难以将 Google Guava map 元素添加到 java 中的数组

Question

Hello i need to add several elements from the Google Multimap class to Arrays in order to be able to pass them to the JAXB marshall method for marshalling.

public void marshall(Multimap<String, Product> supplierProducts) throws JAXBException {
        JAXBContext context = JAXBContext.newInstance(Product.class);
        Marshaller marshaller = context.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
        Product[] panasonic = new Product[10];
        Product[] apple = new Product[10];
        Product[] sony = new Product[10];

        for (Product product : supplierProducts.values()) {
        if (product.getSupplier().equals("Panasonic")) {

        } else if (product.getSupplier().equals("Apple")) {
            apple
        } else {
            sony
        }
        }
        marshaller.marshal(panasonic, new File("src/output/panasonic.xml"));
        marshaller.marshal(apple, new File("src/output/apple.xml"));
        marshaller.marshal(sony, new File("src/output/sony.xml"));

    }

In the map i have Product objects.The key is one of the 3 values:panasonic,sony or apple while the values is a product with several fields.I need to add to each array the products that contain only the specific key so that i can write to 3 sepparate xml files the products from each supplier. So the problem is that i do not know how to do this.It got really confusing really fast.Any help would be greatly appreciated !

Answer 1

you can use below approach to solve problem, Version-2:

public void marshallV1(Multimap<String, Product> supplierProducts) throws JAXBException {
        JAXBContext context = JAXBContext.newInstance(Product.class);
        Marshaller marshaller = context.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
        List<Product> panasonic = new ArrayList<>();
        List<Product> apple = new ArrayList<>();
        List<Product> sony = new ArrayList<>();

        for (Product product : supplierProducts.values()) {
        if (product.getSupplier().equals("Panasonic")) {
           panasonic.add(product ); 
        } else if (product.getSupplier().equals("Apple")) {
            apple.add(product ); 
        } else {
            sony.add(product ); 
        }
        }
        marshaller.marshal(panasonic, new File("src/output/panasonic.xml"));
        marshaller.marshal(apple, new File("src/output/apple.xml"));
        marshaller.marshal(sony, new File("src/output/sony.xml"));

    } 

Version-2:

public void marshallV2(Multimap<String, List<Product>> supplierProducts) throws JAXBException {
            JAXBContext context = JAXBContext.newInstance(Product.class);
            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
            List<Product> panasonic = supplierProducts.get("panasonic ");
            List<Product> apple = supplierProducts.get("apple ");
            List<Product> sony = supplierProducts.get("sony ");
    
  
            marshaller.marshal(panasonic, new File("src/output/panasonic.xml"));
            marshaller.marshal(apple, new File("src/output/apple.xml"));
            marshaller.marshal(sony, new File("src/output/sony.xml"));
    
        }