Java 在 HashMap 中存储特定的类类型

Question

I'm trying to implement a command line interface where you can search for products on a marketplace.

In order to allow for multiple marketplaces, I implemented a Marketplace interface. I plan on having a hash map that maps a marketplace's name (ex. Amazon) to a class the implements the Marketplace interface.

public interface Marketplace {

    static ArrayList<Product> searchForProduct(String productName) {
        throw new IllegalStateException("searchForProduct hasn't been defined");
    };

    static ArrayList<Listing> getListings(Product product) {
        throw new IllegalStateException("getListings hasn't been defined");
    }
}

How would I go about storing a class the implements the marketplace class inside a hash map as a value, and later getting that class from the hash map and call one of the static methods?

Answer 1

I think you want something like this:

Map<String, Class<? extends Marketplace>> descriptionsToClasses = new HashMap<>();

descriptionsToClasses.put("Amazon Marketplace", Amazon.class);

And finally, to invoke static methods:

Class<? extends Marketplace> marketplaceClass = descriptionsToClasses.get("Amazon Marketplace");
Method staticSearchMethod = marketplaceClass.getMethod("searchForProduct", String.class);
staticSearchMethod.invoke(null, "foo");

Make sure that the static method you are invoking is visible in the scope.