How to Write a Java Program to Sum the Middle Integers

Creating a Java program to store 10 three-digit integers and calculate the sum of the middle integers can be an excellent exercise for understanding arrays and input-validation logic. This guide will walk you through the process of creating such a program.

Step-by-Step Guide

To write a Java program that stores 10 three-digit integers and calculates the sum of the middle integers, follow the steps outlined below:

Store the integers

The first step is to use an array to hold the 10 integers. An array in Java is a collection of variables of the same type, allowing you to store and manage multiple values in a single variable.

Identify the middle integers

For 10 integers, the middle integers are the 4th, 5th, 6th, and 7th integers. In Java, array indices start at 0, so the middle integers correspond to indices 3, 4, 5, and 6.

Calculate the sum

After storing the integers and identifying the middle ones, the program needs to add these middle integers to find the sum.

Complete Java Program

Below is the complete Java program that implements this logic:

import ;

public class MiddleIntegerSum {
    public static void main(String[] args) {
        Scanner scanner  new Scanner();
        int[] numbers  new int[10];
        int sum  0;
        // Input 10 three-digit integers
        for (int i  0; i  10; i  ) {
            numbers[i]  ();
            // Optional: Validate if the number is a three-digit integer
            while (numbers[i]  100 || numbers[i]  999) {
                ("Invalid input. Please enter a three-digit integer: ");
                numbers[i]  ();
            }
        }
        // Calculate the sum of the middle integers 4th, 5th, 6th and 7th
        sum  numbers[3]   numbers[4]   numbers[5]   numbers[6];
        // Output the result
        ("The sum of the middle integers is: "   sum);
    }
}

Explanation of the Program

The program follows these key steps:

Import Statements: The program imports to read input from the user. Array Declaration: An integer array numbers of size 10 is created to store the integers. Input Loop: A loop runs 10 times to read integers from the user. It checks if the entered integer is a three-digit number and prompts the user again if it is not. Sum Calculation: The program calculates the sum of the integers at indices 3, 4, 5, and 6, which correspond to the 4th to 7th integers. Output: Finally, it prints the sum of the middle integers.

How to Run the Program

To execute the program, follow these steps:

Copy the code into a file named Compile the program using the command javac Run the program using the command java MiddleIntegerSum. Follow the prompts to enter 10 three-digit integers. The program will then display the sum of the middle integers.

Conclusion

Understanding how to write a Java program to store and process 10 three-digit integers is an excellent practice for beginner and intermediate Java developers. By following this guide, you can develop a robust understanding of arrays, loops, and basic input validation in Java.