how to add number of days to the date given in a jtextfield with string data type

Question

Good Day . I just wanna ask about adding days in a given date. I have a jtexfield (txtStart) and another jtexfield(txtExpiry). I need to display in txtExpiry the date after 102

Answer 1

import java.util.*;
class ISCprac2009q01{
public static void main(String args[])
throws InputMismatchException{

Scanner scan=new Scanner(System.in);
System.out.println("ENTER DAY NUMER(>=1 AND
 <=366) : ");
int day_number=scan.nextInt();
System.out.println("ENTER YEAR(4 DIGIT) : ");
int year=scan.nextInt();
System.out.println("ENTER DATE AFTER(N)(>=1 AND
 <=100) : ");
int n=scan.nextInt();

if(day_number<1 || day_number>366)
System.out.println("INVALID DAY NUMBER.");
else if(year<1000 || year >9999)
System.out.println("INVALID YEAR");
else if(n<1 || n>100)
System.out.println("INVALID DATE AFTER VALUE.");
else{
//INITIALIZE MONTH NAMES AND NUMBER OF DAYS IN EACH MONTH
    String month_names[]={"JANUARY", "FEBRUARY","MARCH",
        "APRIL","MAY","JUNE","JULY","AUGUST","SEPTEMBER",
        "OCTOBER","NOVERMBER","DECEMBER"};
    int month_days[]={31,28,31,30,31,30,31,31,30,31,30,31};
    int i, day, month,day_after;
    String suffix;

   //IF IT IS A LEAP YEAR FEBRURAY SHOULD HAVE 29 DAYS
    if(year%400==0 || (year%100!=0 && year%4==0))
        month_days[1]=29;

        i=0;
   //FIND THE DATE CORRESPONDING TO THE DAY NUMBER
        day=day_number;
        while(day>month_days[i])
        {
            day-=month_days[i];
            i++;
        }
        month=i;
        //ADD SUFFIX AS PER THE DAY
        if(day%10==1 && day/10!=1)
            suffix="ST";
        else if(day%10==2 && day/10!=1)
            suffix="ND";
        else if(day%10==3 && day/10!=1)
            suffix="RD";
        else
            suffix="TH";
        System.out.println("OUTPUT:");
        //FIRST PART OF THE OUTPUT
        System.out.println(day+suffix+" "+
        month_names[month]+" "+year);

        //TO CALCULATE DATE AFTER N DAYS
        day_after=day_number+n;
        i=0;
        while(day_after>month_days[i])
        {
            day_after-=month_days[i];
            i++;
            if(i==12){
            i=0;
            year++;
            if(year%400==0 || (year%100!=0 && year%4==0))
                month_days[1]=29;
            }
        }
        day=day_after;
        month=i;
        //ADD SUFFIX AS PER THE DAY
        if(day%10==1 && day/10!=1)
            suffix="ST";
        else if(day%10==2 && day/10!=1)
            suffix="ND";
        else if(day%10==3 && day/10!=1)
            suffix="RD";
        else
            suffix="TH";
       //SECOND PART OF THE OUTPUT
        System.out.println(day+suffix+" "+
        month_names[month]+" "+year);
}
}
}