Check Given Number Is a Prime Number or Not Java Program

Program:

Write a program to check the given number is a prime number or not?

Description:

A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself. A natural number greater than 1 that is not a prime number is called a composite number. For example, 5 is prime, as only 1 and 5 divide it, whereas 6 is composite, since it has the divisors 2 and 3 in addition to 1 and 6. The fundamental theorem of arithmetic establishes the central role of primes in number theory: any integer greater than 1 can be expressed as a product of primes that is unique up to ordering. This theorem requires excluding 1 as a prime.

Code:

package com.java2novice.algos;

public class MyPrimeNumCheck {

    public boolean isPrimeNumber(int number){
        
        for(int i=2; i<=number/2; i++){
            if(number % i == 0){
                return false;
            }
        }
        return true;
    }
    
    public static void main(String a[]){
        MyPrimeNumCheck mpc = new MyPrimeNumCheck();
        System.out.println("Is 17 prime number? "+mpc.isPrimeNumber(17));
        System.out.println("Is 19 prime number? "+mpc.isPrimeNumber(19));
        System.out.println("Is 15 prime number? "+mpc.isPrimeNumber(15));
    }
}

Output:

Is 17 prime number? true
Is 19 prime number? true
Is 15 prime number? false

• List Of All Java Programs Frequently Asked In Java Interviews