Question

java
Write an application that input a number from the user and checks if all digits are prime numbers using method prime. The number entered can be of any size. If all digits are prime your program should stop. Use do/while for reading the input and any loop format to test if the number is prime. When checking the prime numbers don’t use an if to check numbers from 1 – 9; you need to find an algorithm to check if the number is prime or not. Your method should return an array of numbers that were not prime. Your method should print all the numbers that are not prime and should return false if a non prime number is found. boolean prime (int x);
Enter a 3-digit number: 124
4 is not a prime number!
Enter a 3-digit number: 642
6 is not a prime number!
4 is not a prime number!
Enter a 3-digit number: 352
All Prime! Thank You!

Answer 1

import java.util.*;

public class Main
{
//variable declaration
public static int primeArraySize = 0;
public static int intSize = 0;
  
//function to check prime or not
public static boolean prime(int num)
{
//variable declaration and initialization
boolean flag = false;
switch(num)
{
case 2:
case 3:
case 5:
case 7:
flag = true;
break;
  
}
return flag;
}
  
//method to check number is full prime or not
public static int[] checkFullPrime(int num)
{
boolean prime = true;
int notPrime[] = new int[10];
int i=0, rem;
  
while (num!=0)
{
intSize++;
rem = num % 10;
if(!prime(rem))
{
notPrime[i] = rem;
i++;
primeArraySize++;
}
num = num / 10;
}
notPrime[i] = '\n';
return notPrime;
}

   public static void main(String[] args)
   {
   do
   {
   //variable initialization
   primeArraySize = 0;
intSize = 0;
   int num = 0;
   int notPrime[] = new int[10];
   Scanner input = new Scanner(System.in);
       System.out.print("Enter a 3-digit number: ");
       num = input.nextInt();
      
       notPrime = checkFullPrime(num);
       if(primeArraySize==0)
       {
           System.out.println("All Prime! Thank You!");
           return;
       }
       else
       {
       for(int i=0; i<primeArraySize; i++)
       {
       System.out.println(notPrime[i] + " is not a prime number!");
       }
  
   }
   }while(true);
   }
}

OUTPUT: