/**
 * PrimeGenerator represents the sequence of prime numbers
 * less than a specified number.
 *
 */
public class PrimeGenerator
{
    private int limit;
    private int currentPrime;

    /**
     * Creates a PrimeGenerator which can get primes up to the limit
     * @param limit the number that all the primes must be less than
     */
    public PrimeGenerator(int limit)
    {
        this.limit = limit;
        currentPrime = 2; //the first prime number
    }

    public boolean isPrime(int n)
    {

        if (n==1)
        {
            return false;
        }

        if ( n ==2 )
        {
            return true;
        }

        if (n % 2 == 0)
        {
            return false;
        }

        for(int i = 3; i < n; i= i+2)
        {
            if (n%i == 0)
            {
                return false;
            }
        }

        return true;
    }

    public int nextPrime() {
        int number = -1;
        for(int i=currentPrime+1; i<limit; i++) {
            if(isPrime(i) == true) {
                number = i;
                return number;
            }
        }
        return number;
    }

    public void setLimit(int newLimit)
    {
        limit = newLimit;
    }
}