類型安全很重要

package test;

import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

public class Test implements Favorite {
    private Map<Class<?>, Object> favorites = new HashMap<>();

    @Override
    public <T> void putFavorite(Class<T> type, T instance) {
        favorites.put(Objects.requireNonNull(type), type.cast(instance));
    }

    @Override
    public <T> T getFavorite(Class<T> type) {
        return type.cast(favorites.get(type));
    }

    public static void main(String[] args) {
        Test test = new Test();
        test.putFavorite(String.class, "java");
        test.putFavorite(Integer.class, 1111);

        String favorite = test.getFavorite(String.class);
    }
}