Program to Find Prime Numbers in a Given Range in Java

Finding Prime Numbers in a Range

A prime number is a natural number greater than 1 that has no divisors other than 1 and itself.

We will explore different methods to find all prime numbers within a given range using Java programming.

Method 1: Using a for Loop

We iterate through the given range and check if each number is prime.

import java.util.Scanner;

public class Main {
    public static boolean isPrime(int num) {
        if (num < 2) return false;
        for (int i = 2; i * i <= num; i++) {
            if (num % i == 0)
                return false;
        }
        return true;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter the range (start end): ");
        int start = scanner.nextInt();
        int end = scanner.nextInt();
        scanner.close();
        
        System.out.print("Prime numbers between " + start + " and " + end + " are: ");
        for (int i = start; i <= end; i++) {
            if (isPrime(i)) {
                System.out.print(i + " ");
            }
        }
    }
}
            

Output:

Enter the range (start end): 10 20
Prime numbers between 10 and 20 are: 11 13 17 19