How to find number of weeks between two given dates in Java?

Problem Description :

Write a program in Java that prints number of weeks between two given dates.

Number of weeks between two given dates

Concept :

For finding number of weeks between two dates, first we have to find total number of days. As we know that 1 week = 7 days, so number of weeks = (total number of days)/7.

Recommended :

How to check whether given date is valid or not?

How to convert String to Date?

How to find number of days between two given dates?

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 weeks between two given dates.
	*
	*/
	public class WeeksBetweenTwoDates {
	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) {
	int days = getNumberofDaysBetweenTwoDates(mydate1, mydate2);
	int weeks = days / 7;
	int remainingDays = days % 7;
	System.out.println(weeks + " Weeks " + remainingDays + " Days");
	} else {
	System.out.println("Dates are invalid.");
	}
	} finally {
	if (input != null) {
	input.close();
	}
	}
	}
	private static int getNumberofDaysBetweenTwoDates(Date mydate1, Date mydate2) {
	/*
	* 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));
	return daysDiff;
	}
	// 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;
	}
	}

view raw WeeksBetweenTwoDates.java hosted with ❤ by GitHub

Output :

Output - How to find number of weeks between two given dates in Java? 

Note : You can also use this calculator for validating your result.

References :

https://docs.oracle.com/javase/7/docs/api/java/util/Date.html

https://docs.oracle.com/javase/7/docs/api/java/util/Date.html#getTime()

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, Weeks between two dates in Java, Solution in Java, DateFormat, SimpleDateFormat, String, Regular expressions, if else statement.

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