calendar type elements in a list
I have to create a program which prints out a list of dates (year, month, days) until a users selected date ( end_date which is later converted to end_cal ).
For example, if today is 2017-09-30 Saturday and user inputs date 2017-10-30 , program must print out these dates:
2017-09-30, 2017-10-07, 2017-10-14, 2017-10-21, 2017-10-28.
Problems:
When I try to print it, output is just a bunch of duplicates of same date.
public class Weekdays {
static Scanner input = new Scanner(System.in);
static Calendar temp_cal = Calendar.getInstance(); //temporary calendar object. it's value is being chaged in the process
static Calendar start_cal = Calendar.getInstance(); // current day when the program is executed
static Calendar end_cal = Calendar.getInstance(); //end date that the user inputs
static SimpleDateFormat format = new SimpleDateFormat("yyyy/MM/dd");
public static boolean date_validation(String date){ //partial validation: whether the input date is in a correct format
Date test_date;
try {
test_date = format.parse(date);
}catch (ParseException e){
return false;
}
return true;
}
//created list of dates that are of the same day of the week (for example all Sundays)
static private List<Calendar> getListOfDates(){
List<Calendar> dates = new ArrayList<>();
while (!((temp_cal.get(Calendar.YEAR)>= end_cal.get(Calendar.YEAR))&&(temp_cal.get(Calendar.MONTH) >= end_cal.get(Calendar.MONTH))&&(temp_cal.get(Calendar.DAY_OF_YEAR) >= end_cal.get(Calendar.DAY_OF_YEAR))))
{
temp_cal.add(Calendar.DATE, 7);
dates.add(temp_cal); }
return dates;
}
static private void printListOfDates(List<Calendar> dates){
System.out.println(Arrays.toString(dates.toArray()));
}
public static void main(String[] str) throws ParseException{
String end_date = input.next();
while(!(date_validation(end_date))){
end_date = input.next();
}
end_cal.setTime(format.parse(end_date));
printListOfDates(getListOfDates());
}
Input: 2018/01/01
Output (copied only one example, whole output is just several duplicates of this):
java.util.GregorianCalendar[time=1515233525518,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Europe/Helsinki",offset=7200000,dstSavings=3600000,useDaylight=true,transitions=118,lastRule=java.util.SimpleTimeZone[id=Europe/Helsinki,offset=7200000,dstSavings=3600000,useDaylight=true,startYear=0,startMode=2,startMonth=2,startDay=-1,startDayOfWeek=1,startTime=3600000,startTimeMode=2,endMode=2,endMonth=9,endDay=-1,endDayOfWeek=1,endTime=3600000,endTimeMode=2]],firstDayOfWeek=2,minimalDaysInFirstWeek=4,ERA=1,YEAR=2018,MONTH=0,WEEK_OF_YEAR=1,WEEK_OF_MONTH=1,DAY_OF_MONTH=6,DAY_OF_YEAR=6,DAY_OF_WEEK=7,DAY_OF_WEEK_IN_MONTH=1,AM_PM=1,HOUR=0,HOUR_OF_DAY=12,MINUTE=12,SECOND=5,MILLISECOND=518,ZONE_OFFSET=7200000,DST_OFFSET=0]]
I'm not sure if this is the correct format for you (I will leave that as a task for you) but you could do something like this using LocalDate :
import java.util.Scanner;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy/MM/dd");
LocalDate endDate;
while(true){
System.out.print("Enter the endDate in the format of yyyy/MM/dd:");
String date = scanner.next();
try {
endDate = LocalDate.parse(date, formatter);
break;
} catch (Exception e) {
System.err.println("ERROR: Please input the date in the correct format");
}
}
System.out.println("Below are the days between the current day and " + endDate);
printDaysBetween(endDate);
}
public static void printDaysBetween(LocalDate end){
LocalDate start = LocalDate.now();
while (!start.isAfter(end)) {
System.out.println(start);
start = start.plusDays(7);
}
}
}
Example Usage:
Enter the endDate in the format of yyyy/MM/dd: 2017-10-30
ERROR: Please input the date in the correct format
Enter the endDate in the format of yyyy/MM/dd: 2017/10/30
Below are the days between the current day and 2017-10-30
2017-09-30
2017-10-07
2017-10-14
2017-10-21
2017-10-28
The first issue is with the way you print out the result:
System.out.println(Arrays.toString(dates.toArray()));
If you want formatted dates, you will need to make use of a formatter.
private static SimpleDateFormat outputFormat = new SimpleDateFormat("yyyy-MM-dd");
static private void printListOfDates(List<Calendar> dates){
for (Calendar date : dates) {
System.out.println(outputFormat.format(date));
}
}
A second issue is that you seem to reuse the same temp_cal object in your loop in getListOfDates. This results in your list containing multiple copies of the same Calendar object (which is modified multiple times). You will need to create a new instance for every iteration in your loop.
import java.util.Date;
import java.time.*;
import java.text.SimpleDateFormat;
import java.util.*;
public class days
{
public static void main (String args[]){
Scanner input = new Scanner(System.in);
System.out.println("Enter Dates (Start(yyyy/mm/dd)-End)");
//example 2017 1 5 -> 5 jan 2017
getDates(Integer.parseInt(input.next()),Integer.parseInt(input.next()),
Integer.parseInt(input.next()),Integer.parseInt(input.next()),
Integer.parseInt(input.next()),Integer.parseInt(input.next()));
/*the input needed example
* 2017
* 1
* 1 -Start date
* 2017
* 2
* 10 -End date
*/
}
public static void getDates(int pYearStart, int pMonthStart, int pDayStart,
int pYearEnd, int pMonthEnd, int pDayEnd){
SimpleDateFormat sdf = new SimpleDateFormat("yyyy MMM dd");
int year = pYearStart;
int month = pMonthStart-1;
int day = pDayStart;
Calendar start = new GregorianCalendar(year,month,day);
int yearEnd = pYearEnd;
int monthEnd = pMonthEnd-1;
int dayEnd = pDayEnd;
Calendar end = new GregorianCalendar(yearEnd,monthEnd,dayEnd);
System.out.print("Start Date: ");
System.out.println(sdf.format(start.getTime()));
System.out.print("End Date: ");
System.out.println(sdf.format(end.getTime()));
System.out.println("");
System.out.println("All Dates:");
boolean sameDate = false;
int amount = 0;
do{
System.out.println(sdf.format(start.getTime()));
start.add(Calendar.DAY_OF_MONTH, 7);
amount++;
if(start.get(Calendar.DAY_OF_MONTH) >= end.get(Calendar.DAY_OF_MONTH) &&
start.get(Calendar.MONTH) == end.get(Calendar.MONTH)) {
sameDate = true;}
}while(sameDate != true);
System.out.println("No of dates: "+amount);
}
}
我认为这就是你想要的，我没有使用列表，只是改变它，只要你喜欢。
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