gistfile1.java

    public Contact createContact(){
        Model.Builder<Contact> contactBuilder = new Model.Builder<Contact>()
                .setFieldValue(Contact.Field.FirstName, "first name")
                .setCustomFieldValue("FavoriteDessert", "lemon cake")
                .setFieldValue(Contact.Field.LastName, "last name");

        return contactBuilder.build();
    }

    public void addContact(YailClient client, Contact contact) throws InfusionsoftXmlRpcException, InfusionsoftParameterValidationException {
        ContactServiceAddOperation addContact = new ContactServiceAddOperation(contact);

        client.call(addContact);
    }

    public void updateContact(YailClient client, Contact contact) throws InfusionsoftXmlRpcException, InfusionsoftParameterValidationException {
        final Integer id = contact.getFieldValue(Contact.Field.Id);
        DataServiceUpdateOperation updateContact = new DataServiceUpdateOperation(id, contact);

        client.call(updateContact);
    }