// File: MacTest.java

// The SeniorCitizenMacDonald class depends on the Animal interface and shows 
// polymorphism. MacTest is a simple test class for S.C.Mac.
/**
 * A class to sing a popular song.
 */
class SeniorCitizenMacDonald {
    // S.C.Mac doesn't care about type - all animals are treated as interface 
    // type Animal.  So new classes may be added to the system with no 
    // modification of S.C.Mac at all...

    private String sound;	// what an Animal says
    private Animal[] animals;	// array of interface type Animal

    /**
     * Create an S.C.Mac object.
     *
     * @param myAnimals array of Animal references, any of which may point to
     * any class that implements Animal
     */
    public SeniorCitizenMacDonald(Animal[] myAnimals) {
        animals = myAnimals;
    }

    /**
     * Prints lyrics to a popular song, using polymorphic method calls.
     */
    public void sing() {
        // for each Animal in the array...
        for (int ei = 0; ei < animals.length; ei++) {
            sound = animals[ei].getSound();	// polymorphism
            eieio();
            System.out.println("And on this farm he had some "
                    + animals[ei].getPlural() // polymorphism
                    + ",\nE-I-E-I-O.");
            System.out.println("With a(n) " + sound + "-" + sound + " here,\n"
                    + "and a(n) " + sound + "-" + sound + " there,\n"
                    + "here a(n) " + sound + ", there a(n) " + sound
                    + ",\neverywhere a(n) " + sound + "-" + sound + ",");
            eieio();
            System.out.println();
        }
    }

    /**
     * Utility method prints a line of the song. Saves code duplication.
     */
    private void eieio() {
        System.out.println("Senior Citizen MacDonald had a farm,\n"
                + "E-I-E-I-O.");
    }
}

public class MacTest {

    public static void main(String[] args) {
        Animal[] critters = {new Cow(), new Pig(), new Snake()};

        SeniorCitizenMacDonald mac = new SeniorCitizenMacDonald(critters);

        mac.sing();
    }
}

/*  program output  :-)

Senior Citizen MacDonald had a farm,
E-I-E-I-O.
And on this farm he had some cows,
E-I-E-I-O.
With a(n) moo-moo here,
and a(n) moo-moo there,
here a(n) moo, there a(n) moo,
everywhere a(n) moo-moo,
Senior Citizen MacDonald had a farm,
E-I-E-I-O.

Senior Citizen MacDonald had a farm,
E-I-E-I-O.
And on this farm he had some pigs,
E-I-E-I-O.
With a(n) oink-oink here,
and a(n) oink-oink there,
here a(n) oink, there a(n) oink,
everywhere a(n) oink-oink,
Senior Citizen MacDonald had a farm,
E-I-E-I-O.

Senior Citizen MacDonald had a farm,
E-I-E-I-O.
And on this farm he had some giraffes,
E-I-E-I-O.
With a(n) [silence]-[silence] here,
and a(n) [silence]-[silence] there,
here a(n) [silence], there a(n) [silence],
everywhere a(n) [silence]-[silence],
Senior Citizen MacDonald had a farm,
E-I-E-I-O.

*/