Sets

The Set interface provides a way to store unique elements. This tutorial will teach you how to use sets in Java.

Creating a Set

To create a set, use the HashSet class:

import java.util.HashSet;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        Set names = new HashSet<>();
        names.add("Alice");
        names.add("Bob");
        names.add("Charlie");
        
        System.out.println(names);
    }
}
      

Checking for Elements in a Set

Use the contains method to check if an element exists in a set:

public class Main {
    public static void main(String[] args) {
        Set names = new HashSet<>();
        names.add("Alice");
        names.add("Bob");
        names.add("Charlie");
        
        System.out.println(names.contains("Bob")); // Outputs: true
    }
}
      

Removing Elements from a Set

Use the remove method to remove elements from a set:

public class Main {
    public static void main(String[] args) {
        Set names = new HashSet<>();
        names.add("Alice");
        names.add("Bob");
        names.add("Charlie");
        
        names.remove("Bob");
        System.out.println(names); // Outputs: [Alice, Charlie]
    }
}
      

Iterating Over a Set

You can iterate over a set using a for-each loop:

public class Main {
    public static void main(String[] args) {
        Set names = new HashSet<>();
        names.add("Alice");
        names.add("Bob");
        names.add("Charlie");
        
        for (String name : names) {
            System.out.println(name);
        }
    }
}
      

Continue exploring our intermediate tutorials to learn more about Java programming.