Java Calendar clear()方法
java.util.Calendar.clear()方法设置给定的日历字段值，并且未定义此Calendar的时间值。 Calendar实现类可以使用默认字段值进行日期和时间计算。
语法
public final void clear(int field)
参数
field-要设置为未定义的日历字段。
返回
此方法不返回任何值。
抛出
NA
示例1
import java.util.Calendar;
public class CalendarClearExample1 {
public static void main(String[] args) {
// create a calendar
Calendar cal = (Calendar) Calendar.getInstance();
// display the current date and time
System.out.println("Current Calendar Date: " + cal.getTime());
// use clear method to set year as undefined.
cal.clear(Calendar.YEAR);
// print the result
System.out.println("The calendar shows : " + cal.getTime());
}
}
输出:
Current Calendar Date: Mon Jul 30 06:35:54 PDT 2018
The calendar shows : Thu Jul 30 06:35:54 PDT 1970
示例2
import java.util.Calendar;
public class CalendarclearExample2 {
public static void main(String[] args) {
// create a calendar
Calendar cal = (Calendar) Calendar.getInstance();
// display the current date and time
System.out.println("Current Calendar Date: " + cal.getTime());
// use clear method to set month as undefined.
cal.clear(Calendar.MONTH);
// print the result
System.out.println("The calendar shows : " + cal.getTime());
}
}
输出:
Current Calendar Date: Mon Jul 30 06:39:17 PDT 2018
The calendar shows : Tue Jan 30 06:39:17 PST 2018
示例3
import java.util.Calendar;
public class CalendarClearExample3 {
public static void main(String[] args) {
// create a calendar
Calendar cal = (Calendar) Calendar.getInstance();
// display the current date and time
System.out.println("Current Calendar Date: " + cal.getTime());
// use clear method to set month as undefined.
cal.clear(Calendar.DAY_OF_MONTH);
// print the result
System.out.println("The calendar shows : " + cal.getTime());
cal.clear(Calendar.HOUR);
cal.clear(Calendar.MINUTE);
cal.clear(Calendar.SECOND);
// print the result
System.out.println("The calendar shows : " + cal.getTime());
}
}
输出:
Current Calendar Date: Mon Jul 30 06:45:15 PDT 2018
The calendar shows : Mon Jul 30 06:45:15 PDT 2018
The calendar shows : Mon Jul 30 06:00:00 PDT 2018
示例4
import java.util.Calendar;
public class CalendarClearExample4 {
public static void main(String[] args) {
// create a calendar
Calendar cal = (Calendar) Calendar.getInstance();
// display the current date and time
System.out.println("Current Calendar Date: " + cal.getTime());
cal.clear(Calendar.HOUR);
cal.clear(Calendar.MINUTE);
cal.clear(Calendar.SECOND);
// print the result
System.out.println("The calendar shows : " + cal.getTime());
}
}
输出:
Current Calendar Date: Mon Jul 30 06:48:47 PDT 2018
The calendar shows : Mon Jul 30 06:00:00 PDT 2018
