Chapter 18: Problem 25

What does the Hashset class's add method do when you try to add a duplicate item?

Short Answer

Expert verified

Answer: When the add() method is called with an element that is already present in the HashSet, it does not add the duplicate element again. Instead, it returns false, indicating that the element is already present and no changes have been made to the set.

Step by step solution

Understanding HashSet class

A HashSet is a collection class in Java that implements the Set interface. It stores unique elements and doesn't allow duplicate values. The elements in a HashSet are unordered, and it uses the hashCode() method to improve the performance of the add, remove, and contains operations.

Behavior of add method when adding duplicates

When the add() method is called with an element that is already present in the HashSet, it does not add the duplicate element to the set again. Instead, it returns false, indicating that the element is already present and no changes have been made to the set. Here's an example to demonstrate the behavior of the add() method when adding duplicate items: ```java import java.util.HashSet; public class HashSetExample { public static void main(String[] args) { // Create a HashSet HashSet set = new HashSet(); // Add elements to the set set.add("Apple"); set.add("Banana"); // Attempt to add a duplicate element boolean isAdded = set.add("Apple"); // Print the result System.out.println("Set: " + set); System.out.println("Is duplicate added? " + isAdded); } } ``` Output: ``` Set: [Apple, Banana] Is duplicate added? false ``` In the above example, we attempted to add "Apple" twice to the HashSet. The second call to `set.add("Apple")` returns false since "Apple" is already present in the set, and the set remains unchanged.

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What does the Hashset class's add method do when you try to add a duplicate item?

Short Answer

Step by step solution

Understanding HashSet class

Behavior of add method when adding duplicates

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