I made this today to pass the time. Source copied below for convenience, old technique redacted for space.
package primeNumbers;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
* @author drewry pope
*/
public class Main {
//New method, divide iO against every found prime up to iO
public static void main(String[] args)
{
List<Integer> primeNumbers= new ArrayList<Integer>(); //initialize new ArrayList to store primes
for (int iO = 2; iO <= 100; iO++) { //For numbers 2 to 100
for (int iI = 0; iI <= primeNumbers.size(); iI++) { //For primeNumbers index 0 to end of List
if (iI == primeNumbers.size()) { //if on last iteration,
primeNumbers.add(iO); //then add iO as prime
}else if (0 != iO % primeNumbers.get(iI)) { //if iO is not divisible by primeNumber(iI)
continue; //then continue from beginning of inner for loop
}
break; //exit inner For loop if number divides by primeNumber(iI) or number was added as prime
}
}
Iterator<Integer> itr = primeNumbers.iterator(); //initialize an iterator to output array
System.out.print(itr.next()); //print first prime without a comma
while(itr.hasNext()) { //while there's still more integers to iterate
System.out.print(", " + itr.next()); //print next number with minor formatting
}
}
}