Question

A prime number is a number that is only evenly divisible by itself and 1. For example, the number 5 is prime because it can only be evenly divided by 1 and 5. The number 6, however, is not prime because it can be divided evenly by 1, 2, 3, and 6.

Design a Boolean function called isPrime, that accepts an integer as an argument and returns True if the argument is a prime number, or False otherwise. Use the function in a program that prompts the user to enter a number and then displays a message indicating whether the number is prime. The following modules should be written:

getNumber, that accepts a Ref to an integer, prompts the user to enter a number, and accepts that input

isPrime, that accepts an integer as an argument and returns True if the argument is a prime number, or False otherwise

showPrime, that accepts an integer as an argument , calls isPrime, and displays a message indicating whether the number is prime

The main module, that will call getNumber and showPrime

Answer 1

Solution:

Program implementation:

import java.util.*; // import statement for Scanner class.
public class prime{
// getNumber prompts for input.
static int getNumber(int n){
System.out.print("Enter a number: ");
Scanner sc=new Scanner(System.in);//creates an object of scanner class.
n=sc.nextInt(); // takes input.
System.out.println(n); // prints input.
return n; // returns the n value.
}
// isPrime() function checks whether n value is prime or not.
static boolean isPrime(int n){
if(n==0 || n==1){
return false; // if n ivalue is 0 or 1 returns false.
}
for(int i=2;i<=n/2;i++){
if(n%i==0) // if n has more than 2 factors returns false.
return false;
}
return true; // if n has only two factors.
}
static void showPrime(int n){
if(isPrime(n)){ // if isPrime() returns true.
System.out.println(n+" is a prime number.");
}
else{ // if isPrime() returns false.
System.out.println(n+" is not a prime number.");
}
}
public static void main(String []args){
int n=0; // variable to take input.
n=getNumber(n); // function call to getNumber().
showPrime(n); // function call to showPrime().
}
}

Program screenshot:

Program input and output screenshot: