Java Program - Find All Prime Numbers in a Range

Mathematics for Programming Numbers (Article) Numbers (Program)

This Java program finds and prints all prime numbers within a specified range, from 10 to 50. The main method iterates through each number in the range and checks if it's prime using the isPrime method. The isPrime method returns true if the number is greater than 1 and has no divisors other than 1 and itself. If a number is prime, it's printed to the console. This process efficiently determines and displays prime numbers in the given range.

Given Input:

start = 10, end = 50;

Expected Output:

11
13
17
19
23
29
31
37
41
43
47

Program:

public class PrimeNumbersInRange {
    public static void main(String[] args) {
        int start = 10, end = 50;

        for (int i = start; i <= end; i++) {
            if (isPrime(i))
                System.out.println(i);
        }
    }

    public static boolean isPrime(int number) {
        if (number <= 1)
            return false;
        for (int i = 2; i <= number / 2; i++) {
            if (number % i == 0)
                return false;
        }
        return true;
    }
}

Output:

11
13
17
19
23
29
31
37
41
43
47

Explanation:

import java.util.Scanner;

public class PrimeNumbersInRange {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the start of the range: ");
        int start = scanner.nextInt();

        System.out.print("Enter the end of the range: ");
        int end = scanner.nextInt();

        System.out.println("Prime numbers between " + start + " and " + end + " are:");

        for (int i = start; i <= end; i++) {
            if (isPrime(i))
                System.out.println(i);
        }
    }

    public static boolean isPrime(int number) {
        if (number <= 1)
            return false;
        for (int i = 2; i <= number / 2; i++) {
            if (number % i == 0)
                return false;
        }
        return true;
    }
}