Java Program to List Prime Numbers from 1 to 100 – Step‑by‑Step Guide

What is a Prime Number?

A prime number is a natural number greater than one that has no positive divisors other than 1 and itself. Examples include 2, 3, 5, 7, 11, 13, 17, and so on.

Important: 0 and 1 are not prime, and 2 is the sole even prime number.

Java Program to Print Prime Numbers Between 1 and 100

Below is a clear, commented Java program that enumerates all prime numbers from 1 to 100:

public class PrimeNumbersDemo {

    public static void main(String[] args) {
        int maxCheck = 100;
        StringBuilder primes = new StringBuilder();

        for (int i = 2; i <= maxCheck; i++) {
            if (isPrime(i)) {
                primes.append(i).append(' ');
            }
        }

        System.out.println("Prime numbers from 1 to " + maxCheck + " are:");
        System.out.println(primes.toString());
    }

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

Expected Output

Prime numbers from 1 to 100 are:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Feel free to modify maxCheck to generate primes up to any limit.

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