Lab 10-31 (1) product of N positive numbers

product of N positive numbers
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
public class lab1031 {
public lab1031() {
}

public static void main(String[] args)throws IOException {
BufferedReader keyboard =new BufferedReader(new InputStreamReader(System.in));
System.out.println("Please enter the negtive numbers");
System.out.println("Enter a positive number to exit");

int product=1;
String nextString = keyboard.readLine();
int next = Integer.parseInt(nextString.trim());
while(next>=0)
{
product=product*next;
nextString = keyboard.readLine();
next = Integer.parseInt(nextString.trim());
}
System.out.println("product is "+product);
}
}