Java Collections HashSet

In Java, a `HashSet` is a collection that stores unique elements. It is part of the Java Collections Framework and provides a fast and efficient way of storing and retrieving data. Here are some basics of the `HashSet` in Java:

1. Creating a `HashSet`: To create a `HashSet`, you can use the `HashSet` class and specify the type of objects you want to store in the set. For example:

HashSet names = new HashSet();

Here, a `HashSet` of strings is created.

2. Adding elements: You can add elements to a `HashSet` using the `add` method. For example:

names.add("Alice");
names.add("Bob");
names.add("Charlie");

Here, three elements are added to the `HashSet`.

3. Removing elements: You can remove elements from a `HashSet` using the `remove` method. For example:

names.remove("Bob");

Here, the element “Bob” is removed from the `HashSet`.

4. Checking for element existence: You can check if an element exists in a `HashSet` using the `contains` method. For example:

boolean containsAlice = names.contains("Alice");

Here, the variable `containsAlice` is set to `true` if “Alice” exists in the `HashSet`.

5. Iterating over elements: You can iterate over the elements in a `HashSet` using a for-each loop. For example:

for (String name : names) {
    System.out.println(name);
}

Here, each element in the `HashSet` is printed to the console.

6. Hashing: The `HashSet` uses a hashing algorithm to store and retrieve elements. This provides fast access to elements and ensures unique elements in the set.

The `HashSet` in Java is a powerful data structure that allows you to store and manipulate collections of unique objects in a fast and efficient way. By understanding the basics of the `HashSet`, you can write more efficient and effective code that can handle complex data structures.