public class GenericExample {

    // generic method given a type T
    // returns the last element from an array of Ts
    // note the <T> is to denote generic method
    // the T after that is the return type
    public static <T> T getLast(T list[]) {
        if (list == null || list.length == 0) {
            return null;
        }

        // doesn't make sense even if we sometimes have array of cats
        //list[0].miaow();

        return list[list.length - 1];
    }

    // generic method given a type T
    // returns whether list has nulls in it
    public static <T> boolean hasNulls(T list[]) {
        // if no list or no length, no nulls
        if (list == null || list.length == 0) {
            return false;
        }
        for (int i = 0; i < list.length; i++) {
            if (list[i] == null) {
                return true;
            }
        }
        return false;
    }

    // generic method with bounded type
    // note we would use "extends" even for interfaces
    // a and b must be the same type
    // which must be or extend Namey
    public static <T extends Namey> T matchesName(String s, T a, T b) {
        // if a's name matches
        if (a.getName().equals(s) ) {
            return a;
        }
        // if b's name matches
        if (b.getName().equals(s) ) {
            return a;
        }
        // neither matches
        return null;
    }
    
    public static void main(String[] args) {

        // this pair holds a string and an int
        // we can't really say int, so we Integer wrapper class
        // Java will autobox the ints we use for us
        MyPair<String, Integer> p1 =
                new MyPair<String, Integer>("hello", 53);
        System.out.println(p1);

        // Java unboxes too -- Integer becomes int
        int q = p1.getSecond();

        // this pair holds an int and a Cat
        MyPair<Integer, Bee> p2 =
                new MyPair<Integer, Bee>(75, new Bee());
        System.out.println(p2);

        // we specified the type, 
        // so we know what getSecond returns for this pair
        // so no problem calling Cat-specific method.
        p2.getSecond().sting();


        Coordinate c1 = new Coordinate(2, 4);
        Coordinate c2 = new Coordinate();
        System.out.println(c1 + " to " + c2 + " is "
                + c1.distance(c2));


        // array of ninjas
        Ninja[] nlist = {new Ninja("Mr. Death"), new Ninja("Black Widow"),
            new Ninja("Killy")};

        // to use with generic method, use Integer wrapper class
        // and let Java autobox
        Integer[] intlist = {1, 2, 3, 4, 5};

        // call generic method for ninjas
        System.out.println(getLast(nlist));
        // we know it will return a ninja
        getLast(nlist).assassinate(p2.getSecond());

        // call generic method for ints
        System.out.println(getLast(intlist));


        Ninja n1 = new Ninja("Ninja A");
        Ninja n2 = new Ninja("Ninja B");
        // we know it will return a Ninja
        Ninja nMatch = matchesName("Ninja A", n1, n2);

        MyPair <Bee, Boolean> pa= new MyPair(new Bee(), true);
        MyPair <Bee, Boolean> pb = new MyPair(new Bee(), false);
        pa.setName("Deadly Bees");
        pb.setName("Covered in Bees");
        // we know it will return a MyPair<Bee, Boolean> whose first is a Bee
        matchesName("Covered in Bees", pa, pb).getFirst().sting();

    }
}