Java EnumSet add() Method

The EnumSet.add(E e) method in Java is used to add a specified element to an EnumSet. This guide will cover the method's usage with examples, and we will also cover a real-world use case to show how EnumSet.add() can be used effectively.

Table of Contents

1. Introduction
2. add Method Syntax
3. Examples
   • Basic Usage of add Method
   • Adding Multiple Elements
4. Real-World Use Case
   • Example: Managing Selected Days of the Week
5. Conclusion

Introduction

The EnumSet.add(E e) method is a member of the EnumSet class in Java. It allows you to add a specified element to an EnumSet. If the element is already present in the set, the call leaves the set unchanged and returns false.

add() Method Syntax

The syntax for the add method is as follows:

public boolean add(E e)

• Parameters:
  • e: The element to be added to the set.
• Returns: true if the set did not already contain the specified element.

Examples

Basic Usage of add Method

The add method can be used to add an element to an EnumSet.

Example

import java.util.EnumSet;

public class EnumSetAddExample {
    // Define an enum representing days of the week
    enum Day {
        MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY
    }

    public static void main(String[] args) {
        // Creating an empty EnumSet of Day enum
        EnumSet<Day> days = EnumSet.noneOf(Day.class);

        // Adding elements to the EnumSet
        days.add(Day.MONDAY);
        days.add(Day.WEDNESDAY);
        days.add(Day.FRIDAY);

        // Printing the EnumSet
        System.out.println("EnumSet after adding elements: " + days);
    }
}

Output:

EnumSet after adding elements: [MONDAY, WEDNESDAY, FRIDAY]

Adding Multiple Elements

You can add multiple elements to an EnumSet using repeated calls to the add method.

Example

import java.util.EnumSet;

public class EnumSetAddMultipleExample {
    // Define an enum representing types of fruits
    enum Fruit {
        APPLE, BANANA, ORANGE, MANGO, GRAPE
    }

    public static void main(String[] args) {
        // Creating an empty EnumSet of Fruit enum
        EnumSet<Fruit> fruits = EnumSet.noneOf(Fruit.class);

        // Adding multiple elements to the EnumSet
        fruits.add(Fruit.APPLE);
        fruits.add(Fruit.BANANA);
        fruits.add(Fruit.ORANGE);

        // Printing the EnumSet
        System.out.println("EnumSet after adding elements: " + fruits);
    }
}

Output:

EnumSet after adding elements: [APPLE, BANANA, ORANGE]

Real-World Use Case

Example: Managing Selected Days of the Week

A common real-world use case for EnumSet.add() is managing a set of selected days of the week for scheduling or task management.

Example

import java.util.EnumSet;

public class SelectedDaysManager {
    // Define an enum representing days of the week
    enum Day {
        MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY
    }

    public static void main(String[] args) {
        // Creating an empty EnumSet of Day enum
        EnumSet<Day> selectedDays = EnumSet.noneOf(Day.class);

        // Adding selected days to the EnumSet
        selectedDays.add(Day.MONDAY);
        selectedDays.add(Day.WEDNESDAY);
        selectedDays.add(Day.FRIDAY);

        // Printing the selected days
        System.out.println("Selected days: " + selectedDays);

        // Adding a new day
        selectedDays.add(Day.SUNDAY);

        // Printing the updated selected days
        System.out.println("Updated selected days: " + selectedDays);
    }
}

Output:

Selected days: [MONDAY, WEDNESDAY, FRIDAY]
Updated selected days: [MONDAY, WEDNESDAY, FRIDAY, SUNDAY]

In this example, EnumSet.add() is used to manage a set of selected days of the week, making it easy to add new days as needed.

Conclusion

The EnumSet.add(E e) method in Java provides a way to add a specified element to an EnumSet. By understanding how to use this method, you can efficiently manage collections of enum constants. This method allows you to utilize the power of EnumSet for various scenarios, making it a versatile tool for managing collections of enum constants.