Java Calendar Class用法及代码示例

Java中的Calendar类是一个抽象类，它提供了在特定时间点和一组日历字段(如MONTH、YEAR、HOUR等)之间转换日期的方法。它继承Object类并实现Comparable、Serializable、Cloneable接口。

由于它是一个抽象类，所以我们不能使用构造函数来创建实例。相反，我们必须使用静态方法 Calendar.getInstance() 来实例化并实现sub-class。

Calendar.getInstance()：返回基于默认时区、默认区域设置的当前时间的 Calendar 实例。
Calendar.getInstance(时区)
Calendar.getInstance(区域设置 aLocale)
Calendar.getInstance(TimeZone zone, Locale aLocale)

Java程序演示getInstance()方法：


// Date getTime(): It is used to return a 
// Date object representing this 
// Calendar's time value. 
  
import java.util.*; 
public class Calendar1 { 
    public static void main(String args[]) 
    { 
        Calendar c = Calendar.getInstance(); 
        System.out.println("The Current Date is:" + c.getTime()); 
    } 
}

输出：

The Current Date is:Tue Aug 28 11:10:40 UTC 2018

Important Methods and their usage

METHOD	DESCRIPTION
抽象无效添加(int字段，int数量)	它用于根据日历的规则向给定日历字段添加或减去指定的时间量。
int get(int 字段)	它用于返回给定日历字段的值。
摘要 int getMaximum(int 字段)	它用于返回此 Calendar 实例的给定日历字段的最大值。
摘要 int getMinimum(int 字段)	它用于返回此 Calendar 实例的给定日历字段的最小值。
日期getTime()	它用于返回表示此日历的时间值的 Date 对象。</td

以下示例程序旨在说明上述方法：

程序1:：Java程序演示get()方法。


// Program to demonstrate get() method 
// of Calendar class 
  
import java.util.*; 
public class Calendar2 { 
    public static void main(String[] args) 
    { 
        // creating Calendar object 
        Calendar calendar = Calendar.getInstance(); 
          
        // Demonstrate Calendar's get()method 
        System.out.println("Current Calendar's Year: " + calendar.get(Calendar.YEAR)); 
        System.out.println("Current Calendar's Day: " + calendar.get(Calendar.DATE)); 
        System.out.println("Current MINUTE: " + calendar.get(Calendar.MINUTE)); 
        System.out.println("Current SECOND: " + calendar.get(Calendar.SECOND)); 
    } 
}

输出：

Current Calendar's Year: 2018
Current Calendar's Day: 28
Current MINUTE: 10
Current SECOND: 45

程序2:：Java程序演示getMaximum()方法。


// Program to demonstrate getMaximum() method 
// of Calendar class 
  
import java.util.*; 
public class Calendar3 { 
    public static void main(String[] args) 
    { 
        // creating calendar object 
        Calendar calendar = Calendar.getInstance(); 
      
        int max = calendar.getMaximum(Calendar.DAY_OF_WEEK); 
        System.out.println("Maximum number of days in a week: " + max); 
          
        max = calendar.getMaximum(Calendar.WEEK_OF_YEAR); 
        System.out.println("Maximum number of weeks in a year: " + max); 
    } 
}

输出：

Maximum number of days in a week: 7
Maximum number of weeks in a year: 53

程序3:：Java程序演示getMinimum()方法。


// Program to demonstrate getMinimum() method 
// of Calendar class 
  
import java.util.*; 
public class Calendar4 { 
    public static void main(String[] args) 
    { 
        // creating calendar object 
        Calendar calendar = Calendar.getInstance(); 
          
        int min = calendar.getMinimum(Calendar.DAY_OF_WEEK); 
        System.out.println("Minimum number of days in week: " + min); 
          
        min = calendar.getMinimum(Calendar.WEEK_OF_YEAR); 
        System.out.println("Minimum number of weeks in year: " + min); 
    } 
}

输出：

Minimum number of days in week: 1
Minimum number of weeks in year: 1

程序4:：Java程序演示add()方法。


// Program to demonstrate add() method 
// of Calendar class 
  
import java.util.*; 
public class Calendar5 { 
    public static void main(String[] args) 
    { 
        // creating calendar object 
        Calendar calendar = Calendar.getInstance(); 
        calendar.add(Calendar.DATE, -15); 
        System.out.println("15 days ago: " + calendar.getTime()); 
        calendar.add(Calendar.MONTH, 4); 
        System.out.println("4 months later: " + calendar.getTime()); 
        calendar.add(Calendar.YEAR, 2); 
        System.out.println("2 years later: " + calendar.getTime()); 
    } 
}

输出：

15 days ago: Mon Aug 13 11:10:57 UTC 2018
4 months later: Thu Dec 13 11:10:57 UTC 2018
2 years later: Sun Dec 13 11:10:57 UTC 2020

参考： https://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html

相关用法

注：本文由纯净天空筛选整理自Poojitha Reddy 1大神的英文原创作品 Calendar Class 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。