Monthly Calender Program in Java

In this blog, I am going to explain about the monthly calendar program in Java.

Introduction

• In this blog, I am going to explain about the monthly calendar program in Java 

Software Requirements

• Java, Notepad.

Program

import java.util.*;
import java.text.*;

public class MonthCalender {

 public final static String[] monthcalender = {
  "January",
  "February",
  "March",
  "April",
  "May",
  "June",
  "July",
  "August",
  "September",
  "October",
  "November",
  "December"
 };

 public final static int daysinmonths[] = {
  31,
  28,
  31,
  30,
  31,
  30,
  31,
  31,
  30,
  31,
  30,
  31
 };

 private void displayMonth(int month, int year) {

  // The number of days to leave blank at
  // the start of this month.

  int blankdays = 0;
  System.out.println("  " + monthcalender[month] + " " + year);

  if (month < 0 || month > 11) {
   throw new IllegalArgumentException(
    "Month " + month + " is not valid and must lie in between 0 and 11");
  }

  GregorianCalendar cldr = new GregorianCalendar(year, month, 1);
  System.out.println("Sunday Monday Tuesday Wednesday Thursday Friday Saturday");

  // Compute how much to leave before before the first day of the month.
  // getDay() returns 0 for Sunday.

  blankdays = cldr.get(Calendar.DAY_OF_WEEK) - 1;
  int daysInMonth = daysinmonths[month];

  if (cldr.isLeapYear(cldr.get(Calendar.YEAR)) && month == 1) {

   ++daysInMonth;
  }

  // Blank out the labels before 1st day of the month
  for (int i = 0; i < blankdays; i++) {
   System.out.print("   ");
  }

  for (int i = 1; i <= daysInMonth; i++) {

   // This "if" statement is simpler than messing with NumberFormat
   if (i <= 9) {
    System.out.print(" ");
   }
   System.out.print(i);

   if ((blankdays + i) % 7 == 0) { // Wrap if EOL
    System.out.println();
   } else {
    System.out.print(" ");
   }
  }
 }

 /**
  * Sole entry point to the class and application.
  * @param args Array of String arguments.
  */
 public static void main(String[] args) {

  int mon, yr;
  MonthCalender moncldr = new MonthCalender();

  if (args.length == 2) {
   moncldr.displayMonth(Integer.parseInt(args[0]) - 1, Integer.parseInt(args[1]));
  } else {
   Calendar todaycldr = Calendar.getInstance();
   moncldr.displayMonth(todaycldr.get(Calendar.MONTH), todaycldr.get(Calendar.YEAR));
  }
 }
}

Output