/**
 * Class for rational numbers (fractions).
 * @author B. L. Massingill.
 * @see <a href="../source/RationalNumber.java">Source code</a>
 */
public class RationalNumber {

    /* Instance variables.  Every object gets one of each of these. 
     * (Notice that this is not a documentation comment; people using
     * this class don't need to read it.)
     */
    private int numer;
    private int denom;

    /** 
     * Constructs a rational number with specified numerator, denominator.
     * @param n numerator
     * @param d denominator
     */
    public RationalNumber(int n, int d) {
        numer = n;
        denom = d;
    }

    /**
     * Converts a rational number to printable form.
     * @return printable representation of number ( numerator / denominator).
     */
    public String toString() {
        return Integer.toString(numer) + " / " + Integer.toString(denom);
    }

    /**
     * Compares two rational numbers for equality.  (This is not a very
     *   Java-esque function; the instance method equals() below is usually
     *   preferred.)
     * @param n1 
     * @param n2 
     * @return true if n1 and n2 are equal, false if not
     */
    public static boolean isEqual(RationalNumber n1, RationalNumber n2) {
        /* the long version, perhaps more readable for beginners */
        int temp1 = n1.numer * n2.denom;
        int temp2 = n2.numer * n1.denom;
        if (temp1 == temp2)
            return true;
        else
            return false;
        /* the short version, same result */
        /* return (n1.numer * n2.denom) == (n2.numer * n1.denom); */
    }

    /**
     * Compares two rational numbers for equality.  
     * @param n 
     * @return true if current object and n are equal, false if not
     */
    public boolean equals(RationalNumber n) {
        int temp1 = numer * n.denom;
        int temp2 = n.numer * denom;
        if (temp1 == temp2)
            return true;
        else
            return false;
        /* the short version, same result */
        /* return (numer * n.denom) == (denom * n.numer); */

    }

    /**
     * Multiplies two rational numbers.  (Again, it would probably be more
     *   Java-esque to make this an instance method.)
     * @param n1 
     * @param n2
     * @return n1 times n2
     */
    public static RationalNumber multiply(RationalNumber n1, 
            RationalNumber n2) {

        RationalNumber newNum = 
            new RationalNumber(n1.numer * n2.numer, n1.denom * n2.denom);
        return newNum;

        /* shorter version, same result */
        /*return new RationalNumber(n1.numer * n2.numer, n1.denom * n2.denom);*/
    }

    /**
     * Main method showing example uses of methods.
     * @param args command-line arguments, unused
     */
    public static void main(String[] args) {
        RationalNumber n1 = new RationalNumber(5, 1);
        RationalNumber n2 = new RationalNumber(5, 2);
        System.out.println("n1 = " + n1.toString());
        System.out.println("n2 = " + n2.toString());

        if (isEqual(n1, n1))
            System.out.println("n1, n1 equal");
        else
            System.out.println("n1, n1 not equal");
        if (isEqual(n1, n2))
            System.out.println("n1, n2 equal");
        else
            System.out.println("n1, n2 not equal");

        n2 = new RationalNumber(10, 2);
        System.out.println("n2 = " + n2.toString());
        if (isEqual(n1, n2))
            System.out.println("n1, n2 equal");
        else
            System.out.println("n1, n2 not equal");
        if (n1.equals(n2))
            System.out.println("n1, n2 equal (using equals() function)");
        else
            System.out.println("n1, n2 not equal (using equals() function)");

        RationalNumber n = multiply(n2, n2);
        System.out.println("n2 * n2 = " + n);
    }
}