Java LinkedHashSet contains()

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In this guide, you will learn about the LinkedHashSet contains() method in Java programming and how to use it with an example.

1. LinkedHashSet contains() Method Overview

Definition:

The contains() method of the LinkedHashSet class in Java is used to check whether a specific element is present in the set or not. It returns true if the set contains the specified element, otherwise, it returns false.

Syntax:

public boolean contains(Object o)

Parameters:

- o: The element whose presence in this set is to be tested.

Key Points:

- The contains() method is used to check the presence of a single element in the LinkedHashSet.

- The method will return true if the specified element is found in the set; otherwise, it will return false.

- The method accepts any Object as its parameter.

- The contains() method works in constant time, O(1), for this implementation, making it efficient.

- If the object passed to contains() is not of the correct type or is null, the method will return false.

2. LinkedHashSet contains() Method Example

import java.util.LinkedHashSet;

public class LinkedHashSetContainsExample {

    public static void main(String[] args) {
        LinkedHashSet<String> fruitSet = new LinkedHashSet<>();

        // Adding elements to the LinkedHashSet
        fruitSet.add("Apple");
        fruitSet.add("Banana");
        fruitSet.add("Cherry");

        // Printing the LinkedHashSet
        System.out.println("LinkedHashSet: " + fruitSet);

        // Checking the presence of elements
        System.out.println("Contains Apple? " + fruitSet.contains("Apple"));
        System.out.println("Contains Orange? " + fruitSet.contains("Orange"));
        System.out.println("Contains null? " + fruitSet.contains(null));
    }
}

Output:

LinkedHashSet: [Apple, Banana, Cherry]
Contains Apple? true
Contains Orange? false
Contains null? false

Explanation:

In this example, we have a LinkedHashSet containing some elements. 

We then use the contains() method to check the presence of various elements in the set, including a null value. The output demonstrates that the method accurately identifies whether the specified elements are present in the LinkedHashSet or not, returning true or false accordingly.