How you can do prime number program without modules in java?

Answer 1

package javaapplication1;

public class JavaApplication1 {

public static boolean is_prime(int val){
if (val<0) val*=-1;
if (val<2) return false;
if (val%2==0) return val==2;
int max = (int)Math.sqrt(val)+1;
for (int div=3; divif (val%div==0)
return false;
return true;
}

public static int next_prime(int val) {
do {
++val;
} while (!(is_prime(val)));
return val;
}

public static int prev_prime(int val) {
do {
--val;
} while (!(is_prime(val)));
return val;
}

public static void main(String[] args) {
System.out.print ("List of primes from -50 to 50:\n");
for (int i=-50; i<=50; ++i){
if (is_prime(i)) {
System.out.print (i);
System.out.print (" is prime\n");
}
}

System.out.print ("The next prime after -42 is ");
System.out.println (next_prime(-42));
System.out.print ("The previous prime before -42 is ");
System.out.println (prev_prime(-42));
}
}