 2019