How do I add n days to a date in Java Creating my own java class?
For example, my date is (dd/mm/yyyy) = 26/02/2014
Adding 3 days, the output should be 01/03/2014.
Without importing Calendar or Date from JAVA API
Thank you in Advance. Any Sample code or Pseudo Code or idea will be highly apprecited
Convert the date to days. For example how many days passed from 01/01/1900 then add 3 days and convert it back.
This was one of my interview question, I had return the below code on paper may be my bad luck :-( I didn't get selected in that round, may be interviewer was not able to understand :-) :-). I just searched to see is there any better way of doing it but I didn't, so I wrote same code what I had written on paper but its working like charm. Hope fully my confidence remains same :-) :-)
Hope this help you or some body.
import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;
public class MyDate
{
private static final Map<Integer, Integer> daysInMonth;
static
{
daysInMonth = new HashMap<Integer, Integer>();
daysInMonth.put(1, 31);
daysInMonth.put(2, 28);
daysInMonth.put(3, 31);
daysInMonth.put(4, 30);
daysInMonth.put(5, 31);
daysInMonth.put(6, 30);
daysInMonth.put(7, 31);
daysInMonth.put(8, 31);
daysInMonth.put(9, 30);
daysInMonth.put(10, 31);
daysInMonth.put(11, 30);
daysInMonth.put(12, 31);
}
private int day;
private int month;
private int year;
private int amount;
public MyDate(int day, int month, int year)
{
this.day = day;
this.month = month;
this.year = year;
}
public MyDate addOrSubDays(int amount)
{
this.amount = amount;
return addOrSubDays(this.day + this.amount, this.month, this.year);
}
public static void main(String[] args)
{
int amount = 650;
MyDate myDate = new MyDate(21, 5, 2016);
MyDate addOrSubDays = myDate.addOrSubDays(amount);
System.out.println(addOrSubDays.getDay() + "-" + addOrSubDays.getMonth() + "-" + addOrSubDays.getYear());
// Testing
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DAY_OF_MONTH, amount);
System.out.println(cal.getTime());
}
private MyDate addOrSubDays(int days, int month, int year)
{
if (days > 0 && days <= getNoOfDaysInMonth(month, year))
{
return new MyDate(days, month, year);
}
else if (days <= 0)
{
month = month - 1;
if (month == 0)
{
month = 12;
year = year - 1;
}
days = getNoOfDaysInMonth(month, year) + days;
}
else
{
month = month + 1;
if (month > 12)
{
month = 1;
year = year + 1;
}
days = days - getNoOfDaysInMonth(month, year);
}
return addOrSubDays(days, month, year);
}
private int getNoOfDaysInMonth(int month, int year)
{
if (month == 2 && checkIsLeepYear(year))
{
return daysInMonth.get(month) + 1;
}
return daysInMonth.get(month);
}
private boolean checkIsLeepYear(int year)
{
if ((year % 400 == 0) || ((year % 4 == 0) && (year % 100 != 0)))
{
return true;
}
return false;
}
public int getDay()
{
return day;
}
public int getMonth()
{
return month;
}
public int getYear()
{
return year;
}
public int getAmount()
{
return amount;
}
}
Since everyone is putting their Date class here, I'll post mine.
Here are test results.
Jun 12, 2014 + 10 days -> Jun 22, 2014
Jun 12, 2014 + 20 days -> Jul 2, 2014
Dec 15, 2014 + 20 days -> Jan 4, 2015
Dec 15, 1955 + 30 days -> Jan 14, 1956
Dec 15, 1955 - 30 days -> Nov 15, 1955
Dec 15, 1955 + 16 days -> Dec 31, 1955
Dec 15, 1955 + 17 days -> Jan 1, 1956
Dec 15, 1955 + 80 days -> Mar 4, 1956
Dec 15, 1956 + 80 days -> Mar 5, 1957
Mar 5, 1957 - 80 days -> Dec 15, 1956
Mar 5, 1956 - 80 days -> Dec 16, 1955
And here's the code. I formatted my dates in a month, day, year format. You can change the getFormattedOutput method to be in a day, month, year format.
package com.ggl.testing;
import java.security.InvalidParameterException;
public class Date {
private static final boolean DEBUG = false;
private static final int BASE_MONTH = 1;
private static final int BASE_YEAR = 1700;
private int days;
public Date(int month, int day, int year) {
setDate(month, day, year);
}
public void setDate(int month, int day, int year) {
if ((month >= 1) && (month <= 12)) {
} else {
String s = "Month not between 1 and 12";
throw new InvalidParameterException(s);
}
if (year >= BASE_YEAR) {
int temp = calculateMonthDays(month, year);
if ((day >= 1) && (day <= temp)) {
} else {
String s = "Day not between 1 and " + temp;
throw new InvalidParameterException(s);
}
int days = calculateYearDays(year);
if (DEBUG) {
System.out.println(days);
System.out.println(temp);
}
days += temp;
this.days = days + day;
if (DEBUG) {
System.out.println(day);
System.out.println(this.days);
}
} else {
String s = "Year before " + BASE_YEAR;
throw new InvalidParameterException(s);
}
}
public int[] getDate() {
int days = this.days;
if (DEBUG)
System.out.println(days);
int year = BASE_YEAR;
int decrement = daysInYear(year);
while (days > decrement) {
days -= decrement;
decrement = daysInYear(++year);
}
if (DEBUG)
System.out.println(days);
int month = BASE_MONTH;
decrement = daysInMonth(month, year);
while (days > decrement) {
days -= decrement;
decrement = daysInMonth(++month, year);
}
if (DEBUG)
System.out.println(days);
int day = days;
int[] result = new int[3];
result[0] = month;
result[1] = day;
result[2] = year;
return result;
}
public String getFormattedDate() {
String[] months = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul",
"Aug", "Sep", "Oct", "Nov", "Dec" };
int[] fields = getDate();
return String.format("%s %d, %d", months[fields[0] - 1], fields[1],
fields[2]);
}
public void addDays(int increment) {
this.days += increment;
}
private int calculateMonthDays(int month, int year) {
int days = 0;
for (int i = BASE_MONTH; i < month; i++) {
days += daysInMonth(i, year);
}
return days;
}
private int calculateYearDays(int year) {
int days = 0;
for (int i = BASE_YEAR; i < year; i++) {
days += daysInYear(i);
}
return days;
}
private int daysInMonth(int month, int year) {
int[] days = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
if (month == 2) {
if (daysInYear(year) > 365) {
return days[month - 1] + 1;
}
}
return days[month - 1];
}
private int daysInYear(int year) {
int days = 365;
if ((year % 4) == 0) {
if ((year % 100) == 0) {
if ((year % 400) == 0) {
days++;
}
} else {
days++;
}
}
return days;
}
public static void main(String[] args) {
Date date = new Date(6, 12, 2014);
displayResult(date, 10);
date = new Date(6, 12, 2014);
displayResult(date, 20);
date = new Date(12, 15, 2014);
displayResult(date, 20);
date = new Date(12, 15, 1955);
displayResult(date, 30);
date = new Date(12, 15, 1955);
displayResult(date, -30);
date = new Date(12, 15, 1955);
displayResult(date, 16);
date = new Date(12, 15, 1955);
displayResult(date, 17);
date = new Date(12, 15, 1955);
displayResult(date, 80);
date = new Date(12, 15, 1956);
displayResult(date, 80);
date = new Date(3, 5, 1957);
displayResult(date, -80);
date = new Date(3, 5, 1956);
displayResult(date, -80);
}
private static void displayResult(Date date, int increment) {
String sign = "";
int display = 0;
if (increment > 0) {
sign = " + ";
display = increment;
} else {
sign = " - ";
display = -increment;
}
System.out
.print(date.getFormattedDate() + sign + display + " days -> ");
date.addDays(increment);
System.out.println(date.getFormattedDate());
}
}
try this
class Date {
static int[] daysInMonth = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
int m;
int d;
int y;
Date(String date) {
// parse and get int fields
}
Date(int d, int m, int y) {
this.d = d;
this.m = m;
this.y = y;
}
int maxDays() {
int md = daysInMonth[m - 1];
// correction for Feb
return md;
}
Date addDays(int n) {
int d = this.d += n;
int m = this.m;
int y = this.y;
while (d > maxDays()) {
d = d - maxDays();
m++;
if (m > 12) {
y++;
m = 1;
}
}
return new Date(d, m, y);
}
}
note that code may need fixing
class DateCalculator{
private int[] normalYear = {31,28,31,30,31,30,31,31,30,31,30,31};
private int[] leapYear = {31,29,31,30,31,30,31,31,30,31,30,31};
public String calculateDate(String date, int numberOfDays){
String[] date_parts = date.split("/");
int year = Integer.parseInt(date_parts[2]);
int month = Integer.parseInt(date_parts[1]);
int day = Integer.parseInt(date_parts[0]);
int days = numberOfDays;
int[] refYear = getRefYear(year);
while(true){
int diff = days - (refYear[month - 1] - day);
if(diff > 0 ){
days = diff;
month++;
day = 0;
if(month <= 12){
continue;
}
}else{
day = day + days;
break;
}
year++;
month = 1;
refYear = getRefYear(year);
}
StringBuilder finalDate = new StringBuilder();
finalDate.append(day);
finalDate.append("/");
finalDate.append(month);
finalDate.append("/");
finalDate.append(year);
return finalDate.toString();
}
private int[] getRefYear(int year){
return isLeapYear(year)? leapYear : normalYear;
}
private boolean isLeapYear(int year){
if((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0) ){
return true;
}
return false;
}
}
Question: increase or update given date by certain days, without using calendar or date class?
Answer: I verified first ex and that seems like good a reference for storing values in maps (as days for months are fixed).
My solution is below and it is working correctly, when I tested.
Solution code:
import java.util.*;
public class IncreaseDate {
private static final Map<Integer, Integer> date;
static {
date= new HashMap<Integer,Integer>();
date.put(1,31);
date.put(2,28);
date.put(3,31);
date.put(4,30);
date.put(5,31);
date.put(6,30);
date.put(7,31);
date.put(8,31);
date.put(9,30);
date.put(10,31);
date.put(11,30);
date.put(12,31);
}
public static void main(String args[]) {
IncreaseDate id= new IncreaseDate();
System.out.println("2/5/2018 "+"+"+60+" : ");
id.updateDate(2,5,2018,60);
}
public void updateDate(int m,int d, int y, int days) {
int temp=date.get(m);
// for finding leap year
if(m==2 && (y%4==0 && y%100!=0 && y%400!=0)) {
temp= date.get(m)+1;
}
if(d+days>temp) {
if(m<=11) {
updateDate(m+1,d,y,days-temp);
}
else {
updateDate(1,d,y+1,days-temp);
}
}
else {
System.out.println("Upadate Date: "+m+"/"+(d+days)+"/"+y);
}
}
}
Points to remember:
package StringProgram;
public class AddingDaystoDate {
public static String addDays(String date, int n)
{
int[] daysInNormalYear={31,28,31,30,31,30,31,31,30,31,30,31};
int[] daysInLeapYear={31,29,31,30,31,30,31,31,30,31,30,31};
String[] sArray=date.split("/");
int dd=Integer.valueOf(sArray[0]);
int mm=Integer.valueOf(sArray[1]);
int yy=Integer.valueOf(sArray[2]);
String updatedDate="";
if(calculateLeapYear(yy)==true)
{
int maxDayinMonth=daysInLeapYear[mm-1];
dd=dd+n;
if(dd>maxDayinMonth)
{
dd=dd-maxDayinMonth;
mm++;
if(mm>12)
{
yy++;
mm=1;
}
}
updatedDate=new String(""+dd+"/"+mm+"/"+yy);
}
else
{
int maxDayinMonth=daysInNormalYear[mm-1];
dd=dd+n;
if(dd>maxDayinMonth)
{
dd=dd-maxDayinMonth;
mm++;
if(mm>12)
{
yy++;
mm=1;
}
}
updatedDate=new String(""+dd+"/"+mm+"/"+yy);
}
return updatedDate;
}
public static boolean calculateLeapYear(int year)
{
if(year%4==0)
{
if(year%100==0)
{
if(year%400==0)
{
return true;
}
}
return false;
}
return false;
}
public static void main(String[] args) {
String date="27/12/2014";
String s=addDays(date,5);
System.out.print(s);
}
}
simple code for add or sub using method
public Date1(int d, int m, int y) {
this.day = d;
this.month = m;
this.year = y;
}
public void addDay() {
month--;
Calendar m = Calendar.getInstance();
m.set(year, month, day);
m.add(day, 5); // if you want add or sub month or year it depend on days
java.sql.Date d = new java.sql.Date(m.getTimeInMillis());
DateFormat df = new SimpleDateFormat("dd/MM/yyyy");
System.out.println(" date is " + df.format(d));
