Java Program to Display Name of the Weekdays in Calendar Year

Concept: In java when it comes down to the date and time problems after hitting the brute force method one should always remember the Date class of java which not only provides to print current or forthcoming year, month, day, date, time, hour, minutes, and even precision to seconds. Not only one can display these parameters but also can be formatted to display them all in different formats. This class takes a step ahead.

Now in order to display the name of weekdays in a calendar year:

Approaches:

• Using existing Date format class
• Using the brute force approach

Approach 1: Using DateFormat class

It is used to display data and time and manipulate date and time in java and in addition to this it is also used for formatting date, time, week, months, years in java across time zone associated data. 

Note: Epoch time is 1 Jan 1970

 So in order to import this class from a package called java.utils

Syntax:

import java.util.Date ;

After importing this class one can create an object of the Date class in order to print the current date and time. Now in order to print the default date and time simply call the print command using toString() method to get the current date and time. Suppose if the user wants a particular date, time, and month from a current time:

Sample Example: Simple code to clarify the implementation of the date class before moving ahead to displaying the name of weekdays.

Java

// Java Program to Display name of the weekdays in calendar
// year Sample code showing different data class parameters

// Importing Libraries
import java.util.Date;
import java.util.*;

public class GFG {

    // Main driver method
    public static void main(String[] args)
    {

        // Creating an object of Date class- date
        Date date = new Date();

        // Printing date
        System.out.println(date.toString());
        System.out.println(date.getTime());

        // Remember to add 1 to it because this print
        // current month Jan is assigned 0
        System.out.println(date.getMonth() + 1);

        // Remember to add 1 to it because this print
        // epoch year 1970 is set as reference
        system.out.println(date.getYear() + 1900);

        // For week internally it starts with Monday=1
        System.out.println(date.getDay(date));
        // no ambiguity here in displaying week
    }
}

So now if one wants to print date and time in different formats customized date, time, weekdays, years and so on which is the aim of the problem statement. 

1. A class named text is to be imported
2. Then a class is used called- SimpleDateFormat
3. Now after this a method needs to be called format

Syntax:

import java.text.*;

The following Java code illustrates the usage of the invoked inbuilt class :

Java

// Importing generic Classes/Files
import java.io.*;

// Importing specific text class for formatting
//  week via inbuilt function getweek() of data class
import java.text.DateFormatSymbols;
// Dealing with week parameter of data class

class GFG {

    // Main driver method
    public static void main(String[] args)
    {

        // Inbuilt function to invoke weekdays by creating
        // an object of DateFormatSymbols
        String[] week_days
            = new DateFormatSymbols().getWeekdays();

        // Computing length to get end bound
        // for iteration
        int length = week_days.length;

        // Loop is started with 2 because 0th day is
        // saturday and 1st day is sunday
        for (int d = 2; d < (length - 1); d++) {

            // Iterating over the string array of weekdays
            // to get respective names
            String day = week_days[d];

            // Printing ith index weekday
            System.out.println((d - 1) + "th weekday - "
                               + day);
        }
    }
}

Output

1th weekday - Monday
2th weekday - Tuesday
3th weekday - Wednesday
4th weekday - Thursday
5th weekday - Friday

DateFormatSymbols is an in-built class in Java available publicly used for combining various date-time formatting data entities, like the month names, weekdays, and the time zone associated data. DateFormatSymbols are used by SimpleDateFormat to carry out encapsulation of the captured information. This class supports an in-built method getWeekdays() of DateFormatSymbols which is used to retrieve the name of the weekdays of the calendar. All the days are returned in a string format. The method has the following syntax in Java :  

String[] getWeekdays() 

• The method does not accept any arguments or parameters.
• It returns the names of the calendar weekdays in the form of a string array.

Approach 2: Brute force 

There are five weekdays in a calendar, which can be maintained in the form of a string array and simulating a for or while loop iterating over the array containing weekdays or a simple switch case.  

Java

// Importing generic Classes/Files
import java.io.*;

class GFG {

    // Main driver method
    public static void main(String[] args)
    {

        // Creating a list of weekdays
        String[] weekdays
            = { "Monday", "Tuesday", "Wednesday",
                "Thursday", "Friday" };

        // Iterating 5 times only
        // since there are 5 weekdays
        for (int d = 1; d < 6; d++) {

            // Message printing weekdays in calendar year
            System.out.println(d + "th weekday - "
                               + weekdays[d - 1]);
        }
    }
}

Output

1th weekday - Monday
2th weekday - Tuesday
3th weekday - Wednesday
4th weekday - Thursday
5th weekday - Friday