Question

(Duplicate Elimination) Use a one-dimensional array to solve the following problem: Write an application that inputs five numbers, each between 10 and 100 , inclusive. As cach number is read, display it only if it is not a duplicate of a number already read. Provide for the "worst case," in which all five numbers are different. Use the smallest possible array to solve this problem. Display the complete set of unique values input after the user enters each new value.

Short answer

Use an array of size 5 and add numbers to it if they are not duplicates.

Step-by-step solution

Initialize Array and Variables

Start by initializing a one-dimensional array with a size of 5 to store unique numbers. Also, create a counter variable to keep track of how many unique numbers are currently stored in the array.

Input Numbers

Prompt the user to input a number between 10 and 100. Repeat this step for a total of five inputs from the user.

Check for Duplicates

For each number entered, check if it is already present in the array. If not, add the number to the array at the index indicated by the counter, then increment the counter. If the number is a duplicate, do not add it to the array and display a message indicating it's a duplicate.

Display Unique Numbers

After each number input by the user, display all the unique numbers stored in the array so far. This shows the user the current set of non-duplicated numbers.

Key concepts

Duplicate Elimination

In Java, the process of duplicate elimination within an array is integral to managing data efficiently. Imagine you're tasked with collecting user input and ensuring each entry is unique. This is where duplicate elimination becomes useful. By regularly checking for repeated values, we only retain the unique numbers, discarding any repeats.

For example, when a user inputs a number, our application checks if this number already exists in the array of saved numbers. If it doesn't exist, we add it. This ensures that every number in our list remains unique. This step is critically important in situations where data integrity relies on maintaining distinct items, such as usernames in a database or product IDs in inventory systems.

User Input Validation

User input validation is crucial when you're asking for user input in Java applications. We need to make sure the inputs fall within the desired range to prevent incorrect or damaging data from entering the system.

In our task, we specify that numbers should be between 10 and 100. This means when the user inputs a number, we must verify it falls within these parameters. If a user tries to enter a number outside this range, it should be rejected, possibly with a message prompting the user to try again. The validation process helps to maintain the integrity and functionality of the application, safeguarding against errors and undesirable outcomes.

Array Initialization

Array initialization is a foundational concept in Java, particularly when it comes to working with collections of data. Before you can use an array to store values, you must declare and initialize it.

In our example, we initialize a one-dimensional array with a size of 5, which means it can store up to five numbers. This size is chosen to closely match the number of inputs expected in the exercise, keeping the implementation simple and efficient. Initializing an array properly means allocating enough space while avoiding wastage, adhering to the principle of optimal resource use.

Conditional Statements

Conditional statements, such as if-else constructs, are a programming staple. They allow your Java application to make decisions based on conditions you define. This is particularly useful for executing specific actions when certain conditions are met.

In our example, conditional statements help check if a number is duplicated or if it falls outside a specified range. When a user inputs a number, an if statement can determine if the number is already in the array or if it's within the acceptable range of 10 to 100. Based on this check, the program can either accept the input or prompt the user to enter something different. By using conditional statements effectively, we build programs that are both robust and responsive.