Java ChronoLocalDateTime format()方法及示例

Java中ChronoLocalDateTime接口的 format() 方法使用指定的格式化器格式化这个日期时间。

语法

default String format(DateTimeFormatter formatter)

参数。该方法接受一个参数formatter，它指定了要使用的DateTimeFormatter，而不是null。

返回： 该函数返回 格式化的日期字符串 ，而不是null。

以下程序说明了ChronoLocalDateTime.format()方法。

程序1 :

// Java program to illustrate the format() method  import java.util.*;import java.time.*;import java.time.chrono.*;import java.time.format.DateTimeFormatter;  public class GfG {    public static void main(String[] args)    {        // Parses the date        ChronoLocalDateTime dt1            = LocalDateTime                  .parse("2018-11-03T12:45:30");          // Prints the date        System.out.println("Original ChronoLocalDateTime: "                           + dt1);          // Display d1 in different formats        // using format() method        System.out.println("BASIC_ISO_DATE format: "                           + (DateTimeFormatter.BASIC_ISO_DATE)                                 .format(dt1));        System.out.println("ISO_LOCAL_DATE format: "                           + (DateTimeFormatter.ISO_LOCAL_DATE)                                 .format(dt1));        System.out.println("ISO_DATE format: "                           + (DateTimeFormatter.ISO_DATE)                                 .format(dt1));        System.out.println("ISO_LOCAL_TIME format: "                           + (DateTimeFormatter.ISO_LOCAL_TIME)                                 .format(dt1));    }}

输出:

Original ChronoLocalDateTime: 2018-11-03T12:45:30BASIC_ISO_DATE format: 20181103ISO_LOCAL_DATE format: 2018-11-03ISO_DATE format: 2018-11-03ISO_LOCAL_TIME format: 12:45:30

程序2

// Program to illustrate the format() method  import java.util.*;import java.time.*;import java.time.chrono.*;import java.time.format.DateTimeFormatter;  public class GfG {    public static void main(String[] args)    {        // Parses the date        ChronoLocalDateTime dt1            = LocalDateTime                  .parse("2016-09-06T12:45:30");          // Prints the date        System.out.println(dt1);          // Display d1 in different formats        // using format() method        System.out.println("ISO_TIME format: "                           + (DateTimeFormatter.ISO_TIME)                                 .format(dt1));        System.out.println("ISO_LOCAL_DATE_TIME format: "                           + (DateTimeFormatter.ISO_LOCAL_DATE_TIME)                                 .format(dt1));        System.out.println("ISO_DATE_TIME format: "                           + (DateTimeFormatter.ISO_DATE_TIME)                                 .format(dt1));        System.out.println("ISO_ORDINAL_DATE format: "                           + (DateTimeFormatter.ISO_ORDINAL_DATE)                                 .format(dt1));        System.out.println("ISO_WEEK_DATE format: "                           + (DateTimeFormatter.ISO_WEEK_DATE)                                 .format(dt1));    }}

输出:

2016-09-06T12:45:30ISO_TIME format: 12:45:30ISO_LOCAL_DATE_TIME format: 2016-09-06T12:45:30ISO_DATE_TIME format: 2016-09-06T12:45:30ISO_ORDINAL_DATE format: 2016-250ISO_WEEK_DATE format: 2016-W36-2

参考资料: https://docs.oracle.com/javase/9/docs/api/java/time/chrono/ChronoLocalDateTime.html#format-java.time.format.DateTimeFormatter-