Problem description :
Write a program in Java that prints number of days between two given dates.
Concept :
We are using below method of Date class that is present in java.util.* package.
public long getTime() -> This method returns the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this Date object. Then we have to convert Milliseconds to Days. I hope everyone is aware of below conversions. Using this we can easily convert Milliseconds to Days.
1 Day = 24 Hours
1 Hour = 60 Minutes
1 Minute = 60 Seconds
1 Second = 1000 Milliseconds
Recommended :
Java Program :
package com.javamultiplex.datetime;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;
/**
*
* @author Rohit Agarwal
* @category Date and Time
* @problem Number of days between two dates
*
*/
public class DaysDifference {
public static void main(String[] args) {
Scanner input = null;
try {
input = new Scanner(System.in);
System.out.println("Enter first date in dd/MM/yyyy format :");
String first = input.next();
System.out.println("Enter second date in dd/MM/yyyy format :");
String second = input.next();
// If Date is valid, converting String to date.
Date mydate1 = getValidDate(first);
Date mydate2 = getValidDate(second);
if (mydate1 != null && mydate2 != null) {
/*
* Calculation for Date 1 We have to convert Milliseconds to
* Days. Step by step we are converting.
*/
long millisecondsInDate1 = mydate1.getTime();
// Converting milliseconds to seconds.
double secondsInDate1 = getSeconds(millisecondsInDate1);
// Converting seconds to minutes.
double minutesInDate1 = getMinutes(secondsInDate1);
// Converting minutes to hours.
double hourInDate1 = getHours(minutesInDate1);
// Converting hours to days.
double daysInDate1 = getDays(hourInDate1);
/*
* Calculation for Date 2 We have to convert Milliseconds to
* Days. Step by step we are converting.
*/
long millisecondsInDate2 = mydate2.getTime();
// Converting milliseconds to seconds.
double secondsInDate2 = getSeconds(millisecondsInDate2);
// Converting seconds to minutes.
double minutesInDate2 = getMinutes(secondsInDate2);
// Converting minutes to hours.
double hourInDate2 = getHours(minutesInDate2);
// Converting hours to days.
double daysInDate2 = getDays(hourInDate2);
int daysDiff = (int) Math.ceil(Math.abs(daysInDate1 - daysInDate2));
System.out.println("Duration between 2 dates : " + daysDiff + " days");
System.out.println("Duration between 2 dates (including end date) : " + (daysDiff + 1) + " days");
} else {
System.out.println("Dates are invalid.");
}
} finally {
if (input != null) {
input.close();
}
}
}
// 1 Second=1000 Milliseconds
private static double getSeconds(long ms) {
double seconds = (double) ms / 1000;
return seconds;
}
// 1 Minute=60 Seconds
private static double getMinutes(double s) {
double minutes = s / 60;
return minutes;
}
// 1 Hour=60 Minutes
private static double getHours(double m) {
double hours = m / 60;
return hours;
}
// 1 Day=24 Hours
private static double getDays(double h) {
double days = h / 24;
return days;
}
private static Date getValidDate(String date) {
Date mydate = null;
if (isValidDateFormat(date)) {
/*
* d -> Day of month
* M -> Month of year
* y -> Year
*/
DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");
/*
* By default setLenient() is true. We should make it false for
* strict date validations.
*
* If setLenient() is true - It accepts all dates. If setLenient()
* is false - It accepts only valid dates.
*/
dateFormat.setLenient(false);
try {
mydate = dateFormat.parse(date);
} catch (ParseException e) {
mydate = null;
}
}
return mydate;
}
private static boolean isValidDateFormat(String date) {
/*
* Regular Expression that matches String with format dd/MM/yyyy.
* dd -> 01-31
* MM -> 01-12
* yyyy -> 4 digit number
*/
String pattern = "(0?[1-9]|[12][0-9]|3[01])\\/(0?[1-9]|1[0-2])\\/([0-9]{4})";
boolean result = false;
if (date.matches(pattern)) {
result = true;
}
return result;
}
}
Output :
Output - How to find number of days between two given dates in Java?
Note : You can also use this calculator for validating your result.
References :
Thank you friends, I hope you have clearly understood the solution of this problem. If you have any doubt, suggestion or query please feel free to comment below. You can also discuss this solution in our forum .
Tags : Date and Time Problems, Days between two dates in Java, Solution in Java, String, DateFormat, SimpleDateFormat, Regular expressions.
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Reviewed by Rohit Agarwal
on
12/09/2016
Rating:
I still can not understand people, who use Java. I remember, that it was popular for more than ten years ago. Though, I may be wrong.
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