一个简单的JAVA问题

class exercise {
public static void main(String[] args) {
int n = 0;
for (int i=2; i<=100; i++) {
for (int j=2; j<=i/2; j++) {
if (i%j == 0) {
break;
}
}
if (j > i/2) {
n += i;
}
}
}
System.out.print(n);
}

import java.util.*;
public class Primes
{
public static void main(String[] args)
{
int sum = 0;
for (long i = 2; i <= 100; i++)
{
long a = 1;
for (long n = 2; n < i; n++)
{
a = a * ( i % n);
}
if (a != 0)
{
sum += i;
System.out.println(i);
}
}
System.out.println(sum);
}
}