Question

A duplicate element is added to a set. Then which of the following about add 0 is true? a. The add 0 generates compilation erron b. The add0 throws runtime exception c. The add0 rejects duplicate element d. The add0 returns false when duplicate is added

Short answer

The add0 method returns false when a duplicate element is added.

Step-by-step solution

Understand the definition of a Set

A Set is a data structure that stores unique elements, meaning that it cannot contain duplicate values.

Evaluate the behavior when adding a duplicate element

When trying to add a duplicate element to a Set, the Set will not add the element again. Instead, it will typically return a signal indicating the element was already present.

Consider the options about the add0 method

Review the given options: (a) compilation error, (b) runtime exception, (c) reject the element, and (d) return false. The appropriate behavior when adding a duplicate element to a Set in most programming languages is that the method will return false, indicating the operation was not successful because the element was already in the Set.

Identify the correct answer

Based on the behavior of Set operations in handling duplicate elements, the correct answer is: The add0 method returns false when a duplicate element is added.

Key concepts

Duplicate Elements in Set

In Java, the Set data structure is part of the Java Collections Framework. A Set is designed to store unique elements, which means it does not allow duplicate values. When you try to add a duplicate element to a Set, the existing rules of the Set prevent that element from being added again.
This property is crucial for certain applications where you need to ensure that each entry is unique.
If an attempt is made to add a duplicate element, the Set remains unchanged. This is because the Set checks if the element is already present before any addition.
In essence, the Set maintains its unique collection by rejecting duplicates silently.

Set Operations

Set operations are quite straightforward yet powerful. They allow you to perform various actions while ensuring all elements remain unique.
Here are some standard operations you can perform with Sets in Java:

• **Add elements** - Using the `add` method, you can add elements to the Set. If the element is not already present in the Set, it will be added.
  
  
• **Remove elements** - The `remove` method allows you to remove elements from the Set.
  
  
• **Check if an element exists** - By using the `contains` method, you can check if an element is already in the Set.
  
  
• **Get the size of the Set** - The `size` method returns the number of elements in the Set.

These operations help manage the collection of elements efficiently. Since Sets do not allow duplicates, they are highly useful in scenarios where uniqueness is required, like managing IDs or any other unique key values.

Return Values of add Method

The `add` method in a Set is used to add elements. This method carries additional functionality compared to simply placing elements into a collection.

When using the `add` method to insert an element in a Set, it returns a boolean value:

• **True** - If the element was not already in the Set and was successfully added. This indicates that the insertion was successful.
  
  
• **False** - If the element already exists in the Set. This indicates that the Set does not permit duplicate elements, and hence, the insertion was rejected.

By returning a boolean value, the `add` method provides immediate feedback about the operation's success. This is particularly useful for situations where you need to ensure an element is unique before performing further actions, as you can handle the failure case directly and appropriately.