Introduction
In this tutorial, we will be building a simple calendar application using the Java programming language. The app will allow users to add and view events for specific dates in a calendar. This is a beginner-friendly project aimed at helping you understand how to work with Java’s LocalDate and Scanner classes.
Objective
The objective of this program is to create a basic calendar system where users can:
- Add events to specific dates
- View events scheduled for a specific date
Java Code for Calendar App
Below is the complete Java code for our simple Calendar App.
import java.time.LocalDate;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
public class CalendarApp {
private Map<LocalDate, String> events;
public CalendarApp() {
events = new HashMap<>();
}
public void addEvent(LocalDate date, String eventDescription) {
events.put(date, eventDescription);
}
public void viewEvent(LocalDate date) {
if (events.containsKey(date)) {
System.out.println("Event on " + date + ": " + events.get(date));
} else {
System.out.println("No events scheduled for this date.");
}
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
CalendarApp calendar = new CalendarApp();
while (true) {
System.out.println("\n--- Calendar App ---");
System.out.println("1. Add Event");
System.out.println("2. View Event");
System.out.println("3. Exit");
System.out.print("Enter your choice: ");
int choice = scanner.nextInt();
scanner.nextLine(); // Consume newline
switch (choice) {
case 1:
System.out.print("Enter event date (YYYY-MM-DD): ");
String dateInput = scanner.nextLine();
LocalDate eventDate = LocalDate.parse(dateInput);
System.out.print("Enter event description: ");
String description = scanner.nextLine();
calendar.addEvent(eventDate, description);
System.out.println("Event added successfully.");
break;
case 2:
System.out.print("Enter date to view events (YYYY-MM-DD): ");
String viewDateInput = scanner.nextLine();
LocalDate viewDate = LocalDate.parse(viewDateInput);
calendar.viewEvent(viewDate);
break;
case 3:
System.out.println("Exiting the Calendar App. Goodbye!");
scanner.close();
System.exit(0);
break;
default:
System.out.println("Invalid choice, please try again.");
}
}
}
}
Explanation of the Program Structure
This program uses the following components:
- Map<LocalDate, String>: A map to store events where the key is the event’s date and the value is the event description.
- Scanner: This is used to read user input from the console.
- LocalDate: Part of the
java.timepackage, used for working with dates. We use it to handle the date input and manipulation.
How to Run the Program
- Ensure that you have Java installed on your system.
- Create a new file named
CalendarApp.javaand paste the provided Java code into the file. - Open a terminal or command prompt and navigate to the folder where your
CalendarApp.javafile is located. - Compile the Java program by running the following command:
javac CalendarApp.java
- Run the compiled program by executing:
java CalendarApp
- The program will display a simple text-based menu where you can add events and view events by date.
