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@javamultiplex
Created September 23, 2017 15:09
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How to get Week Day from given Date in Java
package com.javamultiplex.datetime;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Scanner;
/**
*
* @author Rohit Agarwal
* @category Date and Time
* @problem How to get day name of given date?
*
*/
public class GetWeekDayName {
public static void main(String[] args) {
Scanner input = null;
try {
input = new Scanner(System.in);
System.out.println("Enter date in dd/MM/yyyy format :");
String date = input.next();
// If Date is valid, converting String to Date
Date mydate = getValidDate(date);
if (mydate != null) {
// Creating Calendar class instance.
Calendar calendar = Calendar.getInstance();
// Converting Date to Calendar.
calendar.setTime(mydate);
int dayofWeek = calendar.get(Calendar.DAY_OF_WEEK);
String dayName = getDayName(dayofWeek);
System.out.println("Day : " + dayName);
} else {
System.out.println("Date is invalid.");
}
} finally {
if (input != null) {
input.close();
}
}
}
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 String getDayName(int dayofWeek) {
String dayName = null;
switch (dayofWeek) {
case 1:
dayName = "Sunday";
break;
case 2:
dayName = "Monday";
break;
case 3:
dayName = "Tuesday";
break;
case 4:
dayName = "Wednesday";
break;
case 5:
dayName = "Thursday";
break;
case 6:
dayName = "Friday";
break;
case 7:
dayName = "Saturday";
break;
}
return dayName;
}
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;
}
}
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