Question

\((\text { Duplicate Elimination })\) Write a program that reads in a series of first names and eliminates duplicates by storing them in a Set. Allow the user to search for a first name.

Short answer

Initialize a Set to store names, read user input to add names to the Set, check if a user-provided name for search is in the Set, and loop the process allowing the user to add more names or exit.

Step-by-step solution

- Create a Set to Store Names

Initialize an empty Set in your program to store the first names. This will inherently eliminate duplicates since Sets do not allow duplicate values.

- Read and Store First Names

Create a loop that allows the user to enter first names. Each time a name is entered, add it to the Set. If the name is already in the Set, it will not be added again, thus eliminating duplicates.

- Implement Search Functionality

Prompt the user to enter a first name they wish to search for. Check if this name exists in the Set. If it does, inform the user that the name was found; if not, tell the user that the name is not present.

- Continue or Exit the Program

After searching for a name, ask the user if they would like to continue by adding more names or exit the program. The program should only end when the user decides to exit.

Key concepts

Duplicate Elimination in Java

When working with collections of data in Java, one commonly faced issue is the presence of duplicate elements. Fortunately, Java provides a built-in mechanism to handle such occurrences through the use of Set collections. A Set is a type of collection that does not allow duplicate elements, making it an ideal choice for duplicate elimination.

In the context of the provided exercise, when a user inputs a series of first names, implementing a Set ensures that if a name has already been entered, it won't be added again. This feature is intrinsic to the Set and requires no additional logic to check for duplicates – the Set simply ignores any attempt to add an already existing item.

Benefits of Using a Set

• Simplicity: It requires less code and is automatically managed by the Java Collections Framework.
• Performance: Since Sets are designed to handle uniqueness, they often perform faster checks for duplicates compared to a list or an array.
• Clarity: The intent of having unique elements is clearly communicated by the choice of data structure.

It's important for students to remember that while Sets are powerful, the order of elements in most types of Sets is not guaranteed, which can be an important aspect depending on the use case.

Search Functionality in Java

Searching for elements within a collection is a fundamental operation in Java programming. The ability to quickly and efficiently find an item holds significant importance, especially when dealing with large sets of data. Within the Java Collection Framework, each collection type provides methods to ascertain if a particular element exists.

In the solution for the exercise, the search functionality is realized through the method contains provided by the Set interface. When the user wishes to search for a first name, you invoke this method and it returns a boolean indicating whether the Set contains the specified element.

Searching in a Set

Due to the unique nature of Sets, searching is usually faster compared to Lists, particularly when searching for the absence of an item, because the check stops as soon as a unique element is found or not found. Taking advantage of these built-in methods allows for concise and readable code, highlighting the robustness of Java's standard libraries.

Java User Input

Interactivity in Java programs often requires capturing input from the user, which can be done by using various methods and classes provided in Java. The most common way is through the Scanner class, which can parse primitive types and strings using regular expressions.

In our exercise scenario, the Scanner class is used to read first names from the console. The steps for using this class are straightforward:

• Create an instance of Scanner by passing System.in (standard input stream) to its constructor.
• Use methods such as nextLine() to capture the user input as String values.
• Process the input according to the program's needs—in this case, adding the input to a Set or searching within it.

It's critical to understand the flow of user input in Java programs and the handling of potential exceptions that may arise, such as InputMismatchException. By thoroughly understanding user input handling, students can better manage user interactions in Java applications, ensuring a smooth user experience and robust software.