gistfile1.java

public static List<Category> getList() {
		Gson gson = new Gson();		
		
		String json_string = API.getJSON("http://u8r.herokuapp.com/categories.json");
		return Arrays.asList(gson.fromJson(json_string, Category[].class));
	}
	
	public static List<Category> getSubList(Integer category_id) {
		Gson gson = new Gson();		
		
		String json_string = API.getJSON("http://u8r.herokuapp.com/categories.json?category_id = "+category_id.toString());
		List<Category> sub_categories = Arrays.asList(gson.fromJson(json_string, Category[].class));
		
		for (Category sub_category : sub_categories) {
			String product_json_string = API.getJSON("http://u8r.herokuapp.com/products.json?category_id = "+sub_category.getId().toString());
			List<Product> products = Arrays.asList(gson.fromJson(product_json_string, Product[].class));
			
			sub_category.setProducts(products);
		}
		
		return sub_categories;
	}