Enumset Example in Java

Introduction

EnumSet is a classic Java console program that demonstrates the concept with complete source code and sample output. The Collections Framework provides ArrayList, HashMap, HashSet and related data structures.

This tutorial walks through the program line by line, explains how the logic works, and highlights best practices you can apply in your own code.

Definition

EnumSet inherits AbstractSet and implements Set Interface. EnumSet is the Set implementation for enum types.

Example Program

import java.util.EnumSet;

public class EnumSetExample {

    public static void main(String[] args) {
        // Adding elements to EnumSet
        EnumSet<Directions> directionsEnum1 = EnumSet.allOf(Directions.class);
        EnumSet<Directions> directionsEnum2 = EnumSet.of(Directions.left, Directions.right, Directions.top);
        EnumSet<Directions> directionsEnum3 = EnumSet.complementOf(directionsEnum2);
        EnumSet<Directions> directionsEnum4 = EnumSet.range(Directions.right, Directions.bottom);

        System.out.println("All Elements in Enum class as EnumSet : " + directionsEnum1);
        System.out.println("Adding only certain values in EnumSet : " + directionsEnum2);
        System.out.println("Taking complementOf above EnumSet : " + directionsEnum3);
        System.out.println("Adding a range(from right to bottom) of values from Enum in EnumSet : " + directionsEnum4);
    }

    enum Directions {

        left, right, top, bottom
    }
}

Sample Output

All Elements in Enum class as EnumSet : [left, right, top, bottom]
Adding only certain values in EnumSet : [left, right, top]
Taking complementOf above EnumSet : [bottom]
Adding a range(from right to bottom) of values from Enum in EnumSet : [right, top, bottom]

When to use

Use this enumset example when learning or revising core Java syntax.

How it works

1. Execution begins in the main method — the JVM calls this method when you run the class.

2. import java.util.EnumSet; imports a class used later in the program.

3. EnumSet<Directions> directionsEnum1 = EnumSet.allOf(Directions.class); updates a variable used in the calculation or output.

4. EnumSet<Directions> directionsEnum2 = EnumSet.of(Directions.left, Directions.right, Directions.top); updates a variable used in the calculation or output.

5. EnumSet<Directions> directionsEnum3 = EnumSet.complementOf(directionsEnum2); updates a variable used in the calculation or output.

6. EnumSet<Directions> directionsEnum4 = EnumSet.range(Directions.right, Directions.bottom); updates a variable used in the calculation or output.

7. A println / print call writes text to the console — part of the sample output below.

8. A println / print call writes text to the console — part of the sample output below.

Best Practices

• Use meaningful variable and class names that describe their purpose.
• Compile and run the program locally — modify values to see how output changes.
• Read compiler errors carefully; they usually point to the exact line to fix.

Common Mistakes

• Copying code without understanding each line — practice by changing one statement at a time.
• Mismatching the public class name and the .java filename.
• Forgetting semicolons at the end of statements.