java 核心技术 卷1 第四章 CalendarTest

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();
}

}