Generics

package merjavabasics;

/**
 * @author Meredith
 * Generics ..wooo.*/
public class MerGenerics<T>{

    static interface Eatable{}
    static interface Drinkable{}
    static class Food{}
    static class MilkShake extends Food implements Eatable,Drinkable{}

    /* This says that MerGenericsJr extends MerGenerics, and it has a
     *  different type param, U, which extends Number and implements
     *  Eatable and Drinkable.
     *  Because MerGenericsJr still extends MerGenerics<T>,
     *  it may also make use of T.*/
    public class MerGenericsJr<U extends Food & Eatable & Drinkable> extends MerGenerics<T>
    {
        @Override
        public T METHOD(T t){
            System.out.println("Returning a "+t.getClass());
                return t;

        }
        /*Defining generic type S on the fly*/
        public <S extends T> T STMETHOD(S s)
        {
            return (T)s;
        }
        /*compiler doesn't complain on this useless generic:
          pointless definition of local generic S never used*/
        public <S extends T> int method(String s)
        {
            return 5;
        }


    }


    public T METHOD(T t){
        System.out.println("Returning a "+t.getClass());
            return t;

    }



    public static void main(String[] args)
    {
        System.out.println(new MerGenerics<Number>().METHOD(3).getClass());
        System.out.println(new MerGenerics<Object>().METHOD(5).getClass());

        System.out.println(new MerGenerics<Number>().new MerGenericsJr<MilkShake>().METHOD(5).getClass());
        System.out.println(new MerGenerics<Throwable>().new MerGenericsJr<MilkShake>().STMETHOD(new Exception("whatever.")).getClass());

    }

    /*OUTPUT:
        Returning a class java.lang.Integer
        class java.lang.Integer
        Returning a class java.lang.Integer
        class java.lang.Integer
        Returning a class java.lang.Integer
        class java.lang.Integer
        class java.lang.Exception
     */

}