Java Clock withZone()用法及代码示例

java.time.Clock.withZone(ZoneId zone)方法是Clock类的一种方法，该方法返回应用了该方法的时钟对象的时钟副本，并带有不同的时区。如果有时钟，并且需要更改时钟区域，但没有其他属性，则使用withZone()方法。此方法将zone作为参数，这是需要更改的时区。它返回带区域的时钟，与参数中传递的区域相同。

用法:

public abstract Clock withZone(ZoneId zone)

参数：此方法采用ZoneId类型的强制性参数区域，在其中需要更改时区。

返回：此方法返回应用了此方法的时钟对象的时钟副本，并以不同的时区作为参数传递。

例：

Code:
//Clock with default zone
Clock clock1=Clock.systemUTC();
ZoneId zone = ZoneId.of("Asia/Calcutta");
Clock clock2 = clock1.withZone(zone);
System.out.println(clock2.toString());

Output::
SystemClock[Asia/Calcutta]

Explanation::
when withZone() is called for Clock object clock1 with zoneId "Asia/Calcutta",
then the withZone() method will return a Clock whose Zone is "Asia/Calcutta".

下面的程序演示了java.time.Clock类的withZone()方法：

程序1:在withZone()的帮助下，创建具有与“第一时钟”相似的属性但zoneId等于“Asia/Calcutta”的时钟。

// Java program to demonstrate 
// withZone() method of Clock class 
  
import java.time.*; 
  
// create class 
public class withZoneMethodDemo { 
  
    // Main method 
    public static void main(String[] args) 
    { 
        // create a base Clock with systemUTC() method 
        Clock baseclock = Clock.systemUTC(); 
  
        // get ZonedDateTime object from baseclock 
        // clock instant to get date time 
        ZonedDateTime baseTime = baseclock 
                                     .instant() 
                                     .atZone(baseclock.getZone()); 
  
        // print details of ZonedDateTime 
        System.out.println("ZonedDateTime of baseclock "
                           + baseTime.toString()); 
  
        // create ZoneId object with Zone Asia/Calcutta 
        ZoneId zone = ZoneId.of("Asia/Calcutta"); 
  
        // apply withZone() to change zone from utc to Asia/Calcutta 
        Clock clockWithOtherZone = baseclock.withZone(zone); 
  
        // get ZonedDateTime object from clockWithOtherZone 
        // clock instant to get date time 
        ZonedDateTime calcuttaTime = clockWithOtherZone 
                                         .instant() 
                                         .atZone(clockWithOtherZone.getZone()); 
  
        // print details of ZonedDateTime 
        System.out.println("ZonedDateTime of clockWithOtherZone "
                           + calcuttaTime.toString()); 
    } 
}

输出：

ZonedDateTime of baseclock 2018-08-24T08:09:17.354Z
ZonedDateTime of clockWithOtherZone 2018-08-24T13:39:17.539+05:30[Asia/Calcutta]

程序2:使用getZone()为withZone()创建的时钟打印zoneId。

// Java program to demonstrate 
// withZone() method of Clock class 
  
import java.time.*; 
  
// create class 
public class withZoneMethodDemo { 
  
    // Main method 
    public static void main(String[] args) 
    { 
        // create a base Clock with systemDefaultZone() method 
        Clock baseclock = Clock.systemDefaultZone(); 
  
        // print details of ZonedDateTime 
        System.out.println("baseclock Zone:"
                           + baseclock.getZone()); 
  
        // create ZoneId object with Zone Asia/Calcutta 
        ZoneId zone = ZoneId.of("Asia/Calcutta"); 
  
        // apply withZone() to change zone 
        // of baseclock to Asia/Calcutta 
        Clock clockWithOtherZone = baseclock.withZone(zone); 
  
        // print details of ZonedDateTime 
        System.out.println("clockWithOtherZone Zone:"
                           + clockWithOtherZone.getZone()); 
    } 
}

输出：

baseclock Zone:Etc/UTC
clockWithOtherZone Zone:Asia/Calcutta

参考：
https://docs.oracle.com/javase/8/docs/api/java/time/Clock.html#withZone-java.time.ZoneId-

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注：本文由纯净天空筛选整理自AmanSingh2210大神的英文原创作品 Java Clock withZone() method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。