package com.test.pet;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

public abstract class PetCreator {

    private static Random random = new Random(47);
    public abstract List<Class<? extends Pet>> types();

    public Pet[] createArray(int size) {
        Pet[] pets = new Pet[size];
        for (int i = 0; i < pets.length; i++) {
            try {
                pets[i] = randomPet().newInstance();
            } catch (InstantiationException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
        return pets;
    }

    private Class<? extends Pet> randomPet() {
        int n = random.nextInt(types().size());
        return types().get(n);
    }

    public ArrayList<Pet> arrayList(int size) {
        ArrayList<Pet> result = new ArrayList<>();
        Collections.addAll(result, createArray(size));
        return result;
    }

}
 

package com.test.pet;

import java.util.ArrayList;
import java.util.List;

public class ForNameCreator extends PetCreator {

    private static List<Class<? extends Pet>> list = new ArrayList<>();
    private static String[] typeNames = {
            "com.test.pet.Mutt",
            "com.test.pet.Pug",
            "com.test.pet.EgyptianMau",
            "com.test.pet.Manx",
            "com.test.pet.Cymric",
            "com.test.pet.Rat",
            "com.test.pet.Mouse",
            "com.test.pet.Hamster"
    };

    public static void load() {
        for (int i = 0; i < typeNames.length; i++) {
            try {
                Class<? extends Pet> cls = (Class<? extends Pet>) Class.forName(typeNames[i]);
                list.add(cls);
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
    }

    static {
        load();
    }

    @Override
    public List<Class<? extends Pet>> types() {
        return list;
    }


}
 

package com.test.pet;

import java.util.HashMap;
import java.util.List;

public class PetCounter extends HashMap<String, Integer> {

    private void count(String type) {
        Integer count = get(type);
        if (count == null)
            put(type, 1);
        else
            put(type, ++count);
    }

    private static void counter(PetCreator petCreator) {
        PetCounter petCounter = new PetCounter();
        for (Pet pet : petCreator.createArray(10)){
            System.out.print(pet.getClass().getSimpleName() + " ");
            if (pet instanceof Pet)
                petCounter.count("Pet");
            if (pet instanceof Dog)
                petCounter.count("Dog");
            if (pet instanceof Mutt)
                petCounter.count("Mutt");
            if (pet instanceof Pug)
                petCounter.count("Pug");
            if (pet instanceof Cat)
                petCounter.count("Cat");
            if (pet instanceof Manx)
                petCounter.count("Manx");
            if (pet instanceof Cymric)
                petCounter.count("Cymric");
            if (pet instanceof Rodent)
                petCounter.count("Rodent");
            if (pet instanceof Rat)
                petCounter.count("Rat");
            if (pet instanceof Mouse)
                petCounter.count("Mouse");
            if (pet instanceof Hamster)
                petCounter.count("Hamster");
        }
        System.out.println();
        System.out.println(petCounter);
    }

    public static void main(String[] args) {
        counter(new ForNameCreator());
    }
}