1. Introduction

In this post, we will write a Java program to generate all prime numbers up to a given number n. A prime number is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers other than itself and 1.

2. Program Steps

1. Declare a class named PrimeGenerator.

2. Inside this class, define the main method.

3. Inside the main method, define a variable n to which up to we have to find the prime numbers.

4. Create a loop to iterate through all numbers from 2 to n.

5. For each number, check whether it is prime or not.

6. If it is prime, print the number.

3. Code Program

public class PrimeGenerator { // Step 1: Declare a class named PrimeGenerator

    // Method to check whether a number is prime or not
    static boolean isPrime(int num) {
        if (num <= 1) return false;
        for (int i = 2; i <= Math.sqrt(num); i++) {
            if (num % i == 0) return false;
        }
        return true;
    }

    public static void main(String[] args) { // Step 2: Define the main method

        int n = 50; // Step 3: Define a variable n

        // Step 4: Create a loop to iterate through all numbers from 2 to n
        for (int i = 2; i <= n; i++) {

            // Step 5: For each number, check whether it is prime or not
            if (isPrime(i)) {

                // Step 6: If it is prime, print the number
                System.out.print(i + " ");
            }
        }
    }
}

Output:

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47

4. Step By Step Explanation

– Step 1: A class named PrimeGenerator is declared.

– Step 2: The main method is defined inside the PrimeGenerator class.

– Step 3: We define a variable n and assign it a value of 50.

– Step 4: A for loop is used to iterate through all numbers from 2 to n.

– Step 5: For each number in the loop, we check whether it is prime or not using the isPrime method.

– Step 6: If the number is prime, it gets printed to the console.

– The isPrime method checks whether a number is prime by ensuring it is not divisible by any number from 2 to the square root of the number itself.