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📜  Java8 LocalDateTime类

📅  最后修改于: 2020-10-01 06:37:10             🧑  作者: Mango

Java LocalDateTime类

Java LocalDateTime类是一个不可变的日期时间对象，代表日期时间，其默认格式为yyyy-MM-dd-HH-mm-ss.zzz。它继承了对象类并实现了ChronoLocalDateTime接口。

Java LocalDateTime类声明

我们来看一下java.time.LocalDateTime类的声明。

public final class LocalDateTime extends Object 
implements Temporal, TemporalAdjuster, ChronoLocalDateTime, Serializable

Java LocalDateTime的方法

Method Description
String format(DateTimeFormatter formatter) It is used to format this date-time using the specified formatter.
int get(TemporalField field) It is used to get the value of the specified field from this date-time as an int.
LocalDateTime minusDays(long days) It is used to return a copy of this LocalDateTime with the specified number of days subtracted.
static LocalDateTime now() It is used to obtain the current date-time from the system clock in the default time-zone.
static LocalDateTime of(LocalDate date, LocalTime time) It is used to obtain an instance of LocalDateTime from a date and time.
LocalDateTime plusDays(long days) It is used to return a copy of this LocalDateTime with the specified number of days added.
boolean equals(Object obj) It is used to check if this date-time is equal to another date-time.

Java LocalDateTime示例

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class LocalDateTimeExample1 {
    public static void main(String[] args) {
        LocalDateTime now = LocalDateTime.now();
        System.out.println("Before Formatting: " + now);
        DateTimeFormatter format = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss");
        String formatDateTime = now.format(format);
        System.out.println("After Formatting: " + formatDateTime);
    }
}

输出：

Before Formatting: 2017-01-13T17:09:42.411
After Formatting: 13-01-2017 17:09:42

Java LocalDateTime示例：now()

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class LocalDateTimeExample2 {
  public static void main(String[] args) {
    LocalDateTime datetime1 = LocalDateTime.now();
    DateTimeFormatter format = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss");
    String formatDateTime = datetime1.format(format); 
    System.out.println(formatDateTime);  
  }
}

输出：

14-01-2017 11:42:32

Java LocalDateTime示例：get()

import java.time.LocalDateTime;
import java.time.temporal.ChronoField;
public class LocalDateTimeExample3 {
  public static void main(String[] args) {
    LocalDateTime a = LocalDateTime.of(2017, 2, 13, 15, 56);  
    System.out.println(a.get(ChronoField.DAY_OF_WEEK));
    System.out.println(a.get(ChronoField.DAY_OF_YEAR));
    System.out.println(a.get(ChronoField.DAY_OF_MONTH));
    System.out.println(a.get(ChronoField.HOUR_OF_DAY));
    System.out.println(a.get(ChronoField.MINUTE_OF_DAY)); 
  }
}

输出：

1
44
13
15
956

Java LocalDateTime示例：minusDays()

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class LocalDateTimeExample4 {
public static void main(String[] args) {
  LocalDateTime datetime1 = LocalDateTime.of(2017, 1, 14, 10, 34);
  LocalDateTime datetime2 = datetime1.minusDays(100);
  System.out.println("Before Formatting: " + datetime2);
  DateTimeFormatter format = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm");
  String formatDateTime = datetime2.format(format); 
  System.out.println("After Formatting: " + formatDateTime );
}
}

输出：

Before Formatting: 2016-10-06T10:34
After Formatting: 06-10-2016 10:34

Java LocalDateTime示例：plusDays()

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class LocalDateTimeExample5 {
public static void main(String[] args) {
  LocalDateTime datetime1 = LocalDateTime.of(2017, 1, 14, 10, 34);
  LocalDateTime datetime2 = datetime1.plusDays(120);
  System.out.println("Before Formatting: " + datetime2);
  DateTimeFormatter format = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm");
  String formatDateTime = datetime2.format(format); 
  System.out.println("After Formatting: " + formatDateTime );
}
}

输出：

Before Formatting: 2017-05-14T10:34
After Formatting: 14-05-2017 10:34