java 核心技术卷1 第四章 CalendarTest

最新推荐文章于 2023-01-01 21:36:27 发布

原创最新推荐文章于 2023-01-01 21:36:27 发布 · 1k 阅读

0 ·

CC 4.0 BY-SA版权

Java 专栏收录该内容

75 篇文章

订阅专栏

本文展示了如何使用Java的GregorianCalendar和Calendar类进行日期操作，包括获取当前月份的天数、找出月份的第一天、打印周几的名字以及标记当前日期等。通过示例代码详细解释了如何在Java中处理日期和星期的转换与打印。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

package char04;

import java.text.DateFormatSymbols;
import java.util.Calendar;
import java.util.GregorianCalendar;

public class CalendarTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		GregorianCalendar d =new GregorianCalendar();
		int today=d.get(Calendar.DAY_OF_MONTH);
		int month=d.get(Calendar.MONTH);
		//set d to start date of the month
		d.set(Calendar.DAY_OF_MONTH, 1);
		int weekday=d.get(Calendar.DAY_OF_WEEK);
		System.out.println("weekday="+weekday);
		
		//get first day of week(Sunday in the U.S.)
		int firstDayOfWeek=d.getFirstDayOfWeek();
		//determine the required indentation for the first line
		int indent=0;
		while(weekday!=firstDayOfWeek){
			indent++;
			d.add(Calendar.DAY_OF_MONTH, -1);
			weekday=d.get(Calendar.DAY_OF_WEEK);
		}
		//print weekday names
		String[] weekdayNames=new DateFormatSymbols().getShortWeekdays();
		do{
			System.out.printf("%4s",weekdayNames[weekday]);
			d.add(Calendar.DAY_OF_MONTH, 1);
			weekday=d.get(Calendar.DAY_OF_WEEK);
		}while(weekday!=firstDayOfWeek);
		System.out.println();
		
		for(int i=1;i<=indent;i++){
			System.out.print("   ");
		}
		
		d.set(Calendar.DAY_OF_MONTH, 1);
		do{
			//print day
			int day=d.get(Calendar.DAY_OF_MONTH);
			System.out.printf("%3d",day);
			//mark current day with *
			if(day==today)System.out.print("*");
			else System.out.print(" ");
			//advance d to the next day
			d.add(Calendar.DAY_OF_MONTH, 1);
			weekday=d.get(Calendar.DAY_OF_WEEK);
			//start  a new line at the start of the week
			if(weekday==firstDayOfWeek)System.out.println();
		}while(d.get(Calendar.MONTH)==month);
		//the loop exits when d is day 1 of the next month
		//print final end of  line if necessary
		if(weekday!=firstDayOfWeek)System.out.println();
	}

}