VMoza VMoza - 1 month ago 12
Java Question

Java Prime Number Method

The question is exactly as follows:

Write a method that determines whether a number is prime.
Then use this method to write an application that determines and displays all the prime numbers less than 10,000.

I have already written a program that finds all prime numbers up to 10,000, but then found a simpler and more efficient one on StackOverflow, and that is this:

package prime;

import java.util.Scanner;

public class Prime
{
public static void main(String[] args)
{
for(int i = 1; i <= 10000; i++)
{
int factors = 0;
int j = 1;

while(j <= i)
{
if(i % j == 0)
{
factors++;
}
j++;
}
if (factors == 2)
{
System.out.println(i);
}
}
}
}


Since I am very new to Java and am especially not good at methods, this problem is especially difficult for me. I tried making a method, but nothing is being returned, and when I try to return something I get error after error after error.

The help I need is mainly just Pseudo-Code for what I should do to tackle this problem; I'm not asking you for the answer, I'm just asking for a start.

Answer Source
package prime;

public class Prime 
{
    public static void main(String[] args) 
    {
       for(int i = 1; i <= 10000; i++)
       {
         if (isPrimeNumber(i))
         {
            System.out.println(i);
         }
       }
    }


    public static boolean isPrimeNumber(int i) {
        int factors = 0;
        int j = 1;

        while(j <= i)
        {
            if(i % j == 0)
            {
                factors++;
            }
            j++;
        }
        return (factors == 2);
  }
}