Java LinkedHashSet

Java LinkedHashSet

A LinkedHashSet is a collection that stores unique elements and remembers the order they were added.

It is part of the java.util package and implements the Set interface.

Create a LinkedHashSet

import java.util.LinkedHashSet; // Import the LinkedHashSet class

LinkedHashSet<String> cars = new LinkedHashSet<>();

Now you can use methods like add(), contains(), and remove() to manage your collection.

Add Elements

To add elements to a LinkedHashSet, use the add() method:

import java.util.LinkedHashSet;

public class Main {
  public static void main(String[] args) {
    LinkedHashSet<String> cars = new LinkedHashSet<>();
    cars.add("Volvo");
    cars.add("BMW");
    cars.add("Ford");
    cars.add("BMW");  // Duplicate
    cars.add("Mazda");

    System.out.println(cars);
  }
}

Check if an Element Exists

Use contains() to check for an element:

cars.contains("Mazda");

Remove an Element

Use remove() to remove an element:

cars.remove("Volvo");

Remove All Elements

Use clear() to remove all elements:

cars.clear();

LinkedHashSet Size

Use size() to count how many unique elements are in the set:

cars.size();

Note: Duplicate values are not counted - only unique elements are included in the size.

Loop Through a LinkedHashSet

Loop through the elements of a LinkedHashSet with a for-each loop:

LinkedHashSet<String> cars = new LinkedHashSet<>();
// Add elements...

for (String car : cars) {
  System.out.println(car);
}

HashSet vs LinkedHashSet