## Problem Description :

Write a program in Java that checks whether given date occurred on Friday 13th or not?

## Concept :

In this problem we need to check day name and day number (in month) of given date. Day name should be Friday and day number should be 13. The solution is very simple and straightforward. With the help of DAY_OF_WEEK and DAY_OF_MONTH constants of Calendar class that is present in java.util.* package we can easily solve this problem.

## Java Program :

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 Problems
* @level medium
* @problem How to check whether given date occured on 13th Friday?
*
*/
public class CheckDateOccurendOnFriday13th {

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);
// calendar.get(Calendar.DAY_OF_WEEK)==6 (Friday)
if (calendar.get(Calendar.DAY_OF_WEEK) == 6 && calendar.get(Calendar.DAY_OF_MONTH) == 13) {
System.out.println("Given date occured on Friday the 13th.");
} else {
System.out.println("Given date not occured on Friday the 13th.");
}

} 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 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 :

### Case 1 :

 Output - Given date not occurred on Friday the 13th

### Case 2 :

 Output - Given date occurred on Friday the 13th

## Similar Problems :

1) How to check whether given date occurred on Sunday Xth in Java?

- Replace line 35 with  if (calendar.get(Calendar.DAY_OF_WEEK) == 1 && calendar.get(Calendar.DAY_OF_MONTH) == X) {

2) How to check whether given date occurred on Monday Xth in Java?

Replace line 35 with  if (calendar.get(Calendar.DAY_OF_WEEK) == 2 && calendar.get(Calendar.DAY_OF_MONTH) == X) {

3) How to check whether given date occurred on Tuesday Xth in Java?

Replace line 35 with  if (calendar.get(Calendar.DAY_OF_WEEK) == 3 && calendar.get(Calendar.DAY_OF_MONTH) == X) {

4) How to check whether given date occurred on Wednesday Xth in Java?

Replace line 35 with  if (calendar.get(Calendar.DAY_OF_WEEK) == 4 && calendar.get(Calendar.DAY_OF_MONTH) == X) {

5) How to check whether given date occurred on Thursday Xth in Java?

Replace line 35 with  if (calendar.get(Calendar.DAY_OF_WEEK) == 5 && calendar.get(Calendar.DAY_OF_MONTH) == X) {

6) How to check whether given date occurred on Saturday Xth in Java?

Replace line 35 with  if (calendar.get(Calendar.DAY_OF_WEEK) == 7 && calendar.get(Calendar.DAY_OF_MONTH) == X) {

## 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, DateFormat, SimpleDateFormat, String, Calendar, if else statement.